explanation blue bibcodes open ADS page with paths to full text
Author name code: verma
ADS astronomy entries on 2022-09-14
author:"Verma, Virendar Kumar"
---------------------------------------------------------
Title: Lithological Mapping of Nidar Ophiolite Complex, Ladakh Using
High-Resolution Data
Authors: Chauhan, M.; Sur, K.; Chauhan, P.; Joshi, H.; Sharma, R. U.;
Chattoraj, S. L.; Verma, V. K.
2022LPICo2678.1901C Altcode:
We have utilized data from various sensors for lithological mapping
and spectral characterization of ultramafic/mafic outcrops of Nidar
ophiolite complex.
---------------------------------------------------------
Title: New Rover CONOPS with High-performance Onboard Computing:
Give Up Raw Data to Reduce Ops Cost and Do More Science
Authors: Ono, M.; Balaram, B. J.; Verma, V.; Atha, D. J.; Swan, R. M.;
Didier, A. K.
2022LPICo2655.5053O Altcode:
Imagine every scientist/engineer can uplink and run analysis scripts
on a rover like Jupyter Notebook. No need to downlink all the raw data
anymore. This will remove the comm volume constraint, simplifying and
saving the cost of tactical ops.
---------------------------------------------------------
Title: Operations for Autonomous Spacecraft: Workflows and Tools
for a Neptune Tour Case Study
Authors: Castano, R.; Vaquero, T.; Rossi, F.; Verma, V.; Choukroun,
M.; Allard, D.; Amini, R.; Barrett, A.; Castillo-Rogez, J.; Dhamani,
N.; Francis, R.; Hofstadter, M.; Ingham, M.; Jasour, A.; Jorritsma,
M.; Van Wyk, E.; Chien, S.
2022LPICo2678.2510C Altcode:
We study the problem of operations of autonomous spacecraft, identifing
workflows and tools that are well-suited for this problem.
---------------------------------------------------------
Title: Science Goals and Mission Architecture of the Europa Lander
Mission Concept
Authors: Hand, K. P.; Phillips, C. B.; Murray, A.; Garvin, J. B.;
Maize, E. H.; Gibbs, R. G.; Reeves, G.; Martin, A. M. San; Tan-Wang,
G. H.; Krajewski, J.; Hurst, K.; Crum, R.; Kennedy, B. A.; McElrath,
T. P.; Gallon, J. C.; Sabahi, D.; Thurman, S. W.; Goldstein, B.;
Estabrook, P.; Lee, S. W.; Dooley, J. A.; Brinckerhoff, W. B.; Edgett,
K. S.; German, C. R.; Hoehler, T. M.; Hörst, S. M.; Lunine, J. I.;
Paranicas, C.; Nealson, K.; Smith, D. E.; Templeton, A. S.; Russell,
M. J.; Schmidt, B.; Christner, B.; Ehlmann, B.; Hayes, A.; Rhoden,
A.; Willis, P.; Yingst, R. A.; Craft, K.; Cameron, M. E.; Nordheim,
T.; Pitesky, J.; Scully, J.; Hofgartner, J.; Sell, S. W.; Barltrop,
K. J.; Izraelevitz, J.; Brandon, E. J.; Seong, J.; Jones, J. -P.;
Pasalic, J.; Billings, K. J.; Ruiz, J. P.; Bugga, R. V.; Graham, D.;
Arenas, L. A.; Takeyama, D.; Drummond, M.; Aghazarian, H.; Andersen,
A. J.; Andersen, K. B.; Anderson, E. W.; Babuscia, A.; Backes,
P. G.; Bailey, E. S.; Balentine, D.; Ballard, C. G.; Berisford,
D. F.; Bhandari, P.; Blackwood, K.; Bolotin, G. S.; Bovre, E. A.;
Bowkett, J.; Boykins, K. T.; Bramble, M. S.; Brice, T. M.; Briggs,
P.; Brinkman, A. P.; Brooks, S. M.; Buffington, B. B.; Burns, B.;
Cable, M. L.; Campagnola, S.; Cangahuala, L. A.; Carr, G. A.; Casani,
J. R.; Chahat, N. E.; Chamberlain-Simon, B. K.; Cheng, Y.; Chien,
S. A.; Cook, B. T.; Cooper, M.; DiNicola, M.; Clement, B.; Dean, Z.;
Cullimore, E. A.; Curtis, A. G.; Croix, J. -P. de la; Pasquale, P. Di;
Dodd, E. M.; Dubord, L. A.; Edlund, J. A.; Ellyin, R.; Emanuel, B.;
Foster, J. T.; Ganino, A. J.; Garner, G. J.; Gibson, M. T.; Gildner,
M.; Glazebrook, K. J.; Greco, M. E.; Green, W. M.; Hatch, S. J.;
Hetzel, M. M.; Hoey, W. A.; Hofmann, A. E.; Ionasescu, R.; Jain, A.;
Jasper, J. D.; Johannesen, J. R.; Johnson, G. K.; Jun, I.; Katake,
A. B.; Kim-Castet, S. Y.; Kim, D. I.; Kim, W.; Klonicki, E. F.;
Kobeissi, B.; Kobie, B. D.; Kochocki, J.; Kokorowski, M.; Kosberg,
J. A.; Kriechbaum, K.; Kulkarni, T. P.; Lam, R. L.; Landau, D. F.;
Lattimore, M. A.; Laubach, S. L.; Lawler, C. R.; Lim, G.; Lin, J. Y.;
Litwin, T. E.; Lo, M. W.; Logan, C. A.; Maghasoudi, E.; Mandrake, L.;
Marchetti, Y.; Marteau, E.; Maxwell, K. A.; Namee, J. B. Mc; Mcintyre,
O.; Meacham, M.; Melko, J. P.; Mueller, J.; Muliere, D. A.; Mysore,
A.; Nash, J.; Ono, H.; Parker, J. M.; Perkins, R. C.; Petropoulos,
A. E.; Gaut, A.; Gomez, M. Y. Piette; Casillas, R. P.; Preudhomme,
M.; Pyrzak, G.; Rapinchuk, J.; Ratliff, J. M.; Ray, T. L.; Roberts,
E. T.; Roffo, K.; Roth, D. C.; Russino, J. A.; Schmidt, T. M.;
Schoppers, M. J.; Senent, J. S.; Serricchio, F.; Sheldon, D. J.;
Shiraishi, L. R.; Shirvanian, J.; Siegel, K. J.; Singh, G.; Sirota,
A. R.; Skulsky, E. D.; Stehly, J. S.; Strange, N. J.; Stevens, S. U.;
Sunada, E. T.; Tepsuporn, S. P.; Tosi, L. P. C.; Trawny, N.; Uchenik,
I.; Verma, V.; Volpe, R. A.; Wagner, C. T.; Wang, D.; Willson, R. G.;
Wolff, J. L.; Wong, A. T.; Zimmer, A. K.; Sukhatme, K. G.; Bago, K. A.;
Chen, Y.; Deardorff, A. M.; Kuch, R. S.; Lim, C.; Syvertson, M. L.;
Arakaki, G. A.; Avila, A.; DeBruin, K. J.; Frick, A.; Harris, J. R.;
Heverly, M. C.; Kawata, J. M.; Kim, S. -K.; Kipp, D. M.; Murphy, J.;
Smith, M. W.; Spaulding, M. D.; Thakker, R.; Warner, N. Z.; Yahnker,
C. R.; Young, M. E.; Magner, T.; Adams, D.; Bedini, P.; Mehr, L.;
Sheldon, C.; Vernon, S.; Bailey, V.; Briere, M.; Butler, M.; Davis,
A.; Ensor, S.; Gannon, M.; Haapala-Chalk, A.; Hartka, T.; Holdridge,
M.; Hong, A.; Hunt, J.; Iskow, J.; Kahler, F.; Murray, K.; Napolillo,
D.; Norkus, M.; Pfisterer, R.; Porter, J.; Roth, D.; Schwartz, P.;
Wolfarth, L.; Cardiff, E. H.; Davis, A.; Grob, E. W.; Adam, J. R.;
Betts, E.; Norwood, J.; Heller, M. M.; Voskuilen, T.; Sakievich, P.;
Gray, L.; Hansen, D. J.; Irick, K. W.; Hewson, J. C.; Lamb, J.; Stacy,
S. C.; Brotherton, C. M.; Tappan, A. S.; Benally, D.; Thigpen, H.;
Ortiz, E.; Sandoval, D.; Ison, A. M.; Warren, M.; Stromberg, P. G.;
Thelen, P. M.; Blasy, B.; Nandy, P.; Haddad, A. W.; Trujillo, L. B.;
Wiseley, T. H.; Bell, S. A.; Teske, N. P.; Post, C.; Torres-Castro,
L.; Grosso, C.; Wasiolek, M.
2022PSJ.....3...22H Altcode:
Europa is a premier target for advancing both planetary science
and astrobiology, as well as for opening a new window into the
burgeoning field of comparative oceanography. The potentially habitable
subsurface ocean of Europa may harbor life, and the globally young and
comparatively thin ice shell of Europa may contain biosignatures that
are readily accessible to a surface lander. Europa's icy shell also
offers the opportunity to study tectonics and geologic cycles across
a range of mechanisms and compositions. Here we detail the goals and
mission architecture of the Europa Lander mission concept, as developed
from 2015 through 2020. The science was developed by the 2016 Europa
Lander Science Definition Team (SDT), and the mission architecture was
developed by the preproject engineering team, in close collaboration
with the SDT. In 2017 and 2018, the mission concept passed its mission
concept review and delta-mission concept review, respectively. Since
that time, the preproject has been advancing the technologies, and
developing the hardware and software, needed to retire risks associated
with technology, science, cost, and schedule.
---------------------------------------------------------
Title: Study of some characteristics of solar energetic particles
and associated solar activities during 1996-2016
Authors: Mittal, Nishant; Verma, V. K.
2019NewA...69...74M Altcode:
Solar energetic particles (SEP) are believed to originate from two
different sources, coronal mass ejections (CMEs) and solar flares. In
this paper, we have also investigated some statistical properties such
as speed, apparent angular width, acceleration, latitude distribution
of SEP effective CMEs observed during the period 1996-2016 covering the
solar cycle 23 and solar cycle 24. We find that 76% SEP event associated
with solar flares originates in the western hemisphere. We also found
that SEP associated CMEs are faster and nearly halo in nature. The
study shows that mean starting frequency of SEP events associated
DH-type II radio burst is 10.9 MHz. We have also investigated the time
delay between the flare start/peak time and related SEP, CME and type
II burst start time and it is to be found that almost all SEP events
occur later than the start time of the flare, CME, m-type II bursts
and DH type II radio events.
---------------------------------------------------------
Title: On the Origin of Solar Halo Coronal Mass Ejections
Authors: Verma, V. K.; Mittal, Nishant
2019AstL...45..164V Altcode:
We present an investigation of halo coronal mass ejections (HCMEs) to
understand the origin of HCMEs which is very important because HCMEs are
regarded as main causes of heliospheric and geomagnetic disturbances. In
this study, we have investigated 313 HCMEs observed during 1996-2012 by
LASCO, coronal holes (CHs) and solar flares phenomena. On investigation
of 313 HCMEs and related solar flares and coronal holes data, we find
that all 313 HCMEs were observed when there were CHs and solar flares
within 10° to 60°. We also find that the 128 (40.8%) and 74 (23.6%)
HCMEs events were observed when there were CHs and solar flares within
10° and 20°, respectively. The speed of HCMEs does not increase with
the increase of the area of CHs while the solar winds speed increases
with increase of CHs area. We are of the view that the HCMEs may have
been produced by some mechanism, in which the mass ejected by solar
flares or active prominences, gets connected with the open magnetic
lines of CHs (source of high speed solar wind streams) and moves
along them to appear as a HCMEs, earlier suggested by Verma and Pande
(1989) and Verma (1998, 2002). The various results obtained in the
present analysis are discussed in the light of existing scenario of
heliospheric physics.
---------------------------------------------------------
Title: On some characteristics of large kinetic energy coronal mass
ejections during 1996-2015
Authors: Mittal, Nishant; Verma, V. K.
2018NewA...63....6M Altcode:
We have studied the characteristics of large kinetic energy coronal mass
ejections (LE-CMEs) (kinetic energy ≥1E + 31 ergs) observed between
the time period years 1996-2015. During the study period, total 1250
CMEs occurred, which have their kinetic energy ≥1E + 31 ergs. Out
of these 1250 events; only 314 events have proper acceleration,
mass, kinetic energy and velocity, so other events are left out due
to uncertainty or non availability of data. Out of 314 LE-CMEs there
are 207 LE-CMEs those are not associated with solar flare events. Only
107 LE-CME events are associated with flares on solar disc. Our study
shows that the average and the median linear speed of 314 LE-CMEs events
are 835 km/s and 817 km/s, respectively. There are 197 LE-CMEs those
are halo but we left out them from our study because of uncertainty in
mass and energy. The angular widths of LE-CMEs for selected data set
are less than ≤120° with a mean value of angular width as 84°. The
mean value of mass and kinetic energy of LE-CMEs is 8.96E + 15 g and
2.38E + 31 ergs, respectively. The mean value of acceleration of large
kinetic energy CMEs is 0.84 m/s<SUP>2</SUP>. It is also found that most
of the events are biased towards acceleration that shows that large
kinetic energy CMEs accelerate in general. The study also shows that
107 large kinetic energy CMEs associated with flares occurred when there
is coronal holes (CH) in the nearby area and the mean distance between
CMEs/ flares and the boundary of a coronal hole (CH) is 24°. We also
find that mass and kinetic energy of CMEs do not depend on the location
of CME and associated flare on the solar disc. It is also found that
it is not necessary that energetic flares should associate with LE-CMEs.
---------------------------------------------------------
Title: Multi-wavelength view of an M2.2 solar flare on 26 november
2000
Authors: Chandra, R.; Verma, V. K.; Rani, S.; Maurya, R. A.
2017NewA...51..105C Altcode: 2016arXiv160805796C
In this paper, we present a study of an M2.2 class solar flare of
26 November 2000 from NOAA AR 9236. The flare was well observed
by various ground based observatories (ARIES, Learmonths Solar
Observatory) and space borne instruments (SOHO, HXRS, GOES) in
time interval between 02:30 UT to 04:00 UT. The flare started with
long arc-shape outer flare ribbon. Afterwards the main flare starts
with two main ribbons. Initially the outer ribbons start to expand
with an average speed (∼20 km s-<SUP>1</SUP>) and later it shows
contraction. The flare was associated with partial halo coronal mass
ejection (CMEs) which has average speed of 495 km s-<SUP>1</SUP>. The
SOHO/MDI observations show that the active region was in quadrupolar
magnetic configuration. The flux cancellation was observed before the
flare onset close to flare site. Our analysis indicate the flare was
initiated by the magnetic breakout mechanism.
---------------------------------------------------------
Title: Relationship of decametric-hectometric type II radio burst,
coronal mass ejections and solar flare observed during 1997-2014
Authors: Mittal, Nishant; Verma, V. K.
2017NewA...50...60M Altcode:
In the present study we have investigated 426 DH Type II radio burst and
associated CMEs events observed during the time period of 1997-2014. The
starting frequency of most of associated DH type-II bursts (85%) lies
in the range of 1-14 MHz (364 out of 426) with mean value of starting
frequency is ∼11 MHz. The study of starting frequency (1-16 MHz) of
DH type II bursts and heliocentric distance in solar radii indicate
that DH type II radio bursts originate from 2.2-4.5 (R<SUB>S</SUB>)
heliocentric distance in solar radii. We also found that the ∼ 48%
DH Type II radio bursts associated CMEs are located between ± 40°
of solar central disc and we also found that duration of DH type II
radio bursts located at solar disc center are more than the duration
of DH type II radio bursts located at solar limb. It is found that
mean value for linear and initial speed of DH Type II associated
CMEs are 1157 km/s and 1200 km/s, respectively. The CMEs speed are
not correlated with duration of DH Type II radio bursts indicate that
the durations of DH Type II radio bursts does not depend on speed of
CMEs. The study also show that 426 DH type II radio bursts associated
CMEs/flares occurred when there is coronal holes(CH) in nearby area
and the mean distance between DH type II burst associated CMEs/
flares and boundary of coronal hole (CH) is 26°. The study also
shows that there is no relation between drift velocity of DH type II
radio bursts and speed of CMEs. The study also indicate that about 45%
flares those associated DH Type II radio bursts have duration about 60
minutes and long duration DH Type II radio bursts are associated with
X-class flares. We have also discussed that the results obtained in the
present investigation in view of latest heliophysics interpretations.
---------------------------------------------------------
Title: Relationship of EIT waves phenomena with Coronal Mass Ejections
Authors: Verma, V. K.
2017psio.confE..68V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the statistical characteristics of radio-loud and
radio-quiet halo coronal mass ejections and their associated flares
during solar cycles 23 and 24
Authors: Mittal, Nishant; Sharma, Joginder; Verma, Virendar Kumar;
Garg, Vijay
2016NewA...47...64M Altcode:
We have studied the characteristics of radio-loud (RL) and
radio-quiet (RQ) front side halo coronal mass ejections (HCMEs)
(angular width 360<SUP>°</SUP>) observed between the time period
years 1996-2014. RL-HCMEs are associated with type II radio bursts,
while RQ-HCMEs are not associated with type II radio bursts. CMEs near
the Sun in the interplanetary medium associated with radio bursts
also affect the magnetosphere. The type II radio burst data was
observed by WIND/WAVES instrument and HCMEs were observed by LASCO/
SOHO instruments. In our study, we have examined the properties of
RL-HCMEs and RQ-HCMEs and found that RL-HCMEs follow the solar cycle
variation. Our study also shows that the 26% of slow speed HCMEs and 82%
of fast speed HCMEs are RL. The average speed of RL-HCMEs and RQ-HCMEs
are 1370 km/s and 727 km/s, respectively. Most of the RQ-HCMEs occur
around the solar disc center while most of RL-HCMEs are uniformly
distributed across the solar disc. The mean value of acceleration
of RL-HCMEs is more than twice that of RQ-HCMEs and mean value of
deceleration of RL- HCMEs is very small compare to RQ-HCMEs events. It
is also found that RQ-HCMEs events are associated with C- and M-class
of SXR flares, while RL-HCMEs events are associated with M and X-class
of SXR flares, which indicates that the RQ-HCMEs are less energetic
than the RL-HCMEs. We have also discussed the various results obtained
in present investigation in view of recent scenario of solar physics.
---------------------------------------------------------
Title: AEGIS Intelligent Targeting Deployed for the Curiosity Rover's
ChemCam Instrument
Authors: Francis, R.; Estlin, T.; Gaines, D.; Doran, G.; Gasnault,
O.; Johnstone, S.; Montaño, S.; Mousset, V.; Verma, V.; Bornstein,
B.; Burl, M.; Schaffer, S.; Wiens, R. C.
2016LPI....47.2487F Altcode:
Rover picks, zaps rocks / Without Earth-in-the-loop wait / More
mission science.
---------------------------------------------------------
Title: On Halo CMEs relation with Solar Flares and Coronal Holes
observed during 1996-2008
Authors: Verma, V. K.
2012cosp...39.2083V Altcode: 2012cosp.meet.2083V
In the present paper we have studied the reconnection of chromospheric
active regions events and uni-polar regions (Coronal Holes/CH)
leading to the production of solar halo coronal mass ejections
(HCMEs). To carry out this study we have used HCMEs data for the
period April 1996 and December 2008 observed by LASCO/ SOHO and the
daily solar CH maps observed and CH synoptic chart prepared at KPNO
for the same period. We also used solar activity events data recorded
by EIT instruments aboard SOHO, X-ray images of Sun recorded by
Yohkoh mission, solar activity events recorded in Hα emission from
various ground based-based observatories. To understand the role of
CH maps in 10830 A and Chromospheric solar active region events we
first matched time of onset of HCMEs with time of solar events in
Hα or EIT data. Secondly we looked for the spatial location of solar
activity phenomena and CH maps on the solar disk. From this study we
find that 29.5% HCMEs were observed when there were CHs within 1-10
degree of flares locations, 26.5% H-CMEs were observed when there
were CHs within 11-20 degree of flares locations, 17.9% HCMEs were
observed when there were CHs within 21-30 degree of flares locations,
14.5% H-CMEs were observed when there were CHs within 31-40 degree
of flares locations, and 11.6% H-CMEs were observed when there were
CHs within > 40 and ∼60 degree of flares locations. We are of the
view that the HCMEs have been produced by some mechanism, in which the
mass ejected by some solar flares or active prominences, gets connected
with the open magnetic lines of CHs (source of high speed solar wind
streams) and moves along them to appear as suggested earlier by Verma
and Pande (1989) and Verma (1998). References: Verma, V. K. &
Pande, M. C. (1989) Proc. IAU Colloq. 104 Solar and Stellar Flares
(Poster Papers), Stanford University, Stanford, USA, p.239. Verma,
V. K.(1998) Journal of Geophysical Indian Union, 2, 65.
---------------------------------------------------------
Title: On the arrival times of halo coronal mass ejections in the
vicinity of the Earth
Authors: Mittal, Nishant; Verma, V. K.
2012cosp...39.1255M Altcode: 2012cosp.meet.1255M
It is well known that the arrival times of Coronal Mass Ejections
(CMEs) in the vicinity of the Earth play an important role for solar
terrestrial environment. For the forecasting of Space Weather, It is
necessary to predict the CMEs arrival time at 1 AU. Here, using LASCO
halo CMEs data of 246 events observed during time period 1996-2008,
we have tried to predict the arrival times as accurately as possible
of full halo CMEs only. We have also studied arrival time of halo CMEs
associated with type II radio bursts and X-class soft x-ray bursts,
separately. The results obtained in the present investigation are
discussed in the light recent scenario of CMEs understanding.
---------------------------------------------------------
Title: On Multi-wavelength Study of a M2.2 Solar Flare Observed on
26 November, 2000 from NOAA AR 9236
Authors: Verma, V. K.; Chandra, Ramesh
2012cosp...39.2084V Altcode: 2012cosp.meet.2084V
No abstract at ADS
---------------------------------------------------------
Title: Relationship of great soft X-ray flares with other solar
activity phenomena
Authors: Verma, V. K.
2011Ap&SS.334...83V Altcode: 2011Ap&SS.tmp..173V
We present study of relationship of GSXR flares with H α flares,
hard X-ray (HXR) bursts, microwave (MW) bursts at 15.4 GHz, type II/IV
radio bursts, coronal mass ejections (CMEs), protons flares (>10
MeV) and ground level enhancement (GLE) events we find that about
85.7%, 93%, 97%, 69%, 60%, 11.1%, 79%, 46%, and 23%% GSXR flares are
related/associated with observed H α flares, HXR bursts, MW bursts at
15.4 GHz, type II radio bursts, type IV radio bursts, GLE events, CMEs,
halo CMEs, and proton flares (>10 MeV), respectively. In the paper
we have studied the onset time delay of GSXR flares with H α flares,
HXR, and MW bursts which shows the during majority GSXR flares SXR
emissions start before the H α, HXR and MW emissions, respectively
while during 15-20% of GSXR flares the SXR emissions start after
the onset of H α, HXT and MW emissions, respectively indicating two
types of solar flares. The, onset time interval between SXR emissions
and type II radio bursts, type IV radio bursts, GLE events CMEs, halo
CMEs, and protons flares are 1-15 min, 1-20 min, 21-30 min, 21-40 min,
21-40 min, and 1-4 hrs, respectively. Following the majority results
we are of the view that the present investigations support solar
flares models which suggest flare triggering first in the corona and
then move to chromospheres/ photosphere to starts emissions in other
wavelengths. The result of the present work is largely consistent with
"big flare syndrome" proposed by Kahler (1982).
---------------------------------------------------------
Title: Mars Exploration Rover Opportunity Terramechanics Across
Ripple Covered Bedrock in Meridiani Planum
Authors: Arvidson, R. E.; van Dyke, L.; Bennett, K.; Zhou, F.;
Iagnemma, K.; Senatore, C.; Lindemann, R.; Trease, B.; Maxwell, S.;
Bellutta, P.; Stroupe, A.; Hartman, F.; Verma, V.; Ali, K.
2011LPI....42.1503A Altcode:
This abstract summarizes Opportunity's drives since leaving Victoria
crater, issues associated with high slippage and sinkage during
traverses, and soil and terrain properties retrieved from modeling
the drives and the wheel-soil interactions.
---------------------------------------------------------
Title: On the Long-Term Cyclic Period of North-South Asymmetry of
Solar Active Region Phenomena
Authors: Verma, V. K.
2009ASPC..416..483V Altcode:
In this paper we have studied North-South (N-S) asymmetry of various
solar phenomena for the period of solar cycles 6-23. The data includes
sunspot data, flares (x-ray, white light, etc.) data and active
prominences. The present study shows that the N-S asymmetry has a
long-term period of 11 solar cycles.The study also shows that the
N-S asymmetry during solar cycles 22 and 23 are southern dominated as
predicted by Verma (1992). On the basis of this study we are of the
view that N-S asymmetry for various solar phenomena may be southern
dominated during solar cycle 24 and that the asymmetry may shift to
the northern hemisphere during solar cycle 25 as suggested by Verma
(1992). The result of this study may be helpful to understand long-term
helioseismic phenomena and dynamo models of the Sun which are based
on the magnetic fields related to solar active regions.
---------------------------------------------------------
Title: Plan Execution Interchange Language (PLEXIL) for Executable
Plan and Command Sequence
Authors: Verma, V.; Estlin, T.; Jonsson, A.; Pasareanu, C.; Simmons,
R.; Tso, K.
2005ESASP.603E..11V Altcode: 2005aira.confE..11V
No abstract at ADS
---------------------------------------------------------
Title: Classification of Solar Coronal Mass Ejections Based on
LASCO Observations
Authors: Verma, V. K.; Sawant, H. S.
2004cosp...35..629V Altcode: 2004cosp.meet..629V
In this paper we present a new classification of solar coronal mass
ejections (CME) based on initail speed of CMEs events observed by
LASCO/ SOHO. As we know that for mass ejections from Sun's surface
the required escape velocity is about 618 km/sec and as the height
increases in the solar atmosphere the escape velocity of mass ejection
decreases with height of solar atmosphere. Keeping this fact in mind,
we have studied and classified the CMEs observed in years 2000, 2001,
2002 and 2003. In classifying CMEs we assume that if the initial
observed speed of CMEs material is less than the escape velocity at
that solar atmospheric height then we call such CMEs as non-escape
speed-CMEs(NES-CMEs) and if the initial speed of CMEs material is more
than the escape velocity at that solar atmospheric height then we call
such CMEs as escape speed-CMEs(ES-CMEs). Further, if the initial speed
of CMEs material is more 1000 km/sec at that solar atmospheric height
then we call such CMEs as high speed-CMEs(HS-CMEs). From the study
of LASCO CMEs observed in years 2000, 2001, 2002 and 2003 we found
that about 42% CMEs were NES-CMEs, 48% CMEs were ES-CMEs and ∼ 10%
CMEs were HS-CMEs. We further studied the few properties of NES-CMES,
ES-CMEs and HV-CMEs that includes latitudinal distribution, speed
distribution, accelaration distribution and duration distribution
etc. of all classes of CMEs.
---------------------------------------------------------
Title: Relatioship of Coronal Mass Ejections observed by LASCO/
SOHO with Solar flares and Coronal Holes
Authors: Verma, V. K.; Sawant, H. S.
2004cosp...35..628V Altcode: 2004cosp.meet..628V
The CMEs observed by LASCO coronagraph and associated solar activity
phenomena whose locations were identified by EIT instruments and
solar H-alpha flares observations during years 2000, 2001, 2002 and
2003 indicate that about 40%, 26% and 30% CMEs were observed when
there were coronal holes (CHs) within 1-10, 11-20 and 21-40 degrees,
respectively from the location of solar H-alpha flares. The CHs data
used in the study were taken from KPNO, USA website. From the study
carried out in the present paper we are of the view that CMEs might
have been produced by some mechanism by which the mass ejected by some
solar flares or active prominences, gets connected with open magnetic
lines of CHs (source of high speed solar wind streams) and moves along
them to appear as CMEs.
---------------------------------------------------------
Title: Solar Flares Activity in Active Region NOAA 9033 on 12th
June 2000
Authors: Verma, V. K.; Sawant, H. S.
2004cosp...35..630V Altcode: 2004cosp.meet..630V
In the paper, we present a study of three homologous H-alpha flares
observed on 12th June 2000 in active region (AR) NOAA 9033. During the
observation of AR NOAA 9033 on 12th June 2000, we observed 1st solar
flare between 0135-0155 UT, 2nd flare between 0236-0253 UT and 3rd flare
between 0259-0323 UT. We have also analysed 17 GHz radio data observed
from Nobeyama Observatory, Japan of same location and same duration to
understand the origin of flare like activity in H-alpha and 17 GHz radio
data. The present study support the quadrapolar reconnection scenario
and also shows the presence of 6.7 min periodcity in intensity data
estimated from the site of the homologous flares.
---------------------------------------------------------
Title: Study of Three Homologous Solar Flares Observed from Active
Region NOAA 9033 on 12th June 2000
Authors: Verma, V. K.; Vats, Hari Om
2003BASI...31..289V Altcode:
In the paper, we present a study of three homologous H flares
observed on 12th June 2000 in active region (AR) NOAA 9033. During
the observation of AR NOAA 9033 on 12th June 2000, we observed 1st
solar flare between 0135-0155 UT, 2nd flare between 0236-0253 UT
and 3rd flare between 0259-0323 UT. The present study supports the
quadrapolar reconnection scenario presented by Machado et al. (1983)
and also shows the presence of 26.7 min periodicity in intensity data
estimated from the site of the homologous flares.
---------------------------------------------------------
Title: Estimation of Fried's Parameter From Specklegrams of Solar
Features
Authors: Sridharan, R.; Venkatakrishnan, P.; Verma, V. K.
2002SoPh..211..395S Altcode:
A few methods of estimating Fried's parameter (r<SUB>0</SUB>) from
specklegrams of solar features are described. Some of these methods
were used to estimate r<SUB>0</SUB> for the speckle data obtained from
Kodaikanal Observatory (KO), Uttar Pradesh State Observatory (UPSO)
and Udaipur Solar Observatory (USO). The average value of r<SUB>0</SUB>
was found to be ∼ 3 cm at USO and UPSO during our observations. At
KO, values of r<SUB>0</SUB> ranging from 6 to 10 cm were estimated.
---------------------------------------------------------
Title: On the occurrence rate of slow speed solar wind strams
Authors: Verma, V.
2002cosp...34E1915V Altcode: 2002cosp.meetE1915V
We have investigated the rate of occurrence of slow speed solar wind
(SSSW) streams observed between 1977-1983 using power spectrum analysis
technique. The data for this analysis have been taken from the paper by
Lundstedt (1989). The power spectrum analysis of SSSW streams indicate
that SSSW stream events have a periodicity of 6.0 and 3.0 days. The 3.0
days is a folding frequency of 6.0 days. Since according to Lundstedt
(1989) the SSSW events originate from the regions above the coronal
neutral line therefore 6.0 days periodicity may be the time for energy
build up period in regions above the coronal neutral line to produce
a SSSW events. References: Lundstedt, H. (1989) Solar Physics, 123, 177.
---------------------------------------------------------
Title: Coronal Mass Ejections: Relationship with Solar Flares and
Coronal Holes
Authors: Verma, V. K.
2002mwoc.conf..319V Altcode:
The results of an analysis of the relationship of coronal mass ejections
(CMEs) with solar flares and coronal holes are presented. In the
present study CME's observed by LASCO coronagraph and whose locations
were identified by EIT instruments are used in the present study. The
coronal holes data used in study were observed by KPNO, USA. From the
study we have found that about 40% CMEs were observed when there were
coronal holes within 5 degrees from the location of solar flares and
22% CMEs were observed when there were coronal holes within 10 degrees
from the location of solar flares. Further, 33% CMEs were observed
when there were coronal holes present within 15-25 degrees from the
location of solar flares. The present work supports the view that the
origin of CME's has a relationship with coronal holes in close vicinity
as suggested by Verma and Pande(1989) and Verma(1998).
---------------------------------------------------------
Title: Study of periodicities of high speed solar wind streams
observed during solar cycles 20, 21 and 22.
Authors: Verma, V.
2002cosp...34E1854V Altcode: 2002cosp.meetE1854V
Here we have investigated the periodicity of high speed solar wind
(HSSW) streams using the technique of power spectrum analysis. The
data for HSSW streams has been taken from the papers by Lindblad and
Lundstedt (1981), Mavromichalaki et.al.(1988),and Mavromichalaki and
Vassilaki (1998). The power spectrum analysis of the daily HSSW streams
events for the period 1965-76(solar cycle 20) shows peaks of 14, 7,
2.9 and 2.4 days, daily HSSW events for the period 1977-86 (solar cycle
21) shows peaks of 7.0,5.2, 3.4, and 2.9. and daily HSSW events for
the period 1987-96(solar cycle 22) shows peaks of 7.4, and 2.8. The
HSSW events for period 1965-96(solar cycles 20,21 and 22) shows peaks
of 7, 2.9 and 2.6 days. The common period from above study is 7 and
2.9 days. The 2.9 days and others period are folding frequency. The 7
days periodicity is close to the 1/4th of solar rotation which may
be the time for energy build for coronal holes to produce a HSSW
streams. References: Lindblad, B. A., and Lundstedt, H.(1981)Solar
Phys., 74,197. Mavromichalaki, H., et.al.(1988) Solar Phys.,115,
345. Mavromichalaki, H and Vassilaki, A (1998) Solar Phys.,183, 181.
---------------------------------------------------------
Title: Periodic behaviour of the North-South Asymmetry of Solar
Phenomena
Authors: Verma, V.
2002cosp...34E1852V Altcode: 2002cosp.meetE1852V
We report here a study of various solar phenomena occurring in both
north and south hemispheres of the Sun during solar cycles 8-23. In the
study we have used sunspot data for the period 1832-1976 and 01/1996
to 04/2002 and flare index data for the period 1936-1993 (Atac and
Ozguc, 1996), Hα flare data 1993-1998 and solar active prominences
data for the period 1957-1998. Earlier Verma (1992,1993) reported
long-term cyclic period in N S asymmetry and also reported that the
N-S- asymmetry of solar activity phenomena during solar cycles 21, 22,
23 and 24 will be south dominated and the N-S asymmetry will shift to
north hemisphere in solar cycle 25. The present study shows that the
N-S asymmetry during solar cycles 22 and 23 are southern dominated
as suggested by Verma (1992). References: Atac, T. and Ozguc, A.,
1996,Solar Phys., 166, 201 Verma, V. K., 1992, ASP Conf. Series, 27,
429. Verma, V. K., 1993, Ap. J., 403, 797.
---------------------------------------------------------
Title: Relatioship of Coronal Mass Ejections with Solar flares and
Coranal Holes
Authors: Verma, V.
2002cosp...34E1853V Altcode: 2002cosp.meetE1853V
The CMEs observed by LASCO coronagraph and associated solar activity
phenomena whose locations were identified by EIT instruments and solar
Hα flares observations during years 2000 and 2001 indicate that about
40%, 26% and 30% CMEs were observed when there were coronal holes (CHs)
within 1-10, 11-20 and 21-40 degrees, respectively from the location
of solar Hα flares. The CHs data used in the study were taken from
KPNO, USA website. From the study carried out in the present paper we
are of the view, as also earlier sugge sted by Verma and Pande (1989),
that CMEs might have been produced by some mechanism by which the mass
ejected by some solar flares or active prominences, gets connected with
open magnetic lines of CHs (source of high speed solar wind streams)
and moves along them to appear as CMEs. References: Verma, V. K. &
Pande, M. C, Proc. IAU Colloq. 104 " Solar and Stellar Flares" Poster
Paper (Eds. B. M. Haisch and M. Rodono), Stanford University, Stanford,
USA, p. 239 (1989)
---------------------------------------------------------
Title: On the Periodicity of High Speed Solar Wind Streams
Authors: Verma, V. K.
2001SSRv...97..205V Altcode:
In the paper we have investigated the periodicity of high speed solar
wind (HSSW) streams using the technique of power spectrum analysis. The
data for HSSW streams has been taken from the papers by Lindblad and
Lundstedt (1981, 1983) and Lindblad et al. (1989) The power spectrum
analysis of the daily HSSW streams events for the period 1964 1975
(solar cycle 20) shows peaks of 14, 7, 2.9 and 2.6 days, and daily HSSW
events for the period 1976 1982 (solar cycle 21) shows peaks of 15.4,
7, 2.9 and 2.6 days. The HSSW events for period 1964 1982 (solar cycles
20-21) shows peaks of 15.4, 7, 3.7, 2.9 and 2.6 days. The common periods
from above study are 7, 2.9 and 2.6 days. The 2.9, 2.6 days and other
periods are folding frequency. The 7 days periodicity is close to the
1/4th of solar rotation which may be the time for energy build up for
coronal holes to produce HSSW streams.
---------------------------------------------------------
Title: Periodic Variation of the North-South Asymmetry of Solar
Activity Phenomena
Authors: Verma, V. K.
2000JApA...21..173V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the distribution and asymmetry of solar active prominences
Authors: Verma, V. K.
2000SoPh..194...87V Altcode:
The paper presents the results of a study of the distribution and
asymmetry of solar active prominences (SAP) for the period 1957-1998
(solar cycles 19-23). The east-west (E-W) distribution study shows that
the frequency of SAP events in the 81-90° slice (in longitude) near
the east and west limbs is up to 10 times greater than in the 1-10°
slice near the central meridian of the Sun. The north-south (N-S)
latitudinal distribution shows that the SAP events are most prolific
in the 11-20° slice in the northern and southern hemispheres. Further,
the E-W asymmetry of SAP events is not significant. The N-S asymmetry of
SAP events is significant and it has no relation with the solar maximum
year or solar minimum year during solar cycles. Further, the present
study also shows that the N-S asymmetry for cycles 19-23 follows and
confirms the trend of N-S asymmetry cycles as reported by Verma (1992).
---------------------------------------------------------
Title: Surge activities on November 26-28, 1990
Authors: Uddin, Wahab; Verma, V. K.
2000BASI...28..125U Altcode:
We report here a study of 8 solar surges observed in H? emission on the
west solar limb (active region NOAA 6368) on 26, 27 and 28 November
1990. Three surges were observed on 26 November of durations 35, 86
and 40 min at the time intervals of 20 and 25 min respectively for
successive events. Again in the same active region, we have observed
two solar surges of durations 56 and 101 min on 27 November at an
interval of 10 min. Three surges were also observed on 28 November of
durations 25, 138 and 95 mins at the time intervals of 10 and 20 min
respectively for successive events. Using photographic observations, we
have studied the morphological behaviour and estimated the height, mass,
radial velocity, mechanical energies and magnetic fields associated
with the 8 surges. The x-ray and radio data observed during the surges
are also included in the study. The various parameters estimated from
the observed data are discussed in light of solar surge theories.
---------------------------------------------------------
Title: Development of an Instrument for the Observation of Solar
Hα Flares With Time Resolution of 25 ms
Authors: Verma, V.
1999ASPC..183..288V Altcode: 1999hrsp.conf..288V
No abstract at ADS
---------------------------------------------------------
Title: Proposed 60-cm Solar Vacuum Telescope with Multi-Channel
Facility of UPSO, Nainital, India
Authors: Verma, V.
1999ASPC..183..213V Altcode: 1999hrsp.conf..213V
No abstract at ADS
---------------------------------------------------------
Title: Eruption of Twisted Filament and Associated Phenomena
Authors: Uddin, W.; Verma, V. K.
1998ASPC..150..338U Altcode: 1998IAUCo.167..338U; 1998npsp.conf..338U
No abstract at ADS
---------------------------------------------------------
Title: Eruption of twisted filament, associated flare and transient
phenomena
Authors: Uddin, Wahab; Verma, V. K.
1998BASI...26..200U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar observational programs and facilities at UPSO, Naini Tal
Authors: Gaur, V. P.; Verma, V. K.; Uddin, W.
1998BASI...26..289G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Proposed 60-cm multichannel Solar Vacuum Telescope of UPSO,
Naini Tal
Authors: Verma, V. K.; Uddin, W.; Gaur, V. P.
1998BASI...26..411V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Development of an Instrument Based on a Fibre-Bonded CCD
Camera for Prominence Observations
Authors: Verma, V. K.; Uddin, W.; Gaur, V. P.
1998ASPC..150..506V Altcode: 1998IAUCo.167..506V; 1998npsp.conf..506V
No abstract at ADS
---------------------------------------------------------
Title: Development of H alpha Prominence Monitoring System Based on
the Fibre-Bonded CCD Camera
Authors: Verma, V. K.; Uddin, Wahab; Gaur, V. P.
1997IAUJD..19E..53V Altcode:
Solar prominences are faint coronal features that are well observed
through H alpha filters of passband 2 to 3 AA . The formation and
disappearance of solar prominence are not well understood because
of lack homogeneously observed data. In an attempt to improve the
situation, we have developed and tested an instrument based on
fibre-bonded CCD camera for the prominence observations. To record
faint prominence features, we are using solid aluminized glass cone
which reflect the bright photospheric light outside the telescope
tube. The CCD camera system employ thermo-electrically cooled FTS
cooled probe camera head (ambient temperature -42 C) with TK 1024
CCD class I chip (pixel size 24 times 24 micron). A fibre-bonded CCD
instrument is installed at the focus of 15 cm f/15 coude's refractor
telescope after H alpha filter. The Poster provides further details
on the system. The instrument provides data for studies of the origin
of coronal mass ejections. Solar prominences observed in H alpha with
the new prominence monitor is used to study the relationship between
solar prominences and coronal mass ejection events as observed with
SOHO coronagraph.
---------------------------------------------------------
Title: Development of H alpha Flare Observing System Based on the
CCD Camera Time Resolutions of 25 MS
Authors: Verma, V. K.; Uddin, Wahab; Gaur, V. P.
1997IAUJD..19E..54V Altcode:
The H alpha emission line (6563 AA) provide spatial information
very accurately to study electron time of flight information which
is crucial for determining the energy release processes in solar
flare. Kampher and Magun (1983) and other have shown that there is
a component of the H alpha emission that shows impulsive variations
that coincide with microwave spikes. The expected rapid onset of H
alpha during flares will be compared with microwave and hard X-ray
emission to understand the physical processes in solar flares during
flare triggering. Keeping the above problem in mind we have developed
and tested a CCD camera (100x100 pixels) system for observing H alpha
images of the solar flares with time resolution > 25 ms. This CCD
camera system employ CCD chip EEV37 (512x512 pixels), pixel sizes 15
micron The camera controller of the system has variable read out rate
0.5 - 4.0 Mega pixels/s with 12 bit (4096 grey levels) resolution. At
present the CCD system has maximum read out rate of 2M pixels/s. The
Poster gives further details about the system. A flare time profile and
contours of solar H alpha flare kernel, will be presented and discussed
and serve to demonstrate the performance of the new instrument.
---------------------------------------------------------
Title: CCD observations of the total solar eclipse of October 24,
1995.
Authors: Verma, V. K.; Uddin, W.; Gaur, V. P.; Joshi, G. C.; Bondal,
K. R.
1997KodOB..13...29V Altcode:
The observations of the solar corona during this solar eclipse
were attempted in white light and in narrow band filters with peak
wavelengths centered at 5303 Å (Fe XIV) and at 6474 Å [Fe X],
the coronal emission lines. The equipment used for the observations
is briefly discussed. Nine coronal images in the red line were
successfully obtained. The preliminary results of the observations
are also presented.
---------------------------------------------------------
Title: Total solar eclipse observations of 24 October 1995 from Meja
Khas, Allahabad
Authors: Verma, V. K.; Uddin, Wahab; Gaur, V. P.; Joshi, G. C.;
Bondal, K. R.; Pant, P.
1996BASI...24..653V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Development of a High Speed CCD Camera System for the
Observation of Solar Hα Flares
Authors: Verma, V. K.; Uddin, Wahab; Gaur, V. P.
1996JKASS..29..391V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Eruptive prominence associated with limb flare of 25 January
1991
Authors: Uddin, Wahab; Verma, V. K.
1996Ap&SS.243..173U Altcode: 1996IAUCo.154..173V; 1996Ap&SS.243..173V
We have observed an eruptive prominence at the east solar limb on 25
January 1991 which started earlier than 0623 UT and was associated
with a limb flare (S16 E90) of class 1B/ X10.0. We have recorded
a huge mass ejection in the corona by the limb flare associated
eruptive prominence. The eruptive prominence ejected a part of the
loop in the corona with maximum speed of about 1280 km/sec. The
ejected material attain height upto 150,000 km in the corona and
finally faded/disappeared in the corona. During the ascending phase
of the prominence material in the corona there was a unscrewing of
the loop system associated with the eruptive prominence. The type
II, III, and IV radio bursts were also reported by a number of Radio
Observatories during observation of the eruptive prominence. The high
flux of sudden ionospheric disturbances and the solar radio emissions
on fixed frequencies (245 80000 MHz) were also recorded. The eruptive
prominence associated with limb flare also shows increased proton flux
(>10 MeV) during its occurence. The flare was classified as X10.0
flare. In this paper we have analysed the observed data and compared
it with the theoretical model of the solar flare.
---------------------------------------------------------
Title: Eruptive Prominence Associated with Limb Flare of 1991JAN25
Authors: Uddin, W.; Verma, V. K.
1995JApAS..16..385U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Study of Solar Flares Observed in Hard X-Ray and Soft X-Ray
Emissions
Authors: Verma, V. K.; Pande, M. C.
1995JApAS..16..385V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recurrent Surge Activity from Active Region NOAA:6368
Authors: Uddin, W.; Verma, V. K.; Pande, M. C.
1995JApAS..16..387U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Relationship of coronal mass ejections with solar flares,
prominences and coronal holes
Authors: Verma, V. K.; Uddin, Wahab
1995sowi.confR..98V Altcode:
We have investigated more than 450 coronal mass ejections (CME's)
observed between 1979-1985 (by SOLWIND) having speed more than 500
km/s. To carry out the study we have used the method of time and
spatial correlations. From the study we have found the following:
(1) About 50% CMEs are related with coronal holes; (2) About 15% CMEs
are related with solar flares; (3) About 25% CMEs are associated with
eruptive prominence; and (4) About 10% CMEs are not related with any
solar phenomena. The relationship of CMEs and solar radio bursts are
also studied. In the light of above, we are of the view that there may
be two types of CMEs. The origin of one of them may be related with
coronal holes and that for other may be solar flares and prominences.
---------------------------------------------------------
Title: On periodicity of solar wind phenomena
Authors: Verma, V. K.; Joshi, G. C.
1995sowi.confQ..98V Altcode:
We have investigated the rate of occurrence of solar wind phenomena
observed between 1972-1984 using power spectrum analysis. The data
have been taken from the high speed solar wind (HSSW) streams catalogue
published by Mavromichalaki et al. (1988). The power spectrum analysis
of HSSW events indicate that HSSW stream events have a periodicity of 9
days. This periodicity of HSSW events is 1/3 of the 27 days period of
coronal holes which are the major source of solar wind events. In our
opinion the 9 days period may be the energy build up time to produce
the HSSW stream events.
---------------------------------------------------------
Title: On the Periodicity of Solar Wind Phenomena
Authors: Verma, V. K.; Joshi, G. C.
1995JApAS..16R.387V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Mass Transfer and Surge Activity of 1993MAY14
Authors: Verma, V. K.; Uddin, W.
1995JApAS..16Q.387V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Occurrence Rate of High Speed Solar Wind Events
Authors: Verma, V. K.; Joshi, G. C.
1994SoPh..155..401V Altcode:
We have investigated the rate of occurrence of solar wind phenomena
observed between 1972-1984 using power-spectrum analysis. The data
have been taken from the high-speed solar wind (HSSW) stream catalogue
published by Mavromichalaki, Vassilaki, and Marmatsouri (1988). The
power-spectrum analysis of HSSW events indicates that HSSW stream events
have a periodicity of 9 days. This periodicity of HSSW events is of the
27-day period of coronal holes, which are major sources of solar wind
events. In our opinion, the 9-day period may be the energy build-up
time for coronal hole regions to produce the HSSW stream events.
---------------------------------------------------------
Title: On the North-South Asymmetry of Solar Activity Cycles
Authors: Verma, V. K.
1993ApJ...403..797V Altcode:
We report a study of various solar phenomena occurring in both northern
and southern hemispheres of the Sun for solar cycles 8-22. We have
calculated the N-S asymmetry indices for several solar phenomena and
plotted them against the number of solar cycles. The study indicates
that the N-S asymmetry has a trend of a long-term characteristic time
scale of about 110 yr. An explanation of this N-S asymmetry period
is not available; it may be due to the asymmetric internal magnetic
structure of the Sun.
---------------------------------------------------------
Title: Study of solar type-II radio bursts and Hα flares.
Authors: Verma, V. K.
1992IJRSP..21...97V Altcode:
An analysis of the relationship of solar type-II radio bursts with
Hα flares has been presented. The study shows that 75% of type-II
bursts is associated with bright Hα flares of importance ≤1. The
two-ribbon (TR) Hα flares are 15 times more strongly associated with
type-II bursts than the compact flares. Type-II bursts start 1 - 15
min after the onset of Hα flares. The time interval between start of
type-II bursts and peak of Hα flares is ±5 min. This differs from
the results found by earlier investigators. The 66% of type-II bursts
is associated with flares' bright points in Hα emissions.
---------------------------------------------------------
Title: Study of Periodicities of Solar Nuclear Gamma-Ray Flares
and Sunspots
Authors: Verma, V. K.; Joshi, G. C.; Paliwal, D. C.
1992SoPh..138..205V Altcode:
Here we have carried out a power-spectrum analysis of solar nuclear
gamma-ray (NGR) flares observed by SMM and HINOTORI satellites. The
solar NGR flares show a periodicity of 152 days, confirming the
existence of a 152-158 days periodicity in the occurrence of solar
activity phenomena and also indicating that the NGR flares are a
separate class of solar flares. The power-spectrum analysis of the daily
sunspot areas on the Sun for the period 1980-1982 shows a peak around
159 days while sunspot number data do not show any periodicity (Verma
and Joshi, 1987). Therefore, only sunspot area data should be treated
as an indicator of solar activity and not the daily sunspot number data.
---------------------------------------------------------
Title: Coronal mass ejections and their associations with solar
flares and coronal holes.
Authors: Verma, V. K.
1992IJRSP..21...64V Altcode:
The results of an analysis of the associations of coronal mass ejections
(CMEs) with solar flares and coronal holes are presented. Out of 79
CMEs whose locations and span are known, 10 CMEs circles contain solar
flares. On the other hand, out of 71 CMEs (selected for the study of
an association with coronal holes) 41 CMEs circles contain coronal
holes. The above associations are examined by calculating the Yule's
coefficients of association and found that the CMEs and solar flares
are statistically not associated, while CMEs and coronal holes are
statistically associated. This investigation indicates that CMEs come
from coronal holes.
---------------------------------------------------------
Title: The Distribution of the North-South Asymmetry for the Various
Activity Cycles
Authors: Verma, V. K.
1992ASPC...27..429V Altcode: 1992socy.work..429V
No abstract at ADS
---------------------------------------------------------
Title: Search for a 152-158 days periodicity in the occurrence rate
of solar flares inferred from spectral data of radio bursts
Authors: Verma, V. K.; Joshi, G. C.; Uddin, Wahab; Paliwal, D. C.
1991A&AS...90...83V Altcode:
A power spectrum analysis of the daily number of solar flares producing
type I, II, III, IV, and V radio bursts has been carried out for
the period 1980-1984. The analysis shows that type II and IV radio
bursts confirm the existence of a 152-158 days periodicity in the rate
of occurrence, while type I, III and V radio bursts do not show this
152-158 days periodicity. It is concluded that only type II and IV radio
bursts should be used as a parameter which indicates the solar activity.
---------------------------------------------------------
Title: The Acceleration of Electrons and Ions in Solar Flares
Authors: Verma, V. K.
1991Ap&SS.183..317V Altcode:
We find that gamma-ray line (GRL) emissions start later than the
hard X-ray (HXR) emissions during impulsive and extended solar
flares. Starting delay is more in the case of extended solar flares
suggesting a slow acceleration of electrons and ions, in comparison to
impulsive solar flares which indicate different acceleration mechanism
for impulsive and extended solar flares. We further infer that during
solar flares, electrons and ions are accelerated simultaneously
and the delay between HXR and GRL emissions results mainly due to
differences in acceleration times of electrons and ions to attain
energies required for producing HXR emissions for electrons and GRL
emissions for ions. Therefore, we are of view that a single step
acceleration mechanism may work in solar flares.
---------------------------------------------------------
Title: The Distribution of Sunspots Over the Sun
Authors: Uddin, Wahab; Pande, M. C.; Verma, V. K.
1991Ap&SS.181..111U Altcode:
The distribution of the sunspots for the period 1967 1987 (solar cycles
20 and 21) is presented here. We find that the ±11 20° latitude belt
is most prolific for the occurrence of various spot types irrespective
of magnetic-field ranges. Furthermore, longitudinally sunspots occur
most prolifically at six or more places on the Sun. Spatially 7 9
zones are present in each hemisphere (north or south) of the Sun
where about 50% sunspots occur and occupy only about 4% area of the
Sun. During the above cycles at least 5 flare zones were regularly
present in each hemisphere. The existing models cannot explain these
active zones on the Sun. Thus, the present analysis emphasizes the
need for a new magnetic models of the Sun.
---------------------------------------------------------
Title: On the Association of Solar Proton Events with Other Flare
Manifestations
Authors: Uddin, Wahab; Pande, M. C.; Verma, V. K.
1990BAICz..41..374U Altcode:
The present investigation studied the relation between solar proton
flares and associated optical radio and hard X-ray events. It was
found that proton flares are usually associated with large optical
flares in H-alpha and long-duration type II and IV, microwave and
hard X-ray bursts. The summation curve analysis shows that a sharp
rise in the cumulative flares index seems to be prerequisite for the
occurrence of proton flares. The correlation studies between proton
flares and microwave and proton flares and hard X-ray have also ben
carried out. The results obtained in the present analysis may be used
to predict solar proton flares.
---------------------------------------------------------
Title: Relationship of Coronal Mass Ejection Events with Solar Flares
and Coronal Holes
Authors: Verma, V. K.
1990IAUS..142..450V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the association between coronal mass ejections and coronal
holes.
Authors: Verma, V. K.; Pande, M. C.
1989sasf.confP.239V Altcode: 1989IAUCo.104P.239V; 1988sasf.conf..239V
The coronal mass ejection (CME) data and the data for coronal holes
for the period 1979 - 1982 are compared locationwise. Out of 79 CMEs
whose locations and spans are known, 48 (61%) CMEs are associated with
coronal holes. The authors make a tentative suggestion that probably
the mass ejected during solar flares and active prominences may move
along the open magnetic field of the coronal holes and appear as CMEs.
---------------------------------------------------------
Title: Microwave, hard X-ray bursts and gamma ray emission bursts
from solarflares.
Authors: Verma, V. K.
1988IJRSP..17...45V Altcode:
A study has been carried out on the time delay between microwave (MW)
emissions at 35 GHz, hard X-ray (HXR) emissions and gamma ray (GR)
emissions observed during solar flares. The GR emissions are found to
start about 1 min after the onset of HXR emissions during impulsive
flares and 4 min after the onset of HXR emissions during extended
solar flares, indicating that impulsive and extended solar flares
are two different types of flares and may have different mechanisms
of origin. The onset time delays in GR and HXR emissions are due to
the differences in kinetic energy of electrons to produce GR and HXR
photons. An investigation regarding onset time delays between GR and
MW emissions has also been carried out. The GR emissions are found to
start 1 min after the onset of MW emissions during impulsive flares. The
MW and GR emissions originate from different mechanisms operating
at different heights and are produced by electrons with differing
energies, thus producing time delays. Further, it is observed that MW
emissions may not be produced by relativistic electrons as suggested
by some investigators.
---------------------------------------------------------
Title: On the increase of solar activity in the southern hemisphere
during solar cycle 21
Authors: Verma, V. K.
1988SoPh..114..185V Altcode:
The present paper investigates the north-south asymmetry for major
flares (solar cycles 19 and 20), type II radio bursts (solar cycles
19,20 and 21), white light flares (solar cycle 19,20 and 21), and gamma
ray bursts, hard X-ray bursts and coronal mass ejections (solar cycle
21). The results are compared with the found asymmetry in favour of
the northern hemisphere during solar cycles 19 and 20 in favour of
the southern hemisphere during solar cycle 21.
---------------------------------------------------------
Title: Spatial locations of type II radio burst regions on the Sun.
Authors: Verma, V. K.; Pande, M. C.
1988IJRSP..17....8V Altcode:
The spatial locations of type II radio burst regions on the sun have
been investigated. Latitudewise, 11-20 deg northern and southern belts
are found to be type II prolific. Longitudinally, both the northern and
the southern hemispheres show five to seven active longitudes. Since
type II bursts are associated with most energetic flares, it can be said
that spatially more than ten energetic event zones (EEZs) are present
on the sun and they occupy about 3 percent area of the sun. Study of
solar cycles 20 and 21 shows that at least five EEZs are present in
each hemisphere of the sun. These zones cannot be explained by the
existing models, and the present analysis emphasizes the need for a
new magnetic model of the sun.
---------------------------------------------------------
Title: Possibility of occurrence of solar proton flares in relation
to other phenomena.
Authors: Uddin, W.; Pande, M. C.; Verma, V. K.
1988KodOB...9..223U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the periodicity of solar great hard X-ray bursts, energetic
solar radio bursts and sunspot data.
Authors: Verma, V. K.; Joshi, G. C.
1988KodOB...9..215V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Microwave and hard X-ray emission bursts during solar flares.
Authors: Verma, V. K.
1987IJRSP..16..384V Altcode:
Analysis of time intervals and peak fluxes between hard X-rays (HXRs)
of energies 17-40 keV and solar microwave (MW) bursts observed at 3.75,
9.4, and 17 GHz during impulsive and extended solar flares shows both
simultaneous emission between MW and HXR emissions and delay at onset
and peak. The flares showing simultaneous emission between MW and HXR
emissions may be simple loop flares. The time delay may be due to the
differences in source location, mechanism, and kinetic energies of
electrons required to produce MW and HXR emission bursts. The peak
fluxes of the MW and the HXR emissions are well correlated during
impulsive flares. Radio flux and photon counts/s increase linearly,
suggesting that they may be produced by the same species of accelerated
solar particles.
---------------------------------------------------------
Title: On the Periodicities of Sunspots and Solar Strong Hard
X-Ray Bursts
Authors: Verma, V. K.; Joshi, G. C.
1987SoPh..114..415V Altcode:
In the present investigation, we have carried out power spectrum
analysis of sunspot number and great hard x-ray (GHXR) burst (equal
to or greater than 10,000 counts per second) for a period of about
6 years. The GHXR bursts show a periodicity of about 155 days. On
the other hand, sunspot numbers do not show any periodicity. The GHXR
burst periodicity confirms the existence of a 152-158 days periodicity
in the occurrence of solar energetic events. Further, the GHXR bursts
are showing periodicity independently indicating that the GHXR bursts
are a separate class of X-ray flares.
---------------------------------------------------------
Title: Energetic Flare Zones on the Sun
Authors: Verma, V. K.; Pande, M. C.; Uddin, Wahab
1987SoPh..112..341V Altcode:
In this investigation, we have studied the latitudinal, longitudinal
(northern and southern hemispheric) distributions based on 1737
major flares observed during solar cycles 19 and 20 (see subsequent
paragraphs) and have arrrived at some interesting results which go to
show that as far major flares are concerned latitudewise 11-20° belts,
and longitudewise 5-8 places are most prolific in producing major flares
in each hemisphere. During the above cycles at least 5 flare zones are
present in each hemisphere. In fact these zones seem to produce more
than 50% of the total number of energetic flares investigated by us
and occupy only <4% area of the Sun.
---------------------------------------------------------
Title: Relationship of solar gamma ray emissions with microwaves
and other radio bursts.
Authors: Verma, V. K.
1987IJRSP..16..281V Altcode:
The relationships of solar gamma ray (GR) emissions with microwave
(MW) and other radio bursts have been studied. The GR emissions are
found to start about 1-2 min after the onset of MW emissions (on 17
GHz) or about 0.5 min before the peak of MW emissions. This time delay
may be due to differences in acceleration times for accelerating the
electrons for MW emissions and protons, ions and nuclei for gamma ray
(also line) emissions. Further, the GR emission flares are found to be
associated fairly well with type-II and type-IV radio bursts while the
gamma ray line (GRL) emission flares show higher association with the
type-II and type-IV radio bursts. The type-II bursts start about 6 min
after the onset of GR emissions while the type-IV bursts start about 2
min before the onset of GR emissions, which show that the GR emissions
and the type-II (also type-IV) may not be produced simultaneously by
shock waves.
---------------------------------------------------------
Title: The Distribution of Sunspots Over the Sun
Authors: Uddin, W.; Pande, M. C.; Verma, V. K.
1987BASI...15...18U Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Relation Between Gamma-Ray and Hard X-Ray Emission Bursts
during Solar Flares
Authors: Verma, V. K.
1987BASI...15Q..19V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the increase of solar activity in the Southern Hemisphere
during solar cycle 21
Authors: Verma, V. K.
1987SoPh..114..185V Altcode:
The north-south asymmetry for major flares (solar cycle 19 and 20),
type II radio bursts (solar cycles 19, 20, and 21), white light flares
(solar cycles 19, 20, and 21), and gamma ray bursts, Hard X-ray bursts,
and coronal mass ejections (solar cycle 21) is investigated. Results
indicate that the asymmetry occurs in the Northern Hemisphere during
cycles 19 and 20, and that it favors the Southern Hemisphere during
cycle 21. It is suggested that the change in asymmetry from the Northern
to the Southern Hemisphere may be related to the sun's interior.
---------------------------------------------------------
Title: On Association of Radio Emission with Solar Surges
Authors: Verma, V. K.
1986SoPh..106...67V Altcode:
About 45% non-flare surges are found to be associated with radio bursts
inferred from spectral data. Associated surges are mostly accompanied
by type I (24%) and type III (29%) bursts.
---------------------------------------------------------
Title: On the dependence of solar flare occurrence on sunspot polarity
Authors: Verma, V. K.; Shelke, R. N.
1985BASI...13..243V Altcode:
The possibility of predicting flare occurrence on the sun has been
examined. It is noticed that the p-polarity dominant spot groups
are more productive of flares than the f-polarity dominant spot
groups. This high productivity of p-polarity dominant spot groups
has been interpreted in terms of :(1) high rates of new magnetic
flux eruption within the p-polarity dominant spot groups; and (2)
newly erupted magnetic flux triggering flares (cf. Heyvaerts et al.,
1977). Moreover, the productivities of all group types are dependent
on the magnetic field strength of the spot groups.
---------------------------------------------------------
Title: Longitudinal Distribution of the Hard X-Ray Bursts on the Sun
Authors: Verma, V. K.; Pande, M. C.
1985SoPh...99..285V Altcode:
The analysis of 315 hard X-ray bursts (HXR) producing solar flares
observed by Hinotori satellite shows that the HXR bursts occur
most prominently at 110°, 140°, 290°, and 320° longitude,
respectively. These longitudes are not only prolific in producing
flares in number but also in producing flares with large photon counts.
---------------------------------------------------------
Title: On the Solar Surge Association with Microwave and Hard X-Ray
Emission Bursts
Authors: Verma, V. K.
1985SoPh...97..381V Altcode:
It is found that 20% solar surges are associated with microwave bursts
(2800-15000 MHz) and also that solar surges are not associated with
hard X-ray bursts (17-40 keV).
---------------------------------------------------------
Title: Time delay between H-alpha and soft X-ray emissions during
solar flares
Authors: Verma, V. K.; Pande, M. C.
1985BASI...13..148V Altcode:
A statistical analysis of time delays between H-alpha and soft X-ray
(SXR) emissions at onset and peak respectively during solar flares
is presented. The authors find that at the onset of flares SXR
emission starts simultaneously or up to two min earlier than H-alpha
emissions. At peak flux the SXR emission is found to be peaked between
2 min before to 3 min after the H-alpha emissions.
---------------------------------------------------------
Title: Time Delay Between Hα and Hard X-Ray Emissions during
Impulsive Solar Flares
Authors: Verma, V. K.; Pande, M. C.
1985SoPh...97..107V Altcode:
This investigation shows that statistically there are significant time
delays between Hα and hard X-ray (HXR) emissions during solar flares;
most impulsive flares produce HXR emissions up to ∼1 min before and
up to 2 min after the onset of Hα emission. HXR emissions are also
found to be peaked up to 2 min before the Hα emissions.
---------------------------------------------------------
Title: On the location of solar active longitudes
Authors: Shelke, R. N.; Verma, V. K.
1985BASI...13...53S Altcode:
The longitudinal distributions of sudden ionospheric disturbances
producing active regions with high flares activity and/or with at
least one high energy flare particle event (PCA or GLE) have been
examined. These active regions appear to cluster at four active
longitudes, separated by a longitudinal distance of about 60 and
180 deg. It is also inferred that these active longitudes drift in
position by about 21.55 deg per year, thus exhibiting almost rigid
rotation. Quasi-periodicities of 2.3 to 5.3 yr are also seen in 12
Fourier spectra of time series of high flare activity regions in 30 deg
wide longitude range. These periodicities have been interpreted as due
to drifting of four active longitudes having 60 and 120 longitudinal
separations.
---------------------------------------------------------
Title: Microwave and hard X-ray emission during solar flare of 19
Oct. 1981.
Authors: Verma, V. K.
1984IJRSP..13..159V Altcode:
Time correlation study of a double ribbon flare, observed on Oct. 19,
1981, in the light of H-alpha, microwave, and hard X-ray data is
presented. The kinetic energy of electrons required to emit hard X-rays
is nearly 10,000 times that of those electrons which produce microwave
emission. The magnetic field and source size of the microwave emission
region are found to be 375 gauss and 7 arcsec, respectively, and the
kinetic energy involved in flare strand separation turns out to be
6.2 x 10 to the 27th erg/sec.
---------------------------------------------------------
Title: Longitudinal Distribution of the Cool Solar Surges
Authors: Verma, V. K.
1984SoPh...94..155V Altcode:
This investigation shows that solar surges are poorly associated with
sudden ionospheric disturbances (X-ray) implying that solar surge
material is cool and does not heat the corona. The investigation also
shows that solar surges are most prolific at longitudes 80°, 110°,
260°, and 290°.
---------------------------------------------------------
Title: On the activation of a quiescent prominence
Authors: Verma, V. K.
1983BASI...11..159V Altcode:
During the observations of a quiescent prominence of 1981 November
27, the prominence got activated and mass transfer to another active
centre took place with an average velocity of 32 km s<SUP>-1</SUP>
along a looped path. The total mass transferred to the nearby active
centre is estimated to be 6.75×10<SUP>15</SUP> g.
---------------------------------------------------------
Title: Twisted Surge of 1981DEC25
Authors: Verma, V. K.
1983BASI...11...70V Altcode:
Photographic observations and the morphological behaviour of the surge
prominence of importance class 1 recorded with a 0.7 Å passband H-alpha
filter on 1981 December 25 are described. From these observations
height, mass, velocity, mechanical energy and magnetic field of the
ejected surge material are estimated.
---------------------------------------------------------
Title: Double Ribbon Flare of 1981OCT19
Authors: Verma, V. K.; Pande, M. C.
1983BASI...11...38V Altcode:
Photographic observations with a 0.7 Å passband H-alpha filter of
the double ribbon flare which occurred near Halle plage region 17926
on 1981 October 19 are described. From the observed data, the authors
have estimated the separation and the velocity of separation of the
two strands. An estimate of the magnetic field associated with the
flare is also given.
---------------------------------------------------------
Title: Quiescent prominence of 1981 November 27.
Authors: Verma, V. K.
1983BASI...11...91V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Surge Prominence of 1981NOV19
Authors: Verma, V. K.; Pande, M. C.
1982BASI...10..211V Altcode:
Time-lapse photographic observations with 0.7 Å passband H-alpha
filter and the morphological behaviour of the surge prominence recorded
on 1981 November 19 have been described. The surge was recorded both
in the ascending and descending phases. From these observations, the
height, mass, velocity, magnetic field and mechanical energy involved
in ejecting the mass material of the surge prominence were estimated.
