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Browsing IIAP Publications by Title

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  • Flares associated with abnormal rotation rates: Longitudinal minimum separation of leading and following sunspots 
    Hiremath, K. M; Suryanarayana, G. S; Lovely, M. R (EDP Sciences, 2005-07)
    Using six years (1969-1974) of data of sunspot groups from the white light pictures of the Kodaikanal Observatory, we compute rotation rates of the leading and the following sunspots and the rate of change of longitudinal ...
  • The flares associated with the abnormal rotation rates of the bipolar sunspots: Reconnection probably below the surface 
    Hiremath, K. M; Suryanarayana, G. S (The European Southern Observatory, 2003-12)
    We use the observations of Kodaikanal observatory white light pictures to study the association between the rotation rates of the bipolar sunspots and triggering of the flares. For the years 1969-1974, we compute daily ...
  • The Flares Associated with the Dynamics of the Sunspots 
    Hiremath, K. M (Indian Academy of Sciences, 2006-09)
    In the present study, we consider six years data of spot groups that have well developed leading and following spots obtained from the Kodaikanal Observatory white light pictures and occurrence of Hα flares. From the daily ...
  • Flares before and after coronal mass ejections 
    Suryanarayana, G. S (IOP Publishing, 2018-03)
    Flare characteristics such as the flare occurrence number density and the distribution of peak flux as well as duration of flares occurring on either side of a coronal mass ejection (CME) onset time are studied. While the ...
  • Flares on AM Canum Venaticorum 
    Marar, T. M. K; Padmini, V. N; Seetha, S; Narayanan Kutty, K. R; Kasturirangan, K; Rao, U. R; Bhattacharyya, J. C (European Southern Observatory, 1988-01)
    AM CVn, an interacting binary system consisting of two helium white dwarfs, has been classified as a nova-like object. Normally it exhibits only small amplitude modulations of 0.05 mag with a 1051 s periodicity. The authors ...
  • Flash Ionization Signatures in the Type Ibn Supernova SN 2019uo 
    Gangopadhyay, A; Misra, K; Hiramatsu, D; Wang, Shan-Qin; Hosseinzadeh, G; Wang, Xiaofeng; Valenti, Stefano; Zhang, Jujia; Howel, D. A; Arcavi, Iair; Anupama, G. C; Burke, Jamison; Dastidar, Raya; Koichi Itagaki, Koichi; Kumar, Brajesh; Kumar, B; Li, Long; McCully, Curtis; Mo, Jun; Pandey, S. B; Pellegrino, Craig; Sa, Hanna; Sahu, D. K; Pankaj Sanwal; Singh, A; Singh, M; Zhang, Jicheng; Zhang, Tianmeng; Zhang, Xinhan (IOP Publishing, 2020-02-01)
    We present photometric and spectroscopic observations of the type Ibn supernova (SN) 2019uo, the second ever SN Ibn with flash ionization (He ii, C iii, N iii) features in its early spectra. SN 2019uo displays a rapid ...
  • Flat rotation curves: A result of the helical inverse cascade in turbulent media? 
    Prabhu, R. D; Krishan, V (The American Physical Society, 1994-06)
    We have modeled the rotation curves of 21 galaxies observed by Amram et al. (1992), by combining the effects of rigid rotation, gravity, and turbulence. The main motivation behind such modeling is to study the formation ...
  • A flattening in the optical light curve of SN 2002ap 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Sahu, D. K; Pandey, J. C (Royal Astronomical Society, 2003-04)
    We present the UBVRcIc broad-band optical photometry of the Type Ic supernova SN 2002ap obtained during 2002 February 6-March 23 in the early decline phases and also later on 2002 August 15. Combining these data with the ...
  • A Flattening in the Optical Light Curve of SN 2002ap. 
    Pandey, S. B; Anupama, G. C; Sagar, R; Bhattacharya, D; Sahu, D. K; Pandey, J. C (Blackwell Publishing, Edinburge, UK, 1994)
  • Flexure compensation simulation tool for TMT-WFOS spectrograph 
    Surya, Arun; Radovan, Matthew; Sivarani, T; Sriram, S; Devika, Divakar; Fucik, Jason (SPIE--The International Society for Optical Engineering, 2018-07)
    The Wide Field Optical Spectrograph (WFOS) is one of the first-light instruments of Thirty Meter Telescope. It is a medium resolution, multi object, wide field optical spectrograph. Since 2005 the conceptual design of the ...
  • Flow of Gas along a Magnetic field with Time-Dependent Geometry 
    Hasan, S. S; Venkatakrishnan, P (Indian Institute of Astrophysics, Bangalore, 1980)
    The flow of gas along a magnetic field with time dependent geometry has been studied. It is seen that the velocity of the flow in the direction of the magnetic field depends both on the magnitude of the velocity of flow ...
  • Flows and waves in braided solar coronal magnetic structures 
    Pant, V; Datta, A; Banerjee, D (IOP Publishing, 2015-03-01)
    We study the high frequency dynamics in the braided magnetic structure of an active region (AR 11520) moss as observed by the High-Resolution Coronal Imager (Hi-C). We detect quasi-periodic flows and waves in these structures. ...
  • Fluorine detection in hot extreme helium stars 
    Bhowmick, A; Pandey, G; Lambert, D. L (Springer, 2020-12)
    The origin and evolution of hydrogen-deficient stars are not yet adequately understood. Their chemical peculiarities, along with hydrogen-deficiency, makes them stand out from the rest and sheds light on their possible ...
  • Fluorine in R Coronae Borealis Stars 
    Pandey, G; Lambert, D. L; Kameswara Rao, N (Astronomical Society of the Pacific, 2008)
    Neutral fluorine lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is ...
  • Fluorine in R Coronae Borealis Stars 
    Pandey, G; Lambert, D. L; Kameswara Rao, N (University of Chicago Press, 2008-02)
    Neutral fluorine (F i) lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine ...
  • Flux and polarization variability of OJ 287 during the early 2016 outburst 
    Rakshit, S; Stalin, C. S; Muneer, S; Neha, S; Paliya, Vaidehi S (IOP Publishing, 2017-02-01)
    The gamma-ray blazar OJ 287 was in a high activity state during 2015 December–2016 February. Coinciding with this high brightness state, we observed this source for photometry on 40 nights in R-band and for polarimetry on ...
  • Flux and spectral variability of Mrk 421 during its moderate activity state using NuSTAR: Possible accretion disc contribution? 
    Mondal, S; Priyanka Rani; Stalin, C. S; Chakrabarti, S. K; Rakshit, S (EDP Sciences, 2022-07)
    Context. The X-ray emission in BL Lac objects is believed to be dominated by synchrotron emission from their relativistic jets. However, when the jet emission is not strong, one could expect signatures of X-ray emission ...
  • Flux emergence in the solar active region NOAA 11158: the evolution of net current 
    Vemareddy, P; Venkatakrishnan, P; Karthikreddy, S (IOP Publishing, 2015-09)
    We present a detailed investigation of the evolution of observed net vertical current using a time series of vector magnetograms of the active region (AR) NOAA 11158 obtained from the Helioseismic and Magnetic Imager. We ...
  • Flux tube model in the solar atmosphere 
    Sen, Samrat; Mangalam, A (Cambridge University Press, 2018-02)
    We construct two classes of the magnetohydrostatic equilibria of the axisymmetric flux tubes with twisted magnetic fields in the stratified solar atmosphere that span from the photosphere to the transition region. We built ...
  • Fluxvector Splitting of the Inviscid Radiation Gas Dynamic Equations 
    Peraiah, A (Indian Institute of Astrophysics, Bangalore, 1980)
    We have analysed various schemes for the iterative simultaneous solution of the inviscid gas dynamic equations. We have considered the problem from the point of view of the stellar atmospheres. The difference between ...

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