IIA Institutional Repository: Recent submissions

  • Multi-dimensional polarized radiative transfer: methods and solar applications 
    Anusha, L. S; Nagendra, K. N (Astronomical Society of the Pacific, 2014-10)
    Observations of the Sun using modern telescopes as well as numerical simulations of the Sun reveal existence of enormous inhomogeneous structures in the solar atmosphere. The polarized spectrum of the Sun (Second Solar ...
  • Chemical analysis of a carbon-enhanced very metal-poor star: CD-27 14351 
    Drisya, K; Goswami, A; Masseron, T (IOP Publishing, 2017-01-01)
    We present, for the first time, an abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high-resolution (R ~ 48,000) FEROS spectrum. Our abundance analysis performed using local thermodynamic ...
  • Triggering The Birth of New Cycle’s Sunspots by Solar Tsunami 
    Dikpati, M; McIntosh, S.W; Chatterjee, Subhamoy; Banerjee, D; Yellin-Bergovoy, Ron; Srivastava, A (Springer Nature, 2019-02-14)
    When will a new cycle’s sunspots appear? We demonstrate a novel physical mechanism, namely, that a “solar tsunami” occurring in the Sun’s interior shear-fluid layer can trigger new cycle’s magnetic flux emergence at high ...
  • The distribution and kinematics of interstellar O VI in the milky way 
    Sarma, R; Pathak, A; Murthy, J; Sarma, J. K (Oxford University Press on behalf of the Royal Astronomical Society, 2017-02)
    We present the results of a survey of interstellar O VI absorption in the Milky Way (MW) towards 69 stars in the Large Magellanic Cloud obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). The integrated MW ...
  • Polarized line formation with angle-dependent partial frequency redistribution 
    Sampoorna, M (Astronomical Society of the Pacific, 2014-10)
    The linear polarization of spectral lines seen in the solar limb observations is created by the scattering of the anisotropic radiation field by atoms and molecules. The partial frequency redistribution (PRD) effects in ...
  • Signature of extended solar cycles as detected from Ca ii K synoptic maps of Kodaikanal and Mount Wilson Observatory 
    Chatterjee, Subhamoy; Banerjee, D; McIntosh, S.W; Leamon, Robert J; Dikpati, Mausumi; Srivastava, Abhishek K; Bertello, L (IOP Publishing, 2019-03-20)
    In recent years there has been a resurgence of the study of extended solar cycles (ESCs) through observational proxies mainly in extreme ultraviolet. But most of them are limited only to the space-based era covering only ...
  • The evolution of the Milky Way: new insights from open clusters 
    Reddy, A. B. S; Lambert, D. L; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2016-12)
    We have collected high-dispersion echelle spectra of red giant members in the 12 open clusters (OCs) and derived stellar parameters and chemical abundances for 26 species by either line equivalent widths or synthetic ...
  • Modeling Repeatedly Flaring δ Sunspots 
    Chatterjee, Piyali; Hansteen, V; Carlsson, M (The American Physical Society, 2016-03)
    Active regions (ARs) appearing on the surface of the Sun are classified into α , β , γ , and δ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the δ ...
  • Open and closed magnetic configurations of twisted flux tubes 
    Sen, Samrat; Mangalam, A (IOP Publishing, 2019-06-01)
    We construct two classes of magnetohydrostatic (MHS) equilibria for an axisymmetric vertical flux tube spanning from the photosphere to the lower part of the transition region within a realistic stratified solar atmosphere ...
  • Formation and eruption of sigmoidal satructure from a weak field region of NOAA 11942 
    Vasantharaju, N; Vemareddy, P; Ravindra, B; Doddamani, V. H (IOP Publishing, 2019-04-01)
    Using observations from the Solar Dynamics Observatory, we studied an interesting example of a sigmoid formation and eruption from small-scale flux-canceling regions of active region (AR) 11942. Through an analysis of ...
  • Modelling dust scattering in our galaxy 
    Murthy, J (Oxford University Press on behalf of the Royal Astronomical Society, 2016-06)
    I have used Monte Carlo models with multiple scattering to predict the dust scattered light from our Galaxy and have compared the predictions with data in two ultraviolet bands from the Galaxy Evolution Explorer spacecraft. ...
  • Polarimetric and photometric investigation of the dark globule LDN 1225: distance, extinction law, and magnetic fields 
    Eswaraiah, C; Lai, Shih-Ping; Ma, Yuehui; Anil K. Pandey; Jose, J; Chen, Zhiwei; Samal, M. R; Wang, Jia-Wei; Sharma, S; Ojha, D. K (IOP Publishing, 2019-04-10)
    We present results based on the optical R-band observations of the polarization of 280 stars distributed toward the dark globule LDN 1225. Parallaxes from Gaia data release 2 along with the polarization data of ~200 stars ...
  • Prospect for UV observations from the moon. III. assembly and ground calibration of lunar ultraviolet cosmic imager (LUCI) 
    Mathew, J; Nair, B. G; Safonova, M; Sriram, S; Prakash, A; Mayuresh, Sarpotdar; Ambily, S; Nirmal, K; Sreejith, A. G; Murthy, J; Kamath, P. U; Kathiravan, S; Prasad, B. R; Brosch, Noah; Kappelmann, Norbert; Gadde, Nirmal Suraj; Narayan, Rahul (Springer, 2019-03)
    The Lunar Ultraviolet Cosmic Imager (LUCI) is a near-ultraviolet (NUV) telescope with all-spherical mirrors, designed and built to fly as a scientific payload on a lunar mission with Team Indus—the original Indian entry to ...
  • Line identifications of type I supernovae: on the detection of Si II for these hydrogen-poor events 
    Parrent, J. T; Milisavljevic, D; Soderberg, A. M; Parthasarathy, M (IOP Publishing, 2016-03)
    Here we revisit line identifications of type I supernovae (SNe I) and highlight trace amounts of unburned hydrogen as an important free parameter for the composition of the progenitor. Most one-dimensional stripped-enve ...
  • India’s participation in IAU over the years 
    Mallik, D. C. V (Cambridge University Press, 2018-12)
    India was still a British colony when the International Astronomical Union was born in 1919. India did not have a national science academy nor a national research council at the time. The Royal Society, London, which was ...
  • The first GeV outburst of the radio-loud narrow-line Seyfert 1 galaxy PKS 1502+036 
    Paliya, Vaidehi S; Stalin, C. S (IOP Publishing, 2016-03)
    The γ-ray-loud narrow-line Seyfert 1 (γ-NLSy1) galaxy PKS 1502+036 (z = 0.409) exhibited its first γ-ray outburst on 2015 December 20. In the energy range of 0.1–300 GeV, the highest flux measured by the Fermi-Large Area ...
  • Neutron star physics in the square kilometre array era: an Indian perspective 
    Konar, S; Bagchi, Manjari; Bandyopadhyay, Debades; Banik, Sarmistha; Bhattacharya, D; Bhattacharyya, S; Gangadhara, R. T; Gopakumar, A; Gupta, Y; Joshi, B. C; Maan, Yogesh; Maitra, Chandreyee; Mukherjee, D; Pai, Archana; Paul, B; Ray, A; Sutaria, F. K (Indian Academy of Sciences, 2016-12)
    It is an exceptionally opportune time for astrophysics when a number of next-generation mega-instruments are poised to observe the Universe across the entire electromagnetic spectrum with unprecedented data quality. The ...
  • Interstellar medium and star formation studies with the square kilometre array 
    Manoj, P; Vig, S; Maheswar, G; Kamath, U. S (Indian Academy of Sciences, 2016-12)
    Stars and planetary systems are formed out of molecular clouds in the interstellar medium. Although the sequence of steps involved in star formation are generally known, a comprehensive theory which describes the details ...
  • UVIT open cluster study. I. detection of a white dwarf companion to a blue straggler in M67: evidence of formation through mass transfer 
    Sindhu, N; Subramaniam, A; Jadhav, V. V; Chatterjee, Sourav; Geller, Aaron M; Knigge, Christian; Leigh, Nathan; Puzia, Thomas H; Shara, Michael; Simunovic, Mirko (IOP Publishing, 2019-09-01)
    The old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in ...
  • Dark Matter Objects: Possible New Source of Gravitational Waves 
    Sivaram, C; Arun, K (Springer, 2019-10)
    Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier ...

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