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Browsing IIAP Publications by Title

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  • Hanle Effect with Angle-dependent Partial Frequency Redistribution in Threedimensional Media 
    Anusha, L. S (American Astronomical Society, 2023-06-01)
    There has been a constant improvement in the observational measurement of linear polarization in chromospheric spectral lines in the last three decades. However, modeling polarized profiles of these lines still remains ...
  • Hanle effect with angle-dependent partial redistribution 
    Nagendra, K. N; Frisch, H; Faurobert, M (The European Southern Observatory, 2002-11)
    The polarized line transfer equation for the Hanle effect is solved in the framework of an exact partial frequency redistribution (PRD) theory developed by Bommier (1997a,b). In that theory the effect of collisions on the ...
  • The Hanle effect with partial frequency redistribution. Construction of a frequency-dependent polarization matrix and numerical solution by a PALI method 
    Sampoorna, M; Nagendra, K. N; Frisch, H (Elsevier, 2008-09)
    The polarized approximate lambda iteration (PALI) technique developed for the weak field Hanle effect relies on the decomposition of the Stokes parameters I, Q and U into six cylindrically symmetrical components. It has ...
  • Hanle-Zeeman Redistribution Matrix. I. Classical Theory Expressions in the Laboratory Frame 
    Sampoorna, M; Nagendra, K. N; Stenflo, J. O (University of Chicago Press, 2007-07)
    Polarized scattering in spectral lines is governed by a 4×4 matrix that describes how the Stokes vector is scattered and redistributed in frequency and direction. Here we develop the theory for this redistribution matrix ...
  • Hanle-Zeeman Redistribution Matrix. II. Comparison of Classical and Quantum Electrodynamic Approaches 
    Sampoorna, M; Nagendra, K. N; Stenflo, J. O (University of Chicago Press, 2007-12)
    The Hanle-Zeeman redistribution matrix accounts for the intricately coupled correlations in frequency, angle, and polarization between the incoming and outgoing radiation and embodies the physics of the scattering process. ...
  • Hanle-Zeeman Redistribution Matrix. III. Solution of the Polarized Line Formation Problem 
    Sampoorna, M; Nagendra, K. N; Stenflo, J. O (The American Astronomical Society, 2008-05)
    The polarized radiative transfer equation is solved numerically, taking into account both the Zeeman absorption matrix and the Hanle-Zeeman redistribution matrix, to obtain line profiles for arbitrary magnetic field ...
  • Hanle-Zeeman Scattering Matrix for Magnetic Dipole Transitions 
    Megha, A; Sampoorna, M; Nagendra, K. N; Sankarasubramanian, K (IOP Publishing, 2017-07)
    The polarization of the light that is scattered by the coronal ions is influenced by the anisotropic illumination from the photosphere and the magnetic field structuring in the solar corona. The properties of the coronal ...
  • A Hard gamma-ray flare from 3C 279 in 2013 December 
    Paliya, Vaidehi S; Diltz, Chris; Bottcher, Markus; Stalin, C. S; Buckley, David (IOP Publishing, 2016-01)
    The blazar 3C 279 exhibited twin γ -ray fl ares of similar intensity in 2013 December and 2014 April. In this work, we present a detailed multi-wavelength analysis of the 2013 December fl aring event. Multi-frequency ...
  • Hard X-ray characteristics of solar flares using electron Monte-Carlo calculations and beamed thick target model 
    Rausaria, R. R (Springer Netherlands, 1992-08)
    The experimental results of X-ray bursts with spectral characteristics, spatial distribution, fast time variations, polarization, and directivity measurements carried out with Intercosmos, PVO/ISEE-3 spacecrafts, imaging ...
  • Hard X-ray flux variations in AGN from NuSTAR 
    Priyanka Rani; Stalin, C. S (Astronomical Society of India, 2015-04)
    We present here our results on the hour like time scale Xray flux variations in a sample of active galactic nuclei using data from the Nuclear Spectroscopic Telescope Array (NuSTAR). We find that in the 3−79 keV band, ...
  • Hard-Core Bosons in a Zig-Zag Optical Superlattice 
    Dhar, A; Mishra, T; Pai, R. V; Mukerjee, S; Das, B. P (American Physical Society, 2013-11-21)
    We study a system of hard-core bosons at half-filling in a one-dimensional optical superlattice. The bosons are allowed to hop to nearest- and next-nearest-neighbor sites. We obtain the ground-state phase diagram as a ...
  • Harmonically related decimetric fine structures 
    Sawant, H. S; Fernandes, F. C. R; Karlický, M; Mészárosová, H; Krishan, V; Cecatto, J. R; Madsen, F. R. H; Andrade, M. C (Elsevier B.V., 2006-02)
    We report rare events, above 1000 MHz, in which emission at the fundamental and at second harmonic frequencies show nearly identical fine structures. These high resolution observations are obtained from the Brazilian Solar ...
  • HCT/HESP study of two carbon stars from the LAMOST survey 
    Shejeelammal, J; Goswami, A; Shi, Jianrong (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    Carbon stars, enhanced in carbon and neutron-capture elements, provide a wealth of information about the nucleosynthesis history of the Galaxy. In this work, we present the first ever detailed abundance analysis of the ...
  • HD 105262: a high latitude metal-poor post-AGB. A supergiant with large proper motion 
    Reddy, B. E; Parthasarathy, M; Sivarani, T (European Southern Observatory, 1996-09)
    The large proper motion post-AGB supergiant stars are very rare. HD 105262 is a high galactic latitude (+72deg) A-type star with large proper motion (0.057arcsec/year) and high c1-index. Earlier, it was classified as a ...
  • HD 147010:The AP star in the reflection nebula vdB 102 in upper scorpius region 
    Kameswara Rao, N; Rajamohan, R (Indian Academy of Sciences, 1982-09)
    HD 147010, which is in the reflection nebula vdB 102, has been found to be a hot Ap silicon star rather than a normal A supergiant. From the UBV and JHK photometry of the star, color excess E(B-V) of 0.29 and the ratio of ...
  • HD 22403: a New Variable with Ca II H and K Emission 
    Raveendran, A. V; Mohin, S; Mekkaden, M. V (Konkoly Observatory, 1985-03-26)
  • HD 34700: A new T Tauri double-lined spectroscopic binary 
    Arellano, F. A; Giridhar, S (The European Southern Observatory, 2003-09)
    We find the star HD 34700 to be a double-lined spectroscopic binary. We also identify it as a weak-line T Tauri object. The spectra of both components are very similar and both show the Li I feature at 6708 Å. Strong ...
  • HD 77361: a new case of super Li-rich K giant with anomalous low C-12/C-13 ratio 
    Bharat Kumar, Y; Reddy, B. E (The American Astronomical Society, 2009-09)
    Results from high-resolution spectroscopic analysis of HD77361 are reported. LTE analysis shows that HD77361 is a K giant of atmospheric parameters: T-eff = 4580 +/- 75 K, log g = 2.5 +/- 0.1, and xi(t) = 1.40 +/- 0.5 km ...
  • HD 81410 - A new RS CVn binary 
    Raveendran, A. V; Mekkaden, M. V; Mohin, S (Royal Astronomical Society, 1982-05)
    B and V photometry of HD 81410 obtained on 34 nights between January 3 and March 14 of 1981 is presented. In both B and V, the amplitudes are found to be approximately 0.15 mag. It is also found that a 12.86833 day period ...
  • HD209621: abundances of neutron-capture elements 
    Goswami, A; Aoki, W (Blackwell Publishing, 2010-05)
    High-resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD 209621. We have derived a metallicity of ...

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