IIA Institutional Repository: Recent submissions

  • Ensemble Average of Three-dimensional Minkowski Tensors of a Gaussian Random Field in Redshift Space 
    Appleby, S; Joby, P. K; Pravabati, C; Park, C (IOP Publishing, 2019-11-20)
    We present the ensemble expectation values for the translation-invariant, rank-2 Minkowski tensors in three dimensions, for a linearly redshift-space-distorted Gaussian random field. The Minkowski tensors W1 0,2, W2 0,2 ...
  • Toward precision radial velocity measurements using Echelle spectrograph at VainuBappu Telescope 
    Chamarthi, Sireesha; Banyal, R. K; Sriram, S (SPIE-The International Society for Optical Engineering, 2019-04)
    The Echelle spectrograph operating at Vainu Bappu Telescope is a general purpose instrument designed for high-resolution spectroscopy. It is being considered for precision Doppler measurements without altering the existing ...
  • Properties of radio-loud quasars in the Sloan Digital Sky Survey 
    Gaur, H; Gu, M; Ramya, S; Guo, H (EDP Sciences, 2019-11)
    We present a study of a sample of 223 radio-loud quasars (up to redshift < 0.3) in order to investigate their spectral properties. Twenty-six of these radio-loud quasars are identified as flat-spectrum radio quasars (FSRQs), ...
  • Optical and X-ray studies of three polars: RX J0859.1 + 0537, RX J0749.1–0549, and RX J0649.8–0737 
    Joshi, Arti; Pandey, J. C; Singh, K. P; Anupama, G. C; Singh, H. P (Oxford University Press on behalf of the Royal Astronomical Society, 2020-01)
    We present optical photometric and spectroscopic observations, and an analysis of archival X-ray data of three polars: RX J0859.1+0537, RX J0749.1–0549, and RX J0649.8–0737. Optical light curves of these three polars reveal ...
  • Simultaneous longitudinal and transverse oscillations in filament threads after a failed eruption 
    Mazumder, R; Pant, V; Manuel Luna; Banerjee, D (EDP Sciences, 2020-01)
    Context. Longitudinal and transverse oscillations are frequently observed in the solar prominences and/or filaments. These oscillations are excited by a large-scale shock wave, impulsive flares at one leg of the filament ...
  • Modeling approaches in helioseismology 
    Rajaguru, S. P (Cambridge University Press, 2015)
    The theory of hydrodynamics or, where necessary, magneto hydrodynamics, provides an appropriate mathematical framework to study solar and stellar oscillations. Well-developed hydrodynamic descriptions of global oscillations ...
  • Optical spectroscopy of Galactic field classical Be stars 
    Banerjee, G; Mathew, B; Paul, K. T; Subramaniam, A; Bhattacharyya, S; Anusha, R (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    In this study, we analyse the emission lines of different species present in 118 Galactic field classical Be stars in the wavelength range of 3800–9000 Å. We re-estimated the extinction parameter (AV) for our sample stars ...
  • Multiwavelength study of different flaring and low-activity states of blazar 4C+21.35 
    Bhattacharya, D; Krishna Mohana, A; Bhattacharyya, S; Bhatt, N; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    Blazars, a class of active galactic nuclei, emit over the entire accessible electromagnetic spectrum and modelling of their broad-band spectral energy distribution (SED) is the key to constrain the underlying emission ...
  • Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud 
    Omkumar, A. O; Subramanian, S; Niederhofer, Florian; Diaz, J; Cioni, Maria-Rosa L; Youssouf, Dalal El; Bekki, K; de Grijs, R; van Loon, J. T (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    Recent observational studies identified a foreground stellar sub-structure traced by red clump (RC) stars (∼12 kpc in front of the main body) in the eastern regions of the Small Magellanic Cloud (SMC) and suggested that ...
  • A multiwavelength study of the dual nuclei in Mrk 212 
    Rubinur, K; Kharb, P; Das, M; Rahna, P. T; Honey, M; Paswan, A; Vaddi, S; Murthy, J (Oxford University Press on behalf of the Royal Astronomical Society, 2021-01)
    We present radio observations of the galaxy merger remnant Mrk 212 with the Karl G. Jansky Very Large Array (VLA) and the upgraded Giant Meter Radio Telescope (uGMRT). Mrk 212 has two previously known radio sources associated ...
  • AstroSat soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst 
    Singh, K. P; Girish, V; Pavana, M; Ness, J.-U; Anupama, G. C; Orio, M (Oxford University Press on behalf of the Royal Astronomical Society, 2021-02)
    Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the symbiotic recurrent nova V3890 Sgr. The first observing run, 8.1–9.9 d after the outburst, initially showed a stable ...
  • The Formation and Evolution of Bars, and Its Impact on Galaxy Dynamics 
    Kataria, Sandeep Kumar (Indian Institute of Astrophysics, 2019-07)
    Observations of galaxies show that in the nearby universe we see that approximately 2/3 of the disk galaxies are barred ones (Eskridge et al., 2000). The formation and evolution scenarios of bars are mainly studied with ...
  • Dust reverberation mapping of Z229–15 
    Mandal, A. K; Rakshit, S; Stalin, C. S; Wylezalek, D; Patig, M. K; Sagar, R; Mathew, B; Muneer, S; Pal, I (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    We report results of the dust reverberation mapping (DRM) on the Seyfert 1 galaxy Z229–15 at z = 0.0273. Quasi-simultaneous photometric observations for a total of 48 epochs were acquired during the period 2017 July to ...
  • Multiwavelength analysis of low surface brightness galaxies to study possible dark matter signature 
    Bhattacharjee, P; Majumdar, P; Mousumi Das; Das, Subinoy; Joarder, P. S; Biswas, Sayan (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    Low surface brightness (LSB) galaxies have very diffuse, low surface density stellar discs that appear faint in optical images. They are very rich in neutral hydrogen (H I) gas, which extends well beyond the stellar discs. ...
  • p-mode interaction with sunspots 
    Cally, P. S; Moradi, H; Rajaguru, S. P (John-Wiley and Sons, 2016)
    This chapter brings together two of the prominent features of our star the Sun: its well‐developed p‐mode spectrum of global oscillations excited by near‐surface convection, and its magnetic activity famously represented ...
  • UV astronomy and stellar chromosphere 
    Kameswara Rao, N (Saha Institute of Nuclear Physics, 1995)
    "The abrupt termination of solar and stellar spectrum below A 2900 has been a great handicap to the advancement of our knowledge of the heavenly bodies ; because the ...
  • Cosmic relics from the microsecond epoch 
    Bhattacharjee, P (Saha Institute of Nuclear Physics, 1995)
    "A phase transition from quark-gluon plasma to hadronic matter may have ocurred in the early universe when the universe was about 10 ~sec old and the temperature was about 100-200 MeV. Is there any relic from that microsecond ...
  • Sunspot area catalog revisited: Daily cross-calibrated areas since 1874 
    Mandal, Sudip; Krivova, N. A; Solanki, S. K; Sinha, N; Banerjee, D (EDP Sciences, 2020-08)
    Context. Long and consistent sunspot area records are important for understanding long-term solar activity and variability. Multiple observatories around the globe have regularly recorded sunspot areas, but such individual ...
  • Validation of estimated cloud fraction from MERRA-2 and AIRS data using ground based observation over IAO, Hanle 
    Shantikumar, S. N; Narendra, A; Bhatt, B. C; Prabhu, T. P; Anupama, G. C; Angchuk, D; Jorphail, S (Elsevier B.V, 2020-08-15)
    We report for validation of cloud fraction estimated from high-resolution (hourly) data from MERRA-2 and AIRS instrument aboard NASA’s Aqua satellite during its ascending and descending orbits with hourly ground-based ...
  • Asymmetry in the length scales of the solar supergranulation network 
    Raju, K. P (IOP Publishing, 2020-08-20)
    Supergranulation is the horizontal velocity pattern on the solar surface with a typical size of 30,000 km and a lifetime of 24 hr. The network structure seen in chromospheric lines, such as Ca ii K 3934 Å, is the manifestation ...

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