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Browsing by Author "Sengupta, S"

Browsing by Author "Sengupta, S"

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  • Charged particle trajectories in a toroidal magnetic and rotation-induced electric field around a black hole 
    Sengupta, S (World Scientific Publishing Company, 1997-10)
    Trajectories of charged particles in a combined poloidal, toroidal magnetic field and a rotation-induced unipolar electric field superposed on a Schwarzschild background geometry have been investigated extensively in the ...
  • Charged particle trajectories in the presence of a toroidal magnetic field on a Schwarzschild background 
    Prasanna, A. R; Sengupta, S (Elsevier, 1994-09)
    Trajectories of a single charged particle in the presence of toroidal magnetic fields superposed on the Schwarzschild background geometry have been obtained, and it is shown that the toroidal field repels the particles and ...
  • Cloudy atmosphere of the extra-solar planet HD189733b: A possible explanation of the detected B-band polarization 
    Sengupta, S (IOP Science, 2008-08)
    The peak amplitude of linear polarization detected recently from an extraso- lar hot giant planet HD 189733b, is a few times of 10−4 , more than an order of magnitude higher than all theoretical predictions. Rayleigh ...
  • A Comprehensive Model of Morphologically Realistic Cosmic Dust Particles: An Application to Mimic the Unusual Polarization Properties of the Interstellar Comet 2I/Borisov 
    Halder, Prithish; Sengupta, S (American Astronomical Society, 2023-04-10)
    The cosmic dust particles found in space are mainly porous aggregates of smaller grains. Theoretically, these aggregates are replicated using fractal geometry, assuming a cluster of spheres. Although the light ...
  • Constraints on cosmic electric charge asymmetry and neutrino charge from the microwave background 
    Sengupta, S; Pal, B. P (Elsevier B.V, 1996-01)
    We point out that an overall electric charge asymmetry in the universe will generate an anisotropy in the cosmic microwave background radiation (CMBR) via the Sach-Wolfe effect. From this, an upper limit on the electric ...
  • Critical Analysis of Tess Transit Photometric Data: Improved Physical Properties for Five Exoplanets 
    Saha, Suman; Sengupta, S (2021-11-01)
    We present improved physical parameters for four hot Jupiters: KELT-7 b, HAT-P-14 b, WASP-29 b, WASP-95 b, and a hot Neptune: WASP-156 b, by performing critical and rigorous analysis of the time-series observations from the ...
  • Detecting exomoons around self-luminous giant exoplanets through polarization 
    Sengupta, S; Marley, M. S (IOP Publishing, 2016-06-20)
    Many of the directly imaged self-luminous gas-giant exoplanets have been found to have cloudy atmospheres. Scattering of the emergent thermal radiation from these planets by the dust grains in their atmospheres should ...
  • Detection of Polarization due to Cloud Bands in the Nearby Luhman 16 Brown Dwarf Binary 
    Millar-Blanchaer, M. A; Girard, J. H; Karalidi, T; Marley, M. S; van Holstein, R. G; Sengupta, S; Mawet, Dimitri; Kataria, Tiffany; Jos de Boer, F. S (IOP Publishing, 2020-05-01)
    Brown dwarfs exhibit patchy or spatially varying banded cloud structures that are inferred through photometric and spectroscopic variability modeling techniques. However, these methods are insensitive to rotationally ...
  • The development of HISPEC for Keck and MODHIS for TMT: science cases and predicted sensitivities 
    Konopacky, Quinn M; Baker, Ashley D; Mawet, Dimitri; Fitzgerald, Michael P; Jovanovic, Nemanja; Beichman, Charles; Ruane, Garreth; Bertz, Rob; Terada, Hiroshi; Dekany, Richard; Lingvay, Larry; Kassis, Marc; Anderson, David; Tamura, Motohide; Benneke, Bjorn; Beatty, Thomas; Do, Tuan; Nishiyama, Shogo; Plavchan, Peter; Wang, Jason; Wang, Ji; Burgasser, Adam; Ruffio, Jean-Baptiste; Zhang, Huihao; Brown, Aaron; Fucik, Jason; Gibbs, Aidan; Gibson, Rose; Halverson, Sam; Johnson, Christopher; Karkar, Sonia; Kotani, Takayuki; Kress, Evan; Leifer, Stephanie; Magnone, Kenneth; Maire, Jerome; Pahuja, Rishi; Porter, Michael; Roberts, Mitsuko; Sappey, Ben; Thorne, Jim; Wang, Eric; Artigau, Etienne; Blake, Geoffrey A; Canalizo, Gabriela; Chen, Guo; Doppmann, Greg; Doyon, Rene; Dressing, Courtney; Fang, Min; Greene, Thomas; Herczeg, Greg; Hillenbrand, Lynne; Howard, Andrew; Kane, Stephen; Kataria, Tiffany; Kempton, Eliza; Knutson, Heather; Lafrenière, David; Liu, Chao; Metchev, Stanimir; Millar-Blanchaer, Max; Narita, Norio; Pandey, G; Rajaguru, S. P; Robertson, Paul; Salyk, Colette; Sato, Bun’ei; Schlawin, Evertt; Sengupta, S; Sivarani, T; Skidmore, Warren; Vasisht, Gautam; Yasui, Chikako; Zhang, Hui (SPIE-The International Society for Optical Engineering, 2023-10)
    HISPEC is a new, high-resolution near-infrared spectrograph being designed for the W.M. Keck II telescope. By offering single-shot, R 100,000 spectroscopy between 0.98 – 2.5 µm, HISPEC will enable spectroscopy of transiting ...
  • Effect of Multiple Scattering on the Transmission Spectra and the Polarization Phase Curves for Earth-like Exoplanets 
    Singla, Manika; Chakrabarty, Aritra; Sengupta, S (American Astronomical Society, 2023-02-20)
    It is the most appropriate time to characterize the Earth-like exoplanets in order to detect biosignature beyond the Earth because such exoplanets will be the prime targets of big-budget missions like JWST, Roman ...
  • Effects of dust scattering in expanding spherical nebulae 
    Srinivasa Rao, M; Sengupta, S (Elsevier B. V., 2004-03)
    The mean intensity of planetary nebulae with an expanding atmosphere is modeled by considering dusty and dust-free atmospheres. The bulk matter density is determined from the adopted velocity field through the equation of ...
  • Effects of thermal emission on the transmission spectra of hot Jupiters 
    Chakrabarty, Aritra; Sengupta, S (IOP Publishing, 2020-07-20)
    The atmosphere on the dayside of a highly irradiated close-in gas giant (also known as a hot Jupiter) absorbs a significant part of the incident stellar radiation, which again gets re-emitted in the infrared wavelengths ...
  • Explaining the Observed Polarization from Brown Dwarfs by Single Dust Scattering 
    Sengupta, S (The American Astronomical Society, 2003-03)
    Recent observation of linear optical polarization from brown dwarfs confirms the dust hypothesis in the atmospheres of brown dwarfs with effective temperature higher than 1400 K. The observed polarization could arise because ...
  • General Relativistic Effects on the Induced Electric Field Exterior to Pulsars 
    Sengupta, S (The American Astronomical Society, 1995-08)
    The importance of general relativity to the induced electric field exterior to pulsars has been investigated by assuming aligned vacuum and nonvacuum magnetosphere models. For this purpose, the stationary and axisymmetric ...
  • General Relativistic Effects on the Ohmic Decay of Crustal Magnetic Fields in Neutron Stars 
    Sengupta, S (The American Astronomical Society, 1997-04)
    The ohmic decay of magnetic fields confined within the crust of neutron stars is considered by incorporating the effect of spacetime curvature produced by the intense gravitational field of the star. It is shown that the ...
  • Generic models for disk-resolved and disk-integrated phase-dependent linear polarization of light reflected from exoplanets 
    Chakrabarty, Aritra; Sengupta, S (IOP Publishing, 2021-08-20)
    Similar to the case of solar system planets, reflected starlight from exoplanets is expected to be polarized due to atmospheric scattering, and the net disk-integrated polarization should be nonzero owing to the asymmetrical ...
  • High-resolution Infrared Spectrograph for Exoplanet Characterization with the Keck and Thirty Meter Telescopes 
    Mawet, Dimitri; Fitzgerald, Michael; Konopacky, Quinn; Beichman, Charles; Jovanovic, Nemanja; Dekany, Richard; Hover, David; Chisholm, Eric; Ciardi, David; Artigau, Etienne; Banyal, Ravinder; Beatty, Thomas; Benneke, Bjorn; Blake, Geoffrey A; Burgasser, Adam; Canalizo, Gabriela; Chen, Guo; Do, Tuan; Doppmann, Greg; Doyon, Rene; Dressing, Courtney; Fang, Min; Greene, Thomas; Hillenbrand, Lynne; Howard, Andrew; Kane, Stephen; Kataria, Tiffany; Kempton, Eliza; Knutson, Heather; Kotani, Takayuki; Lafreniere, David; Liu, Chao; Nishiyama, Shogo; Pandey, G; Plavchan, Peter; Prato, Lisa; Rajaguru, S. P; Robertson, Paul; Salyk, Colette; Sato, Bun’ei; Schlawin, Everett; Sengupta, S; Sivarani, T; Skidmore, Warren; Tamura, Motohide; Terada, Hiroshi; Vasisht, Gautam; Wang, Ji; Zhang, Hui (American Astronomical Society, 2019-09)
    HISPEC (High-resolution Infrared Spectrograph for Exoplanet Characterization) is a proposed diffractionlimited spectrograph for the W.M. Keck Observatory, and a pathfinder for the MODHIS facility project (Multi-Object ...
  • Joule Heating in Neutron Stars under Strong Gravitation 
    Sengupta, S (The American Astronomical Society, 2000-11)
    Considering Joule heating caused by the dissipation of the magnetic field in the neutron star crust to be an efficient mechanism in maintaining a relatively high surface temperature in very old neutron stars, the role of ...
  • Line formation in the Atmosphere of brown dwarf Gliese 229B : CH_4 at 2.3 mu m 
    Sengupta, S; Krishan, V (European Southern Observatory, 2000-06)
    We investigate the formation of methane line at 2.3 μm in Brown Dwarf Gliese 229B. Two sets of model parameters with (a) T_eff=940 K and log (g) =5.0, (b) T_eff=1030 K and log (g)=5.5 are adopted both of which provide ...
  • Multiband transit follow-up observations of five hot Jupiters with critical noise treatments: improved physical properties 
    Saha, Suman; Chakrabarty, Aritra; Sengupta, S (IOP Publishing, 2021-07-01)
    The most challenging limitation in transit photometry arises from the noises in the photometric signal. In particular, the ground-based telescopes are heavily affected by the noise due to perturbation in the Earth’s ...

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