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Browsing IIAP Publications by Subject "Circumstellar matter"

Browsing IIAP Publications by Subject "Circumstellar matter"

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  • Are C60 Molecules Detectable in Circumstellar Shells of R Coronae Borealis Stars? 
    García-Hernández, D. A; Kameswara Rao, N; Lambert, D. L (IOP Publishing, 2011-03-10)
    The hydrogen-poor, helium-rich, and carbon-rich character of the gas around R Coronae Borealis (RCB) stars has been suggested to be a site for formation of C60 molecules. This suggestion is not supported by observations ...
  • Binarity and Accretion in AGB Stars: HST/STIS Observations of UV Flickering in Y Gem 
    Sahai, R; Contreras, C. S; Mangan, A. S; Sanz-Forcada, J; Muthumariappan, C; Claussen, M. J (IOP Publishing, 2018-06-20)
    Binarity is believed to dramatically affect the history and geometry of mass loss in AGB and post-AGB stars, but observational evidence of binarity is sorely lacking. As part of a project to search for hot binary companions ...
  • Chemical composition of a sample of candidate post-asymptotic giant branch stars 
    Sumangala Rao, S; Giridhar, S; Lambert, D. L (Wiley-Blackwell, 2012-01)
    We have derived elemental abundances for a sample of nine IRAS sources with colours similar to those of post-asymptotic giant branch (post-AGB) stars. For IRAS 01259+6823, IRAS 05208−2035, IRAS 04535+3747 and IRAS 08187−1905, ...
  • The chemical composition of the post-asymptotic giant branch F supergiant CRL 2688 
    Ishigaki, M. N; Parthasarathy, M; Reddy, B. E; García-Lario, P; Takeda, Y; Aoki, W; García-Hernández, D. A; Manchado, A (Wiley-Blackwell, 2012-09)
    We present an analysis of a high-resolution (R ∼ 50 000) optical spectrum of the central region of the protoplanetary nebula CRL 2688. This object is thought to have recently moved off the asymptotic giant branch (AGB) and ...
  • The Curious Case of PDS 11: A Nearby, >10 Myr Old, Classical T Tauri Binary System 
    Mathew, B; Manoj, P; Bhatt, B. C; Sahu, D. K; Maheswar, G; Muneer, S (IOP Publishing, 2017-05)
    We present results of our study of the PDS 11 binary system, which belongs to a rare class of isolated, high Galactic latitude T Tauri stars. Our spectroscopic analysis reveals that PDS 11 is an M2–M2 binary system with ...
  • Dust around R Coronae Borealis Stars. I. Spitzer/Infrared Spectrograph Observations 
    Aníbal García-Hernández, D; Kameswara Rao, N; Lambert, D. L (IOP Publishing, 2011-09-20)
    Spitzer/infrared spectrograph (IRS) spectra from 5 to 37 μm for a complete sample of 31 R Coronae Borealis stars (RCBs) are presented. These spectra are combined with optical and near-infrared photometry of each RCB at ...
  • Dust Around R Coronae Borealis Stars. II. Infrared Emission Features in an H-poor Environment 
    Garcia-Hernandez, D. A; Kameswara Rao, N; Lambert, D. L (IOP Publishing, 2013-08-20)
    Residual Spitzer/Infrared Spectrograph spectra for a sample of 31 R Coronae Borealis (RCB) stars are presented and discussed in terms of narrow emission features superimposed on the quasi-blackbody continuous infrared ...
  • Evolution of emission line activity in intermediate mass young stars 
    Manoj, P; Bhatt, H. C; Maheswar, G; Muneer, S (American Astronomical Society, 2006-12-10)
    We present optical spectra of 45 intermediate-mass Herbig Ae/Be stars. Together with the multiepoch spectroscopic and photometric data compiled for a large sample of these stars and ages estimated for individual stars by ...
  • An excess of mid-infrared emission from the type Iax SN 2014dt 
    Fox, O. D; Johansson, J; Kasliwal, M; Andrews, J; Bally, J; Bond, H. E; Boyer, M. L; Gehrz, R. D; Helou, G; Hsiao, E. Y; Masci, F. J; Parthasarathy, M; Smith, N; Tinyanont, S; Van Dyk, S. D (IOP Publishing, 2016-01)
    Supernovae Type Iax ( SNe Iax ) are less energetic and less luminous than typical thermonuclear explosions. A suggested explanation for the observed characteristics of this subclass is a binary progenitor system ...
  • Excitation Mechanism of O i Lines in Herbig Ae/Be Stars 
    Mathew, v; Manoj, P; Narang, Mayank; Banerjee, D. P. K; Pratheeksha Nayak; Muneer, S; Vig, S; Kumar, S. P; Paul, K. T; Maheswar, G (IOP Publishing, 2018-04-10)
    We have investigated the role of a few prominent excitation mechanisms viz. collisional excitation, recombination, continuum fluorescence, and Lyman beta fluorescence on the O i line spectra in Herbig Ae/Be stars. The aim ...
  • Far-infrared study of K giants in the solar neighborhood: connection between Li enrichment and mass-loss 
    Bharat Kumar, Y; Reddy, B. E; Muthumariappan, C; Zhao, G (EDP Sciences, 2015-05)
    Context. A small group of red giant branch (RGB) stars are known to have anomalous Li enhancement whose origin is still not well understood. Some studies have proposed that the Li enhancement in RGB stars is correlated to ...
  • First detection of a magnetic field in low-luminosity B[e] stars New scenarios for the nature and evolutionary stages of FS CMa stars 
    Korcakova, D; Sestito, F; Manset, N; Kroupa, P; Votruba, V; Slechta, M; Danford, S; Dvorakova, N; Raj, A; Chojnowski, S. D; Singh, H. P (EDP Sciences, 2022-03)
    We report the first detection of the magnetic field in a star of FS CMa type, a subgroup of objects characterized by the B[e] phenomenon. The split of magnetically sensitive lines in IRAS 17449+2320 determines the magnetic ...
  • First evidence of the possible detection of diffuse circumstellar bands in AGB descendants 
    Di­az-Luis, J. J; Garcia-Hernandez, D. A; Kameswara Rao, N; Manchado, A; Cataldo, F (Societa Astronomica Italiana, 2016-06)
    The short transition phase between asymptotic giant branch stars (AGB; when circumstellar envelopes rich in small organic molecules are efficiently created) and planetary nebulae (PNe) represents a most active phase of ...
  • High-resolution Optical Spectroscopy of DY Cen: Diffuse Interstellar Bands in a Proto-fullerene Circumstellar Environment? 
    Garcia-Hernandez, D. A; Kameswara Rao, N; Lambert, D. L (IOP Publishing, 2012-11-01)
    We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis star DY Cen for electronic transitions of the C60 molecule and diffuse interstellar bands (DIBs). We report the non-detection ...
  • High-resolution spectroscopy of the extremely iron-poor post-AGB star CCâLyr 
    Aoki, W; Matsuno, Tadafumi; Honda, S; Parthasarathy, M (Astronomical Society of Japan, 2017-04)
    High-resolution optical spectroscopy was conducted for the metal-poor post-AGB star CC Lyr to determine its chemical abundances and spectral line profiles. Our standard abundance analysis confirms its extremely low ...
  • Mid-infrared variations of R Coronae Borealis stars 
    Kameswara Rao, N; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2015-03-11)
    Mid-infrared (IR) photometry of R Coronae Borealis stars obtained from various satellites from Infrared Astronomical Satellite (IRAS) to Wide-field Infrared Survey Explorer (WISE) has been utilized in studying the ...
  • Models of highly extended dust shells around R Coronae Borealis 
    Nagendra, K. N; Leung, C. M (Royal Astronomical Society, 1996-08)
    Radiation transport models are constructed for the dust shells of the hydrogen deficient supergiant star R Coronae Borealis (R CrB). IRAS observations of R CrB are used as constraints in selecting the model parameters. ...
  • The Nebular Remnant and Quiescent Spectrum of Nova Gk-Persei 
    Anupama, G. C; Prabhu, T. P (Royal Astronomical Society, 1993-07-15)
    CCD images of the nebular shell of the old nova GK Per in [N II] and [O III] emission lines, and also the quiescent spectrum in the optical region, are presented. Proper motion measurements of the knots in [N II]over the ...
  • Optical Emission Bands in the Spectrum of the R-Coronae and V854-CENTAURI at Minimum 
    Kameswara Rao, N; Lambert, D. L (Royal Astronomical Society, 1993-08-01)
    Several unidentified broad emission features, previously seen only in the spectrum of the nebulosity in the Red Rectangle, have been observed in a spectrum of the R CrB star V854 Cen taken in a deep minimum. Similarities ...
  • Physical parameters and long-term photometric variability of V1481 Ori, an SB2 member of Orion nebula Cluster with an accreting component 
    Messina, S; Parihar, P. S; Biazzo, K; Lanza, A. F; Distefano, E; Melo, C. H. F; Bradstreet, D. H; Herbst, W (Oxford University Press on behalf of the Royal Astronomical Society, 2016-04)
    We present the results of our analysis on V1481 Ori (JW 239), a young SB2 in the Orion nebula Cluster with a circumbinary disc accreting on the lower mass component. The analysis is based on high-resolution spectroscopic ...

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