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Browsing by Author "Mathew, B"

Browsing by Author "Mathew, B"

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  • Determination of the size of the dust torus in H0507+164 through optical and infrared monitoring 
    Amit Kumar; Rakshit, S; Kshama, S. K; Stalin, C. S; Mathew, B; Hoenig, Sebastian; Gandhi, Poshak; Sagar, R; Pandge, M. B (Oxford University Press on behalf of the Royal Astronomical Society, 2018-04)
    The time delay between flux variations in different wavelength bands can be used to probe the inner regions of active galactic nuclei (AGNs). Here, we present the first measurements of the time delay between optical and ...
  • Discovery of an M-type companion to the Herbig Ae Star V1787 Ori 
    Arun, R; Mathew, B; Sridharan, R; Manoj, P; Narang, M; Kartha, S. S; Maheswar, G (Oxford University Press on behalf of the Royal Astronomical Society, 2021-02)
    The intermediate-mass Herbig Ae star V1787 Ori is a member of the L1641 star-forming region in the Orion A molecular cloud. We report the detection of an M-type companion to V1787 Ori at a projected separation of 6.66 arcsec ...
  • Disentangling the two sub-populations of early Herbig Be stars using VLT/X-shooter spectra 
    Shridharan, B; Mathew, B; Arun, R; Cysil, T. B; Subramaniam, A; Manoj, P; Maheswar, G; Sudheesh, T. P (EDP Sciences, 2023-11)
    Early Herbig Be (HBe) stars are massive, young stars accreting through the boundary layer mechanism. However, given the rapid (<2 Myr) evolution of early Herbig stars to the main-sequence phase, studying the evolution of ...
  • 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 ...
  • Emission line star catalogues post-Gaia DR3: A validation of Gaia DR3 data using the LAMOST OBA emission catalogue 
    Shridharan, B; Mathew, B; Bhattacharyya, S; Robin, T; Arun, R; Kartha, S. S; Manoj, P; Nidhi, S; Maheswar, G; Paul, K. T; Narang, M; Himanshu, T (EDP Sciences, 2022-12)
    Aims. Gaia Data Release 3 (DR3) and further releases have the potential to identify and categorise new emission-line stars in the Galaxy. We perform a comprehensive validation of astrophysical parameters from Gaia DR3 ...
  • Estimation of the size and structure of the broad line region using Bayesian approach 
    Mandal, A. K; Rakshit, S; Stalin, C. S; Petrov, R. G; Mathew, B; Sagar, R (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    Understanding the geometry and kinematics of the broad line region (BLR) of active galactic nuclei (AGN) is important to estimate black hole masses in AGN and study the accretion process. The technique of reverberation ...
  • NGC 7419: a young open cluster with a number of very young intermediate mass pre-MS stars 
    Subramaniam, A; Mathew, B; Bhatt, B. C; Ramya, S (Blackwell Publishing, 2006-06)
    We present a photometric and spectroscopic study of the young open cluster NGC 7419, which is known to host a large number of classical Be stars for reasons not well understood. Based on CCD photometric observations of 327 ...
  • NIR properties of Be stars in star clusters in the Magellanic Clouds 
    Paul, K. T; Subramaniam, A; Mathew, B; Shruthi, S. B (Elsevier B.V, 2017-10)
    Magellanic Clouds are the nearby galaxies which are ideal to study the properties of metal poor stellar population. In this study, we explore the near-IR properties of optically identified classical Be stars in 19 star ...
  • Optical and near-infrared photometric study of the open cluster NGC 637 and 957 
    Yadav, R. K. S; Kumar, B; Subramaniam, A; Sagar, R; Mathew, B (Royal Astronomical Society, 2008-11)
    We present UBVRI CCD photometry in the region of the open clusters NGC 637 and 957. The radii are found to be 4.2 and 4.3 arcmin. Their reddenings E(B - V) are 0.64 +/- 0.05 and 0.71 +/- 0.05 mag and their distances, from ...
  • Optical spectroscopy of classical Be stars in open clusters 
    Mathew, B; Subramaniam, A (Astronomical Society of India, 2011-12)
    We present a spectroscopic study of 150 Classical Be stars in 39 open clusters using medium resolution spectra in the wavelength range 3800 – 9000 A° . Onethird of the sample (48 stars in 18 clusters) has been studied ...
  • 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 ...
  • Optical/IR studies of Be stars in NGC 6834 with emphasis on two specific stars 
    Mathew, B; Varricatt, W. P; Subramaniam, A; Ashok, N. M; Banerjee, D. P. K (IOP Publishing, 2014-09)
  • Photometric and spectroscopic study of candidate Be stars in the Magellanic Clouds 
    Paul, K. T; Subramaniam, A; Mathew, B; Mennickent, R. E; Sabogal, B (Cambridge University Press, 2011-07)
    Mennickent et al. (2002) presented a catalogue of 1056 Be star candidates in the Small Magellanic cloud (SMC) by studying light curve variation using OGLE II data base. They classified these Be star candidates of the SMC ...
  • Pre-main sequence stars, emission stars and recent star formation in the Cygnus region 
    Bhavya, B; Mathew, B; Subramaniam, A (Astronomical Society of India, 2007-09)
    The recent star formation history in the Cygnus region is studied using 5 clusters (IC 4996, NGC 6910, Berkeley 87, Biurakan 2 and Berkeley 86). The optical data from the literature are combined with the 2MASS data to ...
  • Quasar catalogue for the astrometric calibration of the forthcoming ILMT survey 
    Mandal, A. K; Pradhan, Bikram; Surdej, Jean; Stalin, C. S; Sagar, R; Mathew, B (Indian Academy of Sciences, 2020-12)
    Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will ...
  • Spectroscopic study of a few Herbig Ae/Be stars in young open clusters 
    Mathew, B; Subramaniam, A; Bhavya, B (Astronomical Society of India, 2010-03)
    In this article we give an overview of the developments in the field of spectral classification and its continued importance in the fields of stellar and galactic evolution. The extension of MK system to cool stars as well ...
  • Spectroscopic study of Be-shell stars : 4 Her and 88 Her 
    Bhat, S. S; Paul, K. T; Subramaniam, A; Mathew, B (IOP Publishing, 2016-06)
    We present an optical spectroscopic study based on 41 spectr a of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotationa l velocity of these stars from He I lines in the blue ...
  • Spectroscopic survey of emission line stars in open clusters 
    Subramaniam, A; Mathew, B (Springer, 2010)
    We summarize a study of emission-line stars in young open clusters. The study was done in two phases. The first phase was the survey, where the emission stars in young open clusters were identified using the slitless ...
  • Spectroscopy of Be stars in young open clusters 
    Mathew, B; Subramaniam, A (Astronomical Society of India, 2010)
    A spectroscopic study of 152 Classical Be stars in 42 young open clusters was performed using medium resolution spectra in 3700-9000 A range, to understand the Be phenomenon. The Balmer decrement is found to have a ...
  • Star formation around three co-moving HAeBe stars in the Cepheus Flare 
    Saha, Piyali; Maheswar, G; Mathew, B; Kamath, U. S (EDP Sciences, 2021-09)
    The presence of three more Herbig Ae/Be (HAeBe) candidates in the Cepheus Flare within a 1.5° radius centered on HD 200775 suggests that star formation is prevalent in a wider region of the LDN 1147/1158, LDN 1172/1174, ...

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