Abstract Details
| Name: Supriyo Ghosh Affiliation: S. N. Bose National Centre for Basic Sciences Conference ID: ASI2015_568 Title : Phase dependent spectro-photometric studies of a new Mira variable MASTER Optical Transient J212444.87+321738.3 Authors and Co-Authors : Supriyo Ghosh$^1$, Soumen Mondal$^1$, Ramkrishna Das$^1$, N. M. Ashok$^2$, D. P. K. Banerjee$^2$, \& Somnath Dutta$^1$ \\ $^1$S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata-700 098 \\ $^2$Physical Research Laboratory, Navrangpura, Ahmedabad-380 009 \\ Abstract Type : Oral Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : We present here optical/near-IR photometric and spectroscopic observations of the MASTER bright optical transient J212444.87+321738.3 using the Near-IR Imager cum spectrograph(NICMOS-3) on the 1.2-m IR telescope at Mt. Abu, and HFOSC and TIRSPEC on 2m Himalayan Chandra Telescope (HCT) at Hanle. The optical/near-IR spectra shows molecular features of TiO,VO, CO overtone and water bands, which is a signature of cool M-type stars. The NIR spectra indicates the likely O-rich nature as the $C_2$ bandhead at 1.77 $\mu$m is absent and it shows the likely presence of Si I absorption at 1.59 $\mu$m. The large (J-K) colour index of about 2.0 mag suggests that the source might be a late M-type star. The source was monitored in optical I-band using 40 cm telescope at Chile through International collaboration over 550 days, and shows the period of about 512 days with variability amplitude of about 4 mag in I-band. The luminosity class is confirmed from spectral data fitting using Phoenix theoretical models, which match well only with surface gravities of giants. These observations confirm that the source is a O-rich Mira variable. We also study the phase-dependent optical/Near-IR spectral variability of the source, which shows significant variable molecular features (e.g. VO, TiO, H$_2$O and CO bands) like commonly observed in Miras over phase. In this poster, we shall discuss the spectro-photometric observations of this new Mira object and it's fundamental parameters. |