Abstract Details

Name: Akshaya Subbanna M S
Affiliation: Christ University
Conference ID: ASI2017_440
Title : Modelling the Diffuse Ultraviolet Radiation towards Galactic Cirrus Cloud G251.2+73.3
Authors and Co-Authors : Akshaya Subbanna M S (Christ University, Bangalore), Ravichandran S (Christ University, Bangalore), Jayant Murthy (Indian Institute of Astrophysics, Bangalore)
Abstract Type : Poster
Abstract Category : Stars,ISM and the Galaxy
Abstract : The Galactic cirrus cloud G251.2+73.3 in the north galactic pole which showed excess emission in the ultraviolet (UV) region is studied in the UV and the infrared (IR) bands using data from Galaxy Evolution Explorer for the UV band (far-UV and near-UV) and Infrared Astronomy Satellite (60μm and 100μm) and Planck (350μm and 550μm) for the IR band. Good correlation was found between the UV and IR bands indicating that the emission is mainly due to the starlight scattered by interstellar dust grains. The correlation between the FUV/NUV ratio and the FUV intensity shows that there is excess emission seen in the FUV which is absent in the NUV. This excess emission was found to be due to the fluorescent molecular hydrogen emission from G251.2+73.3 and a molecular cloud GAL 249.00+73.70 present close to the cirrus cloud. We have tried to model the diffuse UV emission in this direction of the sky using the three dimensional extinction map given by Green et al. and a Monte Carlo modelling approach. The model data was found to fit well with the observed data with an offset of about 300 photons per (cm^2 s sr Å) (PU) in the FUV and about 570PU in the NUV. The best fitting albedo was 0.6 and 0.2 in the FUV and NUV respectively while the best fit for the phase function asymmetry factor was found to be 0.7 and 0.2. From the models it was also found that the scattered flux depended more on the value of phase function asymmetry factor than on the albedo of the grains in this region.