2010 (IPP)
Permanent URI for this collectionhttp://localhost:4000/handle/11007/152
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Item Interstellar dust models towards some IUE stars(2010-11-24) Katyal, Nisha; Gupta, Ranjan; Vaidya, D.B.We present a study of interstellar extinction towards certain directions in our galaxy defined by about 59 stars which were observed by the IUE satellite. The observed UV extinction curves have been modeled by making light scattering calculations based on Discrete Dipole Approximation (DDA) for extinction efficiencies of composite dust grains which is made up of a host silicate spheroid and graphite inclusions. The study indicates that smaller dust grains are more efficient for the directions in the galaxy where observed Rv values are found to be low.Item Optical spectroscopy of candidates of young stellar objects in NGC 1333(2010-12-31) Itoh, Yoichi; et al.; Gupta, Ranjan; Oasa, YumikoWe carried out low-resolution optical spectroscopy of 14 low-luminosity young stellar object (YSO) candidates in the NGC 1333 cluster. These objects were previously identified by the near-infrared imaging survey. Eleven objects were confirmed as YSOs by the H line emission. Strengths of the H emission are correlated with the near-infrared excesses of the objects. Spectral types of all YSOs are estimated to be M-type, indicative of low-mass. Comparisons of the results of our spectroscopic observations and the previous photometric observations with evolutionary tracks on the HR diagram suggest two objects to be young brown dwarfs.