|Abstract : || |
Episodic accretion in Young Stellar Objects (YSOs) is the sudden enhancement of the accretion rate from the circumstellar disc onto the central pre-main sequence (PMS) star. The phenomena of episodic accretion first came into light in the year 1936 when a star, FU Orionis, of the B35 dark nebula present in the Orion star-forming region, suddenly brightened more than 5 magnitudes from its historical magnitude of ∼ 16 magnitudes (Wachmann, 1954). G. H. Herbig (1966) proposed that this phenomenon of “outburst” represent an important stage of low mass star formation. In the following decades, more such objects undergoing “outbursts” were discovered. The sources so discovered exhibited a variety of outburst amplitudes and outburst durations. Therefore, based on their outburst duration and amplitudes, the sources were classified into two categories: FUors (resembling FU Orionis type outburst) and EXors (resembling EX Lupi type outburst which is the first progeny of this type of source). Episodic accretion event also plays a significant role in the final evolution of the central PMS star and the planet formation. In this thesis, we performed a multi-wavelength
spectro-photometric study of two sources Gaia 20eae and V2493 Cyg to further our understanding of this phenomena. The contributions and important findings of this thesis work along with future prospects will be discussed in this talk. In addition to this, I will also present the calibration results of two NIR instruments of DOT: TIRCAM2 and TANSPEC which I have performed as a part of this thesis.