AR_final file_2018-19

Priya Hasan Spectroscopic study of NGC 281 West NGC 281 is a complex region of star formation at 2.8 kpc, and is situated 300 pc above the Galactic plane, and appears to be part of a 270 pc diame- ter ring of atomic and molecular clouds expand- ing at 22 km/s (Megeath, et al. 2003). It ap- pears that two modes of triggered star formation are at work here: an initial supernova to trigger the ring complex and the initial O stars and the subsequent triggering of low mass star formation by photo evaporation driven molecular core com- pression. To get a complete census of the young stellar population, we use Chandra ACIS 100 ksec coupled with data from 2MASS and Spitzer. The Master X-ray catalog has 446 sources detected in different bandpasses. We present the spatial distri- bution of Class I, II and III sources to study the progress of star formation. We also determine the gas to dust ratio N H /A K to be 1.93 ± 0.47 × 10 22 cm − 2 mag − 1 for this region. In this study, we present NGC 281 as a good target to study with the 3.6m Devasthal Optical Telescope (DOT) in spec- troscopy. With these spectra, we look for evidence for the pre-main-sequence (PMS) nature of the ob- jects, study the properties of the detected emission lines as a function of evolutionary class, and ob- tain spectral types for the observed young stellar objects (YSOs). The temperatures implied by the spectral types can be combined with luminosities determined from the near-infrared (NIR) photom- etry to construct Hertzsprung–Russell (HR) dia- grams for the clusters. By comparing the posi- tions of the YSOs in the HR diagrams with the PMS tracks, we can determine the ages of the em- bedded sources and study the relative ages of the YSOs with and without optically thick circumstel- lar disks. A photometric study of the non-relaxed cluster Mayer 3 The astrophysical parameters of the open star clus- ter Mayer 3 have been estimated using observa- tions at the Newtonian focus (f/4.84) of the 1.88 m telescope at Kottamia Observatory in Egypt. The V RI observations have been carried out down to a limiting magnitude of V ∼ 20 mag. To deter- mine membership and estimate the astrophysical parameters, V RI , near-infrared Two Micron All Sky Survey (2MASS) and Gaia DR2 data have been used. The core and tidal radii, radial density distri- bution, colour-magnitude diagrams, distance, age, and reddening of Mayer 3 are presented. The lu- minosity and mass functions, and the total mass of the cluster are estimated. Finally, we conclude that Mayer 3 is not dynamically relaxed as the re- laxation time estimated is much larger than the clusters age. This work has been done in collabo- ration with A. L. Tadrass, and R. Bendary. S.N.A. Jaaffrey Study of x-ray emission characteristics in solar flares employing SOXS: CZT detector Our project involves a unique sample of 11 solar flare events observed by the space mission Solar X-ray Spectrometer (SOXS), particularly by CZT detector. We study temporal characteristics of 11 flares in general and rise time characteristics in par- ticular. For this purpose, we got an opportunity to learn newly developed software in IDL. The flares selection is based on the GOES intensity in the range of M1.0-X1.0. The catalogue of all the flares chosen for this work is presented in table. The rise time of flares vary between 123 and 433 secs in 4 . 0 = 5 . 5 keV energy band while shortest rise time of the order of ∼ 60 secs has been observed in 20-56 keV high energy bands. Our results reveal unique feature that rise time decays exponentially towards high energy. This result suggests that short rise time at high energy tail may be due to faster ac- celeration of electrons and thereby producing non- thermal bremesstrahlung via collisions of electrons with ambient plasma in solar flare loops. This work has been done in collaboration with Umang Pandya, and Rajmal Jain. QPO detection in superluminal black hole GRS 1915+105 We report on the first superluminal black hole GRS 1915+105 observed by the Rossi X-ray Timing Ex- plorer - Proportion Counter Array (RXTE/PCA). We detect the Quasi Periodic Oscillations (QPOs) in the Power Density Spectrum (PDS) of source, which have luminosity very near to Eddington limit and long variability in X-ray light curve. In power density spectrum, we deal with the study of highly variability amplitude, time evolution of the char- acteristic timescale, quality factor, and full width at half maximum (FWHM). We find significant ( 193 )