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Runaway O and Be stars found using Gaia DR3, new stellar bow shocks and search for binaries
Paredes, J. M.; Ribó, M.; Benaglia, P. +1 more
A relevant fraction of massive stars are runaways, moving with a significant peculiar velocity with respect to their environment. Kicks from supernova explosions or the dynamical ejection of stars from clusters can account for the runaway genesis. We have used Gaia DR3 data to study the velocity distribution of massive O and Be stars from the GOSC…
X-ray Observations of the Intermediate Polar TX Col
Joshi, Arti; Rawat, Nikita; Rao, Srinivas M. +2 more
We present the timing analysis of the intermediate polar TX Col in the X-ray band using the observations made by Chandra, Swift, and Suzaku during the years 2000, 2007, and 2009, respectively. The spin, orbital, and beat periods derived from these data are consistent with the earlier findings. We found that the spin modulation was dominant during …
Star Formation Characteristics of Galaxies Hosting AGN
Nandi, Payel; Subramonian Stalin, Chelliah
We present an analysis of the ultra-violet (UV) observations of two Seyfert type active galactic nuclei (AGN), namely NGC 4051 and NGC 4151. These observations aimed at studying the star formation in the hosts of these AGN were carried out with the ultra-violet imaging telescope on board AstroSat in far-UV. A total of 193 and 328 star-forming regi…
Observational Characteristics of Solar EUV Waves
Joshi, Bhuwan; Chen, P. F.; Awasthi, Arun Kumar +4 more
Extreme-ultraviolet (EUV) waves are one of the large-scale phenomena on the Sun. They are defined as large propagating fronts in the low corona with speeds ranging from a few tens km s‑1 to several 1000 km s‑1. They are often associated with solar filament eruptions, flares, and/or coronal mass ejections (CMEs). EUV waves exhibit various features,…
AstroSat Investigation of X-ray Flares on Two Active K-M Systems: CC Eri and AB Dor
Karmakar, Subhajeet; Rawat, Nikita; Pandey, Jeewan Chandra +2 more
We present an X-ray and UV investigation of five X-ray flares detected on two active systems, CC Eri and AB Dor, using the AstroSat observatory. The peak X-ray luminosities of the flares in the 0.3–7.0 keV band are found to be within 1031‑33 erg s‑1. Preliminary spectral analysis indicates the presence of three and four-temperature corona for CC E…
Coronal Modulation in the Ultra-fast Rotator LO Peg
Pandey, Jeewan Chandra; Singh, Gurpreet; Yadava, Umesh
We present coronal imaging of the ultra-fast rotator, LO Peg, using the X-ray observations from XMM-Newton. The X-ray light curves show one strong flare at the end of observation, as reported in an earlier study. On removal of flaring events, the quiescent state light curve shows rotational modulations, which are modelled using a maximum likelihoo…
Caught in flagrante delicto: Evidence for past mass transfer in massive binaries?
Rauw, G.
Many massive binary systems undergo mass and angular momentum transfer over the course of their evolution. This kind of interaction is expected to deeply affect the properties of the mass donor and mass gainer and to leave various observational signatures. The most common smoking guns of a past mass transfer episode are notably rapid rotation of t…
X-raying the wind-wind collisions in HD 168112 and HD 167971
Blomme, R.; Nazé, Y.; Rauw, G. +1 more
The O-type long-period binary HD 168112 and triple HD 167971 star systems have been known for several decades for their non-thermal synchrotron radio emission. This emission arises from relativistic electrons accelerated in the hydrodynamic shocks of the wind collisions in these systems. Such wind collisions are expected to produce a strong X-ray …
Influence of Mid-infrared Galactic Bubble on Surroundings: A Case Study on IRAS 16489-4431
Liu, Tie; Wang, Ke; Dewangan, Lokesh +3 more
We studied the influence of a massive star on a mid-infrared bubble and its surrounding gas in the IRAS 16489-4431 star-forming region using multi-wavelength data. The Spitzer mid-infrared band images revealed the shocked nature of the bubble. Analyses showed that the bubble is developed by a massive star owing to its strong radiation pressure. Ev…
Study of Wolf-Rayet Stars Using uGMRT
Tej, Anandmayee; del Palacio, Santiago; Saha, Anindya +4 more
In recent years, systems involving massive stars with large wind kinetic power have been considered as promising sites for investigating relativistic particle acceleration in low radio frequencies. With this aim, we observed two Wolf-Rayet systems, WR 114 and WR 142, using upgraded Giant Meterwave Radio Telescope observations in Band 4 (550–950 MH…