Related papers: A comprehensive statistical assessment of star-pla…
The dense, clustered environment in which massive stars form can lead to interactions with neighboring stars. It has been hypothesized that collisions and mergers may contribute to the growth of the most massive stars. In this paper we…
Using archival data from the Chandra X-ray telescope, we have measured the spatial extent of the hot interstellar gas in a sample of 49 nearby interacting galaxy pairs, mergers, and merger remnants. For systems with SFR > 1 M(sun)/yr, the…
X-ray observations of circumgalactic coronae provide a valuable means by which to test galaxy formation theories. Two primary mechanisms are thought to be responsible for the establishment of such coronae: accretion of intergalactic gas…
We study the relation between age and magnetic activity in late-type pre-main sequence (PMS) stars, for the first time using mass-stratified subsamples. The effort is based on the Chandra Orion Ultradeep Project (COUP) which provides very…
Understanding the relationship between close-in small planets (CS) and distant giants (DG) is central to understanding the formation of planetary systems like our own. Most studies of this connection have found evidence for a positive…
The Kepler light curves used to detect thousands of planetary candidates are susceptible to dilution due to blending with previously unknown nearby stars. With the automated laser adaptive optics instrument, Robo-AO, we have observed 620…
Although the study of X-ray binaries has led to major breakthroughs in high-energy astrophysics, their circumbinary environment at scales of $\sim$100--10,000 astronomical units has not been thoroughly investigated. In this paper, we…
Measuring the evolution of X-ray emission from pre-main sequence (PMS) stars gives insight into two issues: the response of magnetic dynamo processes to changes in interior structure and the effects of high-energy radiation on…
With the development of extreme high contrast ground-based adaptive optics instruments and space missions aimed at detecting and characterizing Jupiter- and terrestrial-mass planets, it is critical that each target star be thoroughly vetted…
The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, X-ray binaries and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected…
We present a systematic analysis on the X-ray variability in 13 bright quasars at z > 4.5, combining recent Swift observations from 2021 to 2023 and archival multi-epoch observations. Upper limits of the luminosity measurements were…
All cool stars show magnetic activity, and X-ray emission is the hallmark of this activity. Gaining an understanding of activity aids us in answering fundamental questions about stellar astrophysics and in determining the impact of activity…
Stars and their winds can contribute to the non-thermal (NT) emission in extragalactic jets. Given the complexity of jet-star interactions, the properties of the resulting emission are strongly linked to those of the emitting flows. We…
We analyzed the effects of having a close companion on the star formation activity of galaxies in 8K galaxy pair catalog selected from the 2dFGRS. We found that, statistically, galaxies with $r_{\rm p} < 25 {\rm h^{-1}}$ kpc and $\Delta V <…
We present a numerical Magnetohydrodynamic (MHD) study of the dependence of stellar mass and angular momentum- loss rates on the orbital distance to close-in giant planets. We find that the mass loss rate drops by a factor of…
In recent years a large number of Hot Jupiters orbiting in a very close orbit around the parent stars have been explored with the transit and doppler effect methods. Here in this work we study the gravitational microlensing effect of a…
We estimate the stellar parameters of late K and early M type Kepler target stars. We obtain medium resolution visible spectra of 382 stars with Kp-J>2 (~K5 and later spectral type). We determine luminosity class by comparing the strength…
Late-type stars interact with their close-in planets through their coronal magnetic fields. We introduce a theory for the interaction between the stellar and planetary fields focussing on the processes that release magnetic energy in the…
Continuous habitability of a planet is a critical condition for advanced forms of life to appear, but it can be endangered by astronomical events such as stellar encounters. The purpose of this study is to analyze close stellar encounters…
More than two dozen short-period Jupiter-mass gas giant planets have been discovered around nearby solar-type stars in recent years, several of which undergo transits, making them ideal for the detection and characterization of their…