Related papers: Staying star gamma Equ
The apparent regularity of the motion of the giant planets of our solar system suggested for decades that said planets formed onto orbits similar to the current ones and that nothing dramatic ever happened during their lifetime. The…
A weakly magnetized ($\sim 10^7$G) neutron star, slowly spun up by accretion in an X-ray binary, crosses the instability boundary for r-mode instability at P=1--2 msec. The amplitude of the oscillation, which initially increases only at the…
The overstability of the fundamental radial mode in M dwarf models was theoretically predicted by Rodr\'iguez-L\'opez et al. (2012). The periods were found to be in the ranges ~25-40 min and ~4-8 h, depending on stellar age and excitation…
We present the results of a systematic study of the magnetic fields and other properties of the Ap stars with resolved magnetically split lines. This study is based on new measurements of the mean magnetic field modulus, the mean…
We analyzed the host stars of the present sample of confirmed planets detected by Kepler and Kepler Objects of Interest (KOI) to compute new photometric rotation periods and to study the behavior of their angular momentum. Lomb-Scargle…
A majority part of magnetic chemically peculiar (mCP) stars of the upper main sequence exhibits strictly periodic light, magnetic, radio, and spectral variations that can be fully explained by the model of a rigidly rotating main-sequence…
The 'event' that triggers a gamma ray burst cannot last for more than a few seconds. This is, however, long compared with the dynamical timescale of a compact stellar-mass object ($\sim 10^{-3}$ seconds). Energy is assumed to be released as…
If strange quark matter (SQM) is the true ground state of hadronic matter, then conversion of neutron stars (NS) into quark stars (QS) could release some 10^{53} erg. We describe a scenario of burning of a NS into a hot, differentially…
We analyzed 3 years of data from the Kepler space mission to derive rotation periods of main-sequence stars below 6500 K. Our automated autocorrelation-based method detected rotation periods between 0.2 and 70 days for 34,030 (25.6%) of the…
Stars are not perfectly spherically symmetric. They are deformed by rotation and magnetic fields. Until now, the study of stellar shapes has only been possible with optical interferometry for a few of the fastest-rotating nearby stars. We…
Rotation is a critical physical process operating in the formation of Am stars. There is a strong correlation between low-velocity rotation and chemical peculiarity. However, the existence of many non-CP slow rotators challenges the…
The comparative analysis of parameters is carried out for two samples of radio pulsars. Objects of the first sample have periods P > 2 sec, the second is characterized by magnetic fields at the neutron star surface $Bs > 4.4\times10^{13}$…
We report on the detection of a planetary companion in orbit around the primary star of the binary system $\gamma$ Cephei. High precision radial velocity measurements using 4 independent data sets spanning the time interval 1981--2002…
In a previous paper, using an equation of state of dense matter representing a fluid of Skyrmions we constructed the corresponding non-rotating compact-star models in hydrostatic equilibrium; these are mostly fluid stars (the Skyrmion…
The spin periods of the ten observed Anomalous X-ray Pulsars and Soft Gamma-ray Repeaters lie in the very narrow range 6-12 s. We use a point likelihood technique to assess the constraints this clustering imposes on the birth period and on…
Observations of early-type M stars suggest that there are two characteristic cycle times, one of order one year for fast rotators ($P_{\rm rot} < 1$ day) and another of order four years for slower rotators. For a sample of fast-rotating…
Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of sub-stellar companions by their hosting stars. In the…
We present an analysis of the apsidal motion and light curve parameters of 54 never-before-studied galactic Algol-type binaries. This is the first analysis of such a large sample of eccentric eclipsing binaries in our Galaxy, and has…
The present study reports the discovery of Sun-like stars, namely main-sequence stars with $T_{\rm eff}$, $\log g$ and rotation periods $P_{rot}$ similar to solar values, presenting evidence of surface differential rotation. An…
Using publicly available gamma-rays data from the Fermi satellite and the Fermitools package, we constructed 867-day light curves of Sagittarius A* to search for potential periodicities from 2008 to 2024. By applying statistical and…