Related papers: Discovery of X-ray flaring on the magnetic Bp-star…
The X-ray emission of magnetic intermediate mass Ap/Bp stars is reviewed and put into context of intrinsic as well as extrinsic hypotheses for its origin. New X-ray observations of Ap/Bp stars are presented and combined with an updated…
Hard X-ray emissions from a Herbig Be star MWC297 were discovered in three separate observations spanning 5 days in April 1994 with the Advanced Satellite for Cosmology and Astrophysics (ASCA). An X-ray flare was found at the beginning of…
According to recent observations relative number of flare stars does not change very much from cool dwarfs to hot A stars. Flare energies are strongly correlated with stellar luminosity and radius. Whence it follows that the typical…
(abridged) As the favoured progenitors of long-duration gamma-ray bursts, massive stars may represent our best signposts of individual objects in the early Universe, but special conditions seem required to make these bursters, which might…
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…
We used the Aladin Virtual Obsrvatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the sigma Orionis cluster and a background galaxy. Five stars displayed…
The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization…
Spectroscopic observations provide evidence that the optical transient object observed in 1966 on archival plates of Sonneberg Observatory is a B=18.5 dMe star. For an assumed flare duration of 40 min. (or longer) the flare amplitude was…
BIMA observations of the Orion nebula discovered a giant flare from a young star previously undetected at millimeter wavelengths. The star briefly became the brightest compact object in the nebula at 86 GHz. Its flux density increased by…
In 2018, XMM-Newton observed the awakening in X-rays of the Be/X-ray binary (Be/XRB) A0538-66. It showed bright and fast flares close to periastron with properties that had never been observed in other Be/XRBs before. We report the results…
We have conducted multi-epoch synthesis imaging of 2 and 3 millimeter (mm) continuum emission and near infrared K band 2.2 um imaging of a flare event in January 2003 that occurred on the young stellar object GMR-A which is suggested to be…
The X-ray emission from X-ray binaries may originate in flares occurring when magnetic loops anchored in the disc reconnect. In analogy with our Sun, H alpha emission should arise as the accelerated electrons thermalize in the optically…
We present the first X-ray observation of an oscillation during a stellar flare. The flare occurred on the active M-type dwarf AT Mic and was observed with XMM-Newton. The soft X-ray light curve (0.2-12 keV) is investigated with wavelet…
Massive B and Be stars produce X-rays from shocks in high velocity winds with temperatures of a few million degrees and maximum X-ray luminosities of $\approx$ 10$^{31}$ erg/s. Surprisingly, a sub-group of early Be stars exhibits > 20 times…
Context. Class 0 protostars represent the earliest evolutionary stage of solar-type stars, during which the majority of the system mass resides in an infalling envelope of gas and dust and is not yet in the central, nascent star. Although…
We present the results of a campaign to observe flares on the M dwarf flare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet…
Stellar flares are an intense stellar activity that can significantly impact the atmospheric composition of the surrounding planets and even the possible existence of life. During such events, the radiative energy of the star is primarily…
23 giant flares from 13 active stars (eight RS CVn systems, one Algol system, three dMe stars and one YSO) were detected during the first two years of our all-sky X-ray monitoring with the gas propotional counters (GSC) of the Monitor of…
(Abridged) We report results from a comprehensive study of the nearby M dwarf Proxima Centauri with the XMM-Newton satellite. We find strongly variable coronal X-ray emission, with flares ranging over a factor of 100 in peak flux. The…
Astronomical observations of flares from analogs of the early Sun have the potential to give critical insights into the high energy irradiation environment of protoplanetary disks. Solar-mass young stellar objects are significantly more…