Related papers: Quiescent and flare analysis for the chromospheric…
IIPeg is an ideal target to study stellar activity and flares, since intense and long lasting flares have been frequently detected from this system at all wavelengths. We report here about a BeppoSAX observation of IIPeg. We followed the…
We present a long (150 ks elapsed time) ASCA X-ray observation of the dM3.5e star EV Lac, during which an exceptionally intense flaring event (lasting approximately 12 ks) was observed: at the flare's peak, the X-ray count rate in the ASCA…
A large sample of over 38,000 chromospherically active candidate solar-like stars and cooler dwarfs from the RAVE survey is addressed in this paper. An improved activity identification with respect to the previous study was introduced to…
We present results of a systematic search for X-ray flares on young stars observed during ROSAT PSPC observations of the Taurus-Auriga-Perseus region. All pointed PSPC observations currently available from the ROSAT Public Data Archive with…
We gathered high resolution spectra for an ensemble of 55 bright active and inactive stars using the ARC 3.5 m Telescope Echelle Spectrograph at Apache Point Observatory ($R\approx$31,500). We measured spectroscopic effective temperatures,…
Stellar flares are short-duration ($<$ hours) bursts of radiation associated with surface magnetic reconnection events. Stellar magnetic activity generally decreases as a function of both age and Rossby number, $R_0$, a measure of the…
Coronal density, temperature and heat flux distributions for the equatorial and polar corona have been deduced by Lemaire [2012] from Saito's model of averaged coronal white light (WL) brightness and polarization observations. They are…
Standing long-period (with the periods longer than several minutes) oscillations in large hot (with the temperature higher than 3 MK) coronal loops have been observed as the quasi-periodic modulation of the EUV and microwave intensity…
Observations of He-like and H-like Ar (Ar XVII and Ar XVIII) lines at 3.949 Angstroms and 3.733 Angstroms respectively with the RESIK X-ray spectrometer on the CORONAS-F spacecraft, together with temperatures and emission measures from the…
Open-shutter RHESSI observations of 3-15 keV X-rays are found to exhibit active region transient brightenings and microflares at a rate of at least 10 per hour occurring even during the periods of lowest solar activity so far in the…
We present Submillimeter Array observations, in the 1.3 mm continuum and the CH_3CN(12-11) line of 17 hot molecular cores associated with young high-mass stars. The angular resolution of the observations ranges from 1".0 to 4".0. The…
We analyzed X-Shooter/VLT spectra of 24 ClassIII sources from three nearby star-forming regions (sigmaOrionis, LupusIII, and TWHya). We determined the effective temperature, surface gravity, rotational velocity, and radial velocity by…
We report molecular line observations, made with ASTE and SEST, and dust continuum observations at 0.87 mm, made with APEX, towards the cold dust core G305.136+0.068. The molecular observations show that the core is isolated and roughly…
Context. LQ Hya is one of the most frequently studied young solar analogue stars. Recently, it has been observed to show intriguing behaviour by analysing long-term photometry: during 2003--2009, a coherent spot structure migrating in the…
Quiescent filaments appear as absorption features on the solar disk when observed in chromospheric lines and at continuum wavelengths in the millimeter (mm) range. Active region (AR) filaments are their small-scale, low-altitude analogues,…
While the temperature of the X-ray corona ($\rm{kT_e}$) in active galactic nuclei (AGN) are known for many sources, its variation, if any, is limited to a handful of objects. This is in part due to the requirement of good signal-to-noise…
Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity $>$3~keV are now enabled by…
Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as $2.5 \times 10^9$ Amperes (Spangler 2007). These estimates of currents are used to…
The soft X-ray emissions of solar flares come mainly from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy,…
We investigate quasi-periodic coronal pulsations during the decay phase of an X 3.2 class flare on 14 May 2013, using soft X-ray data from the RHESSI satellite. Periodogram analyses of soft X-ray light curves show that 53 s and 72 s periods…