Related papers: Stellar Coronal Spectroscopy with the Chandra HETG…
Recent simultaneous multiwavelength observations of a nearby young solar-type star EK Dra in the optical, H$\alpha$ spectrum, and X-ray, have provided evidence for stellar prominence eruptions associated with superflares. The large…
The high-resolution X-ray spectroscopy made possible by the 1999 deployment of the Chandra X-ray Observatory has revolutionized our understanding of stellar X-ray emission. Many puzzles remain, though, particularly regarding the mechanisms…
We have re-analyzed using a hydrodynamic model large flaring events on three different categories of pre-main sequence (PMS) stars: the young stellar object (YSO) YLW 15, the classical T Tauri star (CTTS) LkHalpha92, the weak-line T Tauri…
Aims. The H-alpha emission of solar flare kernels and associated hard X-ray (HXR) emission often show similar time variations but their light curves are shifted in time by energy transfer mechanisms. We searched for fast radiative response…
Young and magnetically active low-mass stars often exhibit non-thermal coronal radio emission due to the gyration of electrons in their magnetized chromospheres. This emission is easily detectable at centimeter wavelengths with the current…
Stellar activity influences radial velocity (RV) measurements and can also mimic the presence of orbiting planets. As part of the search for planets around the components of wide binaries performed with the SARG High Resolution Spectrograph…
We report on the coronal activity cycles of our stellar neighbors alpha Centauri A/B. The binary has been monitored with XMM-Newton since 2002 to study the long-term evolution of coronal activity evolution in X-rays. The solar analog alpha…
We obtained radio observations of the symbiotic binary and known recurrent nova T Coronae Borealis following a period of increased activity in the optical and X-ray bands. A comparison of our observations with those made prior to 2015…
Using the Wide Field Grism Spectrograph 2 (WFGS2), we have carried out slit-less spectroscopy, g'r'i' photometry, and slit spectroscopy on the L1014 dense core. We detected three Halpha emission line stars. We interpret one as weak-line T…
At radio wavelengths, solar-type stars emit thermal free-free and gyroresonance, gyrosynchrotron, and impulsive coherent emission. Thermal free-free emission originates at layers where the optical depth is close to unit, while high…
We use the data of the Chandra Orion Ultradeep Project (COUP) to study the nearly 600 X-ray sources that can be reliably identified with optically well characterized T Tauri stars (TTS) in the Orion Nebula Cluster. We detect X-ray emission…
Context : The peculiar hot star Theta Car in the open cluster IC2602 is a blue straggler as well as a single-line binary of short period (2.2d). Aims : Its high-energy properties are not well known, though X-rays can provide useful…
We observed the classical T Tauri star TW Hya with \textit{HST}/STIS using the E140M grating, from 1150--1700 \AA, with the E230M grating, from 2200--2900 \AA, and with \FUSE from 900--1180 \AA. Emission in 143 Lyman-band H$_2$ lines…
We present the Chandra High Energy Transmission Grating Spectrometer (HETGS) and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main sequence group in the Lambda Orionis Cluster. Our high spatial…
High resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range 0.4-8.0 keV (1.5-30 Angstroms) show a large number of emission lines, demonstrating the performance of the HETGS. A preliminary application of…
The Chandra X-ray Observatory has completed a remarkable twenty years in orbit. A large part of the science program of Chandra during this time has involved the study of stars and their planetary systems. This primer aims to give the reader…
Theta 1 Ori E is a young, moderate mass binary system, a rarely observed case of spectral-type G-giants of about 3 Solar masses, which are still collapsing towards the main sequence. We have obtained high resolution X-ray spectra with…
The low resolution X-ray spectra around $\eta$ Car covering Tr 16 and part of Tr 14 have been extracted from a Chandra CCD ACIS image. Various analysis techniques have been applied to the spectra based on their count rates. The spectra with…
Stellar flares have been extensively studied in soft X-rays (SXR) by basically every X-ray mission. Hard X-ray (HXR) emission from stellar superflares, however, have only been detected from a handful of objects over the past years. One very…
Variability of Classical T Tauri Systems (CTTS) occurs over a vast range of timescales. CTTS in particular are subject to variability caused by accretion shocks which can occur stochastically, periodically, or quasi-periodically on…