eROSITA is poised to unleash a deluge of information on the stellar X-ray sky in a nexus with other powerful complementary missions and capabilities, such as TESS, Gaia and LSST. I will endeavour to provide a brief overview of the outstanding problems in high energy stellar physics, and the status of our knowledge deep into the Chandra and XMM-Newton era. I will describe some important aspects...
Ultracool dwarfs (UCDs) are objects with spectral type M7 and later, at the age-dependent transition between stellar and brown dwarf regime. In the predominantly neutral photospheres of UCDs the magnetic field and the matter are expected to show poor coupling, and this should be shutting off the magnetic activity. Nevertheless, radio, Halpha and X-ray emission has occasionally been observed...
We have developed a fully Bayesian scheme to statistically
extract the full stellar source content in the eROSITA all-sky survey.
The identification scheme heavily relies on Gaia data, since
all coronal X-ray sources should have a Gaia counterpart with
significant parallax, and assigns to every X-ray source
a probability with which a given X-ray source is stellar. With
our chosen priors the...
The eta Chamaeleontis cluster is a nearby, moderately dispersed star forming region at an intermediate age of 5-10 Myr. Its members are prime targets to study pre-main sequence evolutionary models, accretion properties, disc dispersal and planet formation and are repeatedly observed by major ground and space based facilities. The cluster has been observed by eROSITA in mid November 2019 in the...
Massive stars of basically all spectral types emit X-rays. Despite tremendous efforts undertaken in the last 20 years, the exact physical mechanisms responsible for their X-ray emission are still not fully understood. The eROSITA survey will deliver a clear X-ray view of massive stars within 2 kpc from the sun. eROSITA's sensitivity in the hard band will become a key diagnostic tool to detect...
It is now firmly established that remnant planetary systems orbit and pollute the surfaces of white dwarf stars with heavy elements, providing a unique empirical tool to assess the bulk composition of extrasolar planetary bodies. Yet despite the existence of myriad stars polluted by up to 15 heavy elements, and (self-consistent) model inferences for their mass accretion rates, there remains no...
