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eROSITA science book: mapping the structure of the energetic universe
eROSITA is the primary instrument on the Russian SRG mission. In the first four years of scientific operation after its launch, foreseen for 2014, it will perform a deep survey of the entire X-ray
Coronal properties of planet-bearing stars
Context. Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime,
X-rays from accretion shocks in T Tauri stars: The case of BP Tau
We present an XMM-Newton observation of the classical T Tauri star BP Tau. In the XMM-Newton RGS spectrum the O  triplet is clearly detected with a very weak forbidden line indicating high plasma
XMM-Newton X-ray spectroscopy of classical T Tauri stars
We present results from a comparative study of XMM-Newton observations of four classical T Tauri stars (CTTS), namely BP Tau, CR Cha, SU Aur and TW Hya. In these objects coronal, i.e. magnetic,
X-ray accretion signatures in the close CTTS binary V4046 Sgr
We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of Ovii, Neix, and Sixiii are clearly detected. Similar to the CTTS TW Hya and BP Tau, the
X-ray properties of active M dwarfs as observed by XMM-Newton
We present a comparative study of X-ray emission from a sample of active M dwarfs with spectral types M3.5-M4.5 using XMM-Newton observations of two single stars, AD Leonis and EV Lacertae, and two
X-ray emission from classical T Tauri stars: Accretion shocks and coronae?
Classical T Tauri stars (CTTS) are surrounded by actively accreting disks. According to current models material falls along the magnetic field lines from the disk with more or less free-fall velocity
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is
Coronal activity cycles in 61 Cygni
Context. While the existence of stellar analogues of the 11 years solar activity cycle is proven for dozens of stars from optical observations of chromospheric activity, the observation of clearly
Coronal activity cycles in nearby G and K stars - XMM-Newton monitoring of 61 Cygni and α Centauri
We use X-ray observations of the nearby binaries 61 Cyg A/B (K5V and K7V) and Alpha Cen A/B (G2V and K1V) to study the long-term evolution of magnetic activity in weakly to moderately active G + K