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On the outflow in an equatorial coronal hole
Marsch, E.; Curdt, W.; Xia, L. D.
We report new observations concerning the source of the fast solar wind by directly comparing Doppler-shift maps of Ne7+ with charts of the photospheric magnetic field in an equatorial coronal hole, which was observed by SUMER/SOHO and NSO/Kitt Peak on November 5, 1999. The relationship between the velocity field, line intensity and mag…
Rotation, pulsations and magnetic field in V 2052 Ophiuchi : A new He-strong star
Frémat, Y.; Neiner, C.; Jankov, S. +7 more
Three years in the coronal life of AB Dor. I. Plasma emission measure distributions and abundances at different activity levels
Sanz-Forcada, J.; Micela, G.; Maggio, A.
The young active star AB Dor (K1 IV-V) has been observed 16 times in the last three years with the XMM-Newton and Chandra observatories, totalling 650 ks of high-resolution X-ray spectra. The XMM/RGS observations with the highest and lowest average emission levels have been selected to study the coronal properties of AB Dor in two different activi…
Nearby young stars
Schmitt, J. H. M. M.; Hubrig, S.; Wichmann, R.
We present the results of an extensive all-sky survey of nearby stars of spectral type F8 or later in a systematic search of young (zero-age main sequence) objects. Our sample has been derived by cross-correlating the ROSAT All-Sky Survey and the TYCHO catalogue, yielding a total of 754 candidates distributed more or less randomly over the sky. Fo…
The mass and energy budget of Cassiopeia A
Kaastra, J. S.; Bleeker, J. A. M.; Willingale, R. +1 more
Further analysis of X-ray spectroscopy results (Willingale et al. \cite{Wil02}) recently obtained from the MOS CCD cameras on-board XMM-Newton provides a detailed description of the hot and cool X-ray emitting plasma in Cas A. Measurement of the Doppler broadening of the X-ray emission lines is consistent with the expected ion velocities, ~ 1500 k…
Discovery of a quiescent neutron star binary in the globular cluster M 13
Barret, D.; Webb, N.; Gendre, B.
We have discovered with XMM-Newton an X-ray source in the core of the globular cluster M 13, whose X-ray spectral properties suggest that it is a quiescent neutron star X-ray binary. The spectrum can be well fitted with a pure hydrogen atmosphere model, with Tinfty =76+/-3 eV, Rinfty =12.8+/-0.4 km and an X-ray luminosity of …
VLBI astrometry of circumstellar OH masers: Proper motions and parallaxes of four AGB stars
Schilizzi, R. T.; Habing, H. J.; Vlemmings, W. H. T. +2 more
The main-line OH masers around 4 AGB stars have been observed with the NRAO Very Long Baseline Array (VLBA) at 8 epochs over a period of 2.5 yrs. Using a phase referencing technique, the position of the most compact maser spot of each star was monitored with respect to two extragalactic reference sources. For U Her and W Hya, we observe the most b…
The radiative response of solar loop plasma subject to transient heating
Mason, H. E.; Bradshaw, S. J.
In Bradshaw & Mason (\cite{Bradshaw2003}) we carried out a hydrodynamic simulation of a cooling solar loop and investigated the nonequilibrium response of the population of C VII ions to the changing conditions in the plasma. We also compared equilibrium and nonequilibrium calculations of the total plasma emissivity. In this paper we present t…
Gemini observations of Wolf-Rayet stars in the Local Group starburst galaxy IC 10
Smartt, S. J.; Crowther, P. A.; Royer, P. +2 more
We present Gemini-N GMOS and CFHT MOS spectroscopy of Wolf-Rayet candidates in the Local Group dwarf galaxy IC 10 that were previously identified by Massey et al. and Royer et al. From the present spectroscopic survey, the WC/WN ratio for IC 10 remains unusually high, given its low metallicity, although none of the WC9 stars suspected from narrow-…
The pre-main sequence spectroscopic binary AK Scorpii revisited
Andersen, J.; Alencar, S. H. P.; Batalha, C. +4 more
We present an analysis of 32 high-resolution echelle spectra of the pre-main sequence spectroscopic binary AK Sco obtained during 1998 and 2000, as well as a total of 72 photoelectric radial-velocity observations from the period 1986-1994. These data allow considerable improvement of the period and other orbital parameters of AK Sco. Our analysis …