Search Publications
X-ray Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra
Güdel, Manuel; Schmutz, Werner; Zhekov, Svetozar +1 more
We present an overview of recent X-ray observations of Wolf-Rayet (WR) stars with XMM-Newton and Chandra. These observations are aimed at determining the differences in X-ray properties between massive WR + OB binary systems and putatively single WR stars. A new XMM spectrum of the nearby WN8 + OB binary WR 147 shows hard absorbed X-ray emission (…
The Brave New World of Binary Star Studies
Guinan, Edward F.; Engle, Scott G.
In this paper we discuss some of the new and exciting developments in the study of binary stars. Recent technological advances (such as CCDs) now make it possible (even easy) to study faint, astrophysically important binaries that in the past could only be done with large 4 + meter class telescopes. Also, the panoramic nature of CCDs (and the use …
UV Capabilities to Probe the Formation of Planetary Systems: From the ISM to Planets
Cernicharo, José; Gómez de Castro, Ana I.; Linsky, Jeffrey L. +2 more
Planetary systems are angular momentum reservoirs generated during star formation. Solutions to three of the most important problems in contemporary astrophysics are needed to understand the entire process of planetary system formation: The physics of the ISM. Stars form from dense molecular clouds that contain ∼ 30% of the total interstellar medi…
The Need for Ultraviolet to Understand the Chemical Evolution of the Universe and Cosmology.
Fabian, Andrew C.; Petitjean, Patrick; Fransson, Claes +8 more
We identify an important set of key areas where an advanced observational Ultraviolet capability would have major impact on studies of cosmology and Galaxy formation in the young Universe. Most of these are associated with the Universe at z < 3–4. We address the issues associated with Dark matter evidence in the local Universe and the impact of…
Common Proper Motion Search for Faint Companions Around Early-Type Field Stars – Progress Report
Huélamo, N.; Foellmi, C.; Chauvin, G. +5 more
The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the age and the environment conditions. The few studies that have investigated this connection do not provide conclusive results. To fill in this gap, we started the first de…
Structure and Evolution of White Dwarfs and their Interaction with the Local Interstellar Medium
Werner, K.; Barstow, M. A.
The development of far-UV astronomy has been particularly important for the study of hot white dwarf stars. A significant fraction of their emergent flux appears in the far-UV and traces of elements heavier than hydrogen or helium are, in general, only detected in this waveband or at shorter wavelengths that are also only accessible from space. Al…
X-ray Emission from the Pre-Main Sequence Systems FU Orionis and T Tauri
Güdel, Manuel; Audard, Marc; Briggs, Kevin +2 more
We present new results from recent X-ray observations of the accreting pre-main sequence stars FU Orionis and T Tauri. XMM-Newton observations of the close binary system FU Ori reveal an unusual X-ray spectrum consisting of a cool moderately-absorbed component and a hot component viewed through much higher absorption. The two components thus origi…
X-rays from the Symbiotic Star RX Pup
Sokoloski, J. L.; Costa, Roberto D. D.; Luna, Gerardo J. M.
We describe X-ray and optical observations of the symbiotic star RX Pup. From low resolution optical spectra, we obtain a reddening for RX Pup of E(B‑V)=0.79. We use the neutral column density corresponding to this reddening as a lower limit for the X-ray spectra fits. The X-ray spectra can be fitted with either a two-temperarure thermal plasma mo…
A View to the Future: Ultraviolet Studies of the Solar System
Gérard, Jean-Claude; Brosch, Noah; Festou, Michel C. +1 more
We discuss the status of ultraviolet knowledge of Solar System objects. We begin with a short historical survey, followed by a review of knowledge gathered so far and of existing observational assets. The survey indicates that UV observations, along with data collected in other spectral bands, are necessary and in some cases essential to understan…
Absolute Magnitudes of Be Stars Based on Hipparcos Parallaxes
Zhang, P.; Chen, P. S.; Liu, C. Q.
The absolute visual magnitudes of 457 Be stars are determined from Hipparcos parallaxes, subsequently the mean absolute visual magnitudes of Be stars for luminosity classes III, IV and V are obtained. The new Mv calibration is compared with existing calibrations. It is found that Be stars are generally brighter than B stars of the corresponding sp…