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Heliospheric and it astrospheric hydrogen absorption towards Sirius: no need for interstellar hot gas
Lallement, R.; Izmodenov, V. V.; Malama, Y. G.
We use an updated self-consistent kinetic/gasdynamic model of the solar wind/interstellar flow interaction to compute the Lyman-alpha absorption by hydrogen atoms of both interstellar and solar origin generated in the heliospheric interface. We apply this model to the direction of the star Sirius. We show that the neutralized, compressed solar win…
Detection of warm SO_2 gas in oxygen-rich AGB stars
Waters, L. B. F. M.; Onaka, T.; Yamamura, I. +2 more
We report the discovery of the nu_3 band of SO_2 at 7.3 mu m in the ISO/SWS spectra of oxygen-rich AGB stars. The band is clearly detected in three stars, UX Cyg, o Cet and T Cep, and marginally detected in at least four other stars. The band is seen in absorption in UX Cyg, while it is in emission in o Cet. Seven spectra of T Cep taken at differe…
The zabs ~ zem absorption line systems toward QSO J 2233-606 in the Hubble Deep Field South: NE viii lambda lambda 770,780 absorption and partial coverage absorption line systems toward QSO J 2233-606
Petitjean, Patrick; Srianand, R.
Results of a careful analysis of the highly ionized absorption systems, observed over the redshift range 2.198-2.2215 in the zem = 2.24 HDFS-QSO J 2233-606, are presented. The strength and covering factor of the O VI and Ne VIII absorption lines suggest that the gas is closely associated with the AGN. In addition, most of the lines show…
ISO-LWS observations of Herbig Ae/Be stars. II. Molecular lines
Liseau, R.; White, G. J.; Palla, F. +15 more
We present the first ISO-LWS observations of the molecular FIR lines in 3 out of a sample of 11 Herbig Ae/Be stars (HAEBE), namely IRAS12496-7650, RCrA and LkHα 234. High-J rotational CO lines (from Jup = 14 to Jup = 19) have been observed in all the spectra, while two (at 79 mu m and 84 mu m) and three OH lines (at 71 mu m, …
Heating events in the quiet solar corona: multiwavelength correlations
Krucker, Säm; Benz, Arnold O.
Coronal, transition region and chromospheric lines and centimeter radio emission of the quiet Sun have been simultaneously observed by SoHO and the VLA. The corona above the magnetic network has a higher pressure and is more variable than above the interior of supergranular cells. The Fourier transform in time is found to have steeper spectra in t…
A new HST measurement of the Crab Pulsar proper motion
Caraveo, P. A.; Mignani, R. P.
We have used a set of archived HST/WFPC2 exposures of the inner regions of the Crab Nebula to obtain a new measurement of the pulsar proper motion, the first after the original work of Wyckoff & Murray, more than 20 years ago. Our measurement of the pulsar displacement, mu = 18 +/- 3 mas yr(-1) , agrees well with the value obtained previously.…
ISO-LWS observations of Herbig Ae/Be stars. I. Fine structure lines
Liseau, R.; White, G. J.; Palla, F. +15 more
We present the results of the first spectrophotometric survey of a sample of eleven Herbig Ae/Be stars (HAEBE) obtained with the Long Wavelength Spectrometer (LWS) on board the Infrared Space Observatory (ISO). The [OI] 63mu m and the [CII] 158mu m lines are observed in all the investigated sources, while the [OI] 145mu m transition, due to its re…
Global X-ray emission and central properties of early type galaxies
Pellegrini, S.
Hubble Space Telescope observations have revealed that the central surface brightness profiles of early type galaxies can be divided into two types: ``core" profiles and featureless power law profiles, without cores. On the basis of this and previous results, early type galaxies have been grouped into two families. One consists of coreless galaxie…
The metal-rich globular clusters of the Milky Way
Richtler, T.; Heitsch, F.
We present new (V,V-I)-photometry of the metal-rich globular clusters
Transient supersoft X-ray emission from V 751 Cygni during the optical low-state
Greiner, J.; González-Riestra, R.; Di Stefano, R. +4 more
We have observed V 751 Cyg with the ROSAT HRI in a target-of-opportunity mode during its recent optical low state and clearly detect it at a count rate of 0.015 cts s(-1) . The X-ray intensity is a factor of 7-19 (depending on the exact X-ray spectral shape) higher than the upper limit obtained with the ROSAT PSPC during the optical high state, th…