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The large-scale distribution of X-ray active stars
Schmitt, J. H. M. M.; Motch, C.; Guillout, P. +4 more
We analyse the large-scale sky distribution of 8593 X-ray emitting stars from the cross-correlation of the ROSAT All-Sky Survey sources with the Tycho catalog. We detect a density gradient from the galactic plane to the galactic pole which is attributed to the scale height of the young late type star population of the galactic disc. The data also …
On the mass-loss of PG1159 stars
Rauch, T.; Dreizler, S.; Koesterke, L.
The winds of the four PG1159 stars NGC7094, NGC246, K1-16 and RXJ2117.1+3412 are investigated by means of non-LTE models for spherically expanding atmospheres. Based on the results of recent plane-parallel non-LTE analyses, several individual models with various mass-loss rates are calculated. Synthetic profiles of the C Iv resonance line are comp…
Detection of the ``44 MU m'' band of water ice in absorption in combined ISO SWS-LWS spectra
Heras, A. M.; Tielens, A. G. G. M.; Cox, P. +8 more
We report the detection of the transverse optical vibrational band of water ice at 44 microns in absorption towards two embedded infrared sources, IRAS 18316-0602 (RAFGL7009S) and IRAS 19110+1045. The water band extending from 30 to about 80 microns is a prominent feature in the combined ISO SWS and LWS grating spectra. Using new optical constants…
CO observations and mass loss of MS- and S-stars
Groenewegen, M. A. T.; de Jong, T.
We present (12) CO J = 1-0 and 2-1 observations of 14 S-stars, and report 6 new detections. Two stars were observed in the (13) CO J = 1-0 and 2-1 lines, and one tentative 2-1 detection is reported. A compilation is presented of all CO observations of S-stars. The stars in this sample are separated into ``intrinsic'' and ``extrinsic'' S-stars, bas…
Deep ISOCAM view of the core of the lensing cluster A2390
Elbaz, D.; Pierre, M.; Vigroux, L. +4 more
We have imaged the inner square arcminute of the well known lensing and cooling flow cluster A2390 (z = 0.23) down to a sensitivity of 65 and 130 mu Jy at 6.75 and 15 mu m, respectively. We report the first evidence of an active star-forming region in a cooling flow (at those wavelengths) and strong emission in the mid-IR from lensed galaxies loca…
Origin and production of C(^1D) atoms in cometary comae
Feldman, P. D.; Festou, M. C.; Tozzi, G. P.
The abundance of carbon atoms in the metastable (1) D state near the cometary nucleus provides an important diagnostic of one of the principal sources of carbon in the cometary coma. This quantity may be determined in two independent ways: measurement of (1) D -(1) P fluorescence at 1931 Angstroms and by prompt emission of the (1) D -(3) P doublet…
New study of the quasi-molecular Lyman alpha satellites due to H-H and H-H(+) collisions
Gerbaldi, M.; Allard, N. F.; Kielkopf, J. +2 more
We present new theoretical calculations of the total profile of the atomic hydrogen Lyman alpha spectral line perturbed by collisions with neutral hydrogen atoms and protons. The variation of the radiative dipole moment during the collision is taken into account. This leads to an increase in the amplitude of the main spectral line satellites and t…
The nature of isolated T Tauri stars
Henning, Thomas; Hoff, Wilhelm; Pfau, Werner
We present the results of a search for young stellar objects around the two isolated T Tauri stars (TTSs) TW Hya and CoD-29degr 8887. From the spectroscopic properties of these two objects, it is obvious that they are T Tauri stars, although they are not associated with a star-forming region as it is the case for most of the known TTSs. Especially…
Unveiling the nature of the Cloverleaf lens-system: HST/NICMOS-2 observations
Kneib, J. -P.; Alloin, D.; Pello, R.
We present new elements in the identification of the Cloverleaf lens-system based on recent NICMOS-2/F160W observations. After a careful PSF subtraction of the 4 images of the quasar, the residual HF160W image reveals the presence of a faint object (H ~ 20.5) amid the 4 quasars. This object corresponds to a single galaxy that we identif…
Galactic planetary nebulae with Wolf-Rayet nuclei. I. Objects with [WC]-early type stars
Koesterke, L.; Esteban, C.; Pena, M. +3 more
Spatially resolved long-slit spectrophotometric data for the planetary nebulae PB 6, NGC 2452, NGC 2867, NGC 6905 and He 2-55 are presented. Different knots were observed in each nebula. All the nebulae are ionized by [WC 2-3] type nuclei. For the five objects, we calculated photoionization models using the ionizing radiation field from models of …