Search Publications
Calcium to hydrogen line ratios in solar prominences
Heinzel, P.; Gouttebroze, P.
The ratio of Ca II 8542 Å to Hβ line intensities has been used for a long time to diagnose the gas pressure in solar prominences. In this paper we reconsider the theoretical dependence of E(8542)/E(Hβ ) on the gas pressure, as originally computed by Heasley & Milkey (1978), and extend this theoretical correlation to higher pressures. Firstly, …
ISO observations of low and moderate albedo asteroids. PHT-P and PHT-S results
Barucci, M. A.; Dotto, E.; Müller, T. G. +4 more
The ISO observations presented here are devoted to low and moderate albedo asteroids, which are supposed to be among the more primitive objects of the solar system. Spectroscopic and multi-filter photometric data of 77 Frigga, 114 Kassandra, 308 Polyxo, 511 Davida, and 914 Palisana have been obtained by the ISO instrument ISOPHOT. The subsystem PH…
The star cluster system of the NGC 7673 starburst
Gallagher, J. S., III; Homeier, N.; Pasquali, A.
We investigate the star cluster system in the starburst galaxy NGC 7673 using archival Hubble Space Telescope WFPC2 broad-band images. For the first time we are able to examine the internal structures of the prominent optical clumps in this galaxy. The clumps are composed of young stars, 16-33% of which are in bright star clusters. We identify 268…
Calibration of the distance scale from galactic Cepheids. I. Calibration based on the GFG sample
Musella, I.; Paturel, G.; Theureau, G. +3 more
New estimates of the distances of 36 nearby galaxies are presented based on accurate distances of galactic Cepheids obtained by Gieren et al. (1998) from the geometrical Barnes-Evans method. The concept of ``sosie'' is applied to extend the distance determination to extragalactic Cepheids without assuming the linearity of the PL relation. Doing so…
An ISO and IUE study of planetary nebula NGC 2440
Pottasch, S. R.; Feibelman, W. A.; Bernard Salas, J. +1 more
The infrared and ultraviolet spectra of planetary nebula
A 2.4-12 mu m spectrophotometric study with ISO of Cygnus X-3 in quiescence
Ábrahám, P.; Fuchs, Y.; Koch-Miramond, L. +2 more
We present mid-infrared spectrophotometric results obtained with the ISO on the peculiar X-ray binary Cygnus X-3 in quiescence, at orbital phases 0.83 to 1.04. The 2.4-12 mu m continuum radiation observed with ISOPHOT-S can be explained by thermal free-free emission in an expanding wind with, above 6.5 mu m, a possible additional black-body compon…
Structure and evolution of FK Comae corona
Gondoin, P.; Lumb, D.; Erd, C.
FK Comae (HD 117555) is a rapidly rotating single G giant whose distinctive characteristics include a quasisinusoidal optical light curve and high X-ray luminosity. FK Comae was observed twice at two weeks interval in January 2001 by the XMM-Newton space observatory. Analysis results suggest a scenario where the corona of FK Comae is dominated by …
An analysis of STIS HST UV spectra of M 33 early B supergiants
Kudritzki, R. P.; Herrero, A.; Bresolin, F. +3 more
We present terminal velocities of M 33 B-supergiants, obtained from STIS HST spectra as part of our programme to investigate the Wind Momentum - Luminosity Relationship (WLR) in the Local Group. Terminal velocities are derived from their N V, C Iv, and Si Iv resonance lines in UV spectra. Comparing with IUE spectra of Galactic B-supergiants we fou…
The X-ray afterglow of GRB 020322
Ehle, M.; Watson, D.; O'Brien, P. T. +4 more
The spectrum of the afterglow of GRB 020322 is the highest-quality X-ray spectrum of a GRB afterglow available to date. It was detected by XMM-Newton in an observation starting fifteen hours after the GRB with a mean 0.2-10.0 keV observed flux of 3.5+/-0.2*E-13 erg cm-2 s-1, making it the brightest X-ray afterglow …
A 60 pc counter-rotating core in NGC 4621
Copin, Y.; Emsellem, E.; Wernli, F.
We present adaptive optics assisted OASIS integral field spectrography of the S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and dispersion) reveal the presence of a ~ 60 pc diameter counter-rotating core (CRC), the smallest observed to date. The OASIS data also suggests that the kinematic center of the CRC is slightly…