Search Publications
Identification of lambda Bootis stars using IUE spectra. I. Low resolution data
Solano, E.; Paunzen, E.
An analysis of the stars included in the catalogue of lambda Bootis stars by Paunzen et al. (1997) and which also have IUE observations is presented here. Population I A-F type stars as well as field horizontal branch stars were also included in the analysis. Using line-ratios of carbon to heavier elements (Al and Ni) allows us to establish unambi…
High velocity gas and dust evolution in Chamaeleon clouds
Boulanger, Francois; Falgarone, Edith; Gry, Cecile +2 more
We report on GHRS observations which reveal conspicuous differences in the absorption spectra of two nearby stars, close to each other. The star HD102065 lies behind a cloud in Chamaeleon with unusually strong mid-IR emission, indicating a large abundance of very small dust particles. Along this line of sight, 5% of the gas (about 6 10(19) cm(-2) …
Absolute measurements of trigonometric parallaxes with astrometric satellites
Makarov, V. V.
The concept of absolute trigonometric parallax measurements is formulated in strict mathematical terms, in connection with the widely discussed plans for a future astrometric space mission. The parallaxes determined for a large number of stars spread all over the sky are absolute if the expected error (accidental or systematic) of the zero-point, …
HIP 60350: an extreme runaway star
Paunzen, E.; Maitzen, H. M.; Wagner, R. M. +2 more
Using Hipparcos proper motion as well as published and our own radial velocity data we identify HIP 60350 as fastest young B-type runaway star ejected 20 Myr ago or slightly less from the galactic plane, probably at a distance from the galactic center corresponding to spiral arm -II. Both the LSR velocity (417 kms(-1) ) and the mass of the star po…
Decomposition of the rotation curves of distant field galaxies
Möllenhoff, C.; Fuchs, B.; Heidt, H.
We present decompositions of the rotation curves of distant spiral galaxies into contributions due to their bulges, disks, and putative dark haloes. In order to set constraints on the ambiguities of the decompositons we interpret the morphology of the spiral structures quantitatively in the framework of density wave theory. Galaxy models constrain…
Evolutionary status and age spread in the young LMC cluster NGC 1850A
Caloi, V.; Cassatella, A.
IUE spectra have been obtained for 15 members of the very young LMC cluster NGC 1850A. The extinction law toward the cluster is similar to the one generally accepted for the 30 Dor region. We derive the effective temperatures and bolometric luminosities to estimate the age and mass for each star. An age spread of 2 to 10 Myr is estimated, suggesti…
Compact HII regions in the Large Magellanic Cloud observed by ISO
Comeron, F.; Claes, P.
We present ISOCAM observations of five fields in the Large Magellanic Cloud centered on IRAS point sources with colors of ultracompact HII regions. Three bright sources of parsec or subparsec size, with luminosities consistent with being embedded O stars, are detected at 15 mu m in two fields belonging to the HII region N 159. Using published high…
ISO observations of the GRB 970402 error box
Altieri, B.; Palazzi, E.; Frontera, F. +12 more
Following the detection by BeppoSAX of GRB 970402, a Target-of-Opportunity Observation by ISO was scheduled for 5 April, about 55-hours after the event, i.e. simultaneous with a second BeppoSAX pointing. The CAM instrument was used in the 6('') /pixel mode, in the 8-15 mu m band (IRAS) for covering the entire BeppoSAX GRB error box. A further obse…
IUE high-resolution observations of the symbiotic star CHCygni: confirmation of the triple-star model
Bode, M. F.; Drechsel, H.; Skopal, A. +1 more
We present and analyse ultraviolet high-resolution spectra of CHCyg taken during the whole period of the International Ultraviolet Exploler (IUE) mission. Our analysis of the observed variation in the line spectrum confirms a triple-star model recently suggested for CHCyg. Radial velocities of emission lines, which are subject to eclipse in the sy…
Time-correlation of the solar p-mode velocity signal from GOLF
Roca Cortes, T.; Ulrich, R. K.; Grec, G. +5 more
Since the launch of SOHO, the Solar Heliospheric Orbital Observatory, the helioseismic observations are nearly uninterrupted. The GOLF instrument (A. Gabriel et al., 1997) measures the mean velocity integrated over the disk. The autocorrelation function of this velocity shows two main features: Firstly, the initial decrease of the peak amplitudes …