Search Publications
What can HST-GHRS Fe II observations of α Orionis (M2 Iab) tell us about short-period heating?
Cuntz, M.; Harper, G. M.; Bennett, P. D.
Cuntz (\cite{Cuntz97}) suggested that apparent velocity shifts in Fe II emission lines observed in Betelgeuse (alpha Orionis: M2 Iab) indicate that non-magnetic wave modes are relevant for the heating and dynamics of alpha Ori's chromosphere. This claim was based on the similarity of computed stochastic velocities in 1-D short-period acoustic wave…
HD 169981 - an overlooked photometric binary?
Lehmann, H.; Scholz, G.; Hildebrandt, G. +1 more
In 1999 and 2000 we obtained spectroscopic and photometric observations of the A-type binary star HD 169981. The observations were part of a campaign to search for short-term photometric and radial-velocity variations among early-type binaries. From the radial velocities of 18 metal lines we derived more precise orbital elements. Quite unexpectedl…
The comparative accuracy of photographic observations of radio stars observed at the Engelhardt Astronomical Observatory
Rizvanov, N.; Dautov, I.; Shaimukhametov, R.
At the Engelhardt Astronomical Observatory (EAO), we observed photographic positions of 113 Galactic Radio Sources (GRS) in the system PPM catalogue (Rizvanov & Dautov 1998). Analysis of their accuracy is made by comparison with the Hipparcos catalogue (Perryman et al. 1997) and astrometric catalogue of radio stars in the radio window from the…
The Tycho-2 catalogue of the 2.5 million brightest stars
Makarov, V. V.; Bastian, U.; Fabricius, C. +6 more
The Tycho-2 Catalogue presented here is an astrometric reference catalogue containing positions and proper motions as well as two-colour photometric data for the 2.5 million brightest stars in the sky. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1) collected by …
Revision of the initial-to-final mass relation
Weidemann, V.
The initial-to final mass relation is revised in view of new theoretical and observational data. Recent stellar evolution models predict core masses at the beginning of the thermally pulsing asymptotic giant branch which practically coincide with final white dwarf masses derived for NGC 3532 and the binary white dwarf PG 0922+162. The Hyades white…
Mid-infrared diagnostics to distinguish AGNs from starbursts
Cesarsky, C.; Madden, S. C.; Sauvage, M. +5 more
We present new mid-infrared (MIR) diagnostics to distinguish emission of active galactic nuclei (AGN) from that originating in starburst regions. Our method uses empirical spectroscopic criteria based on the fact that MIR emission from star forming or active galaxies arises mostly from HII regions, photo-dissociation regions (PDRs) and AGNs. The a…
ISO-SWS spectra of galaxies: Continuum and features
Lutz, D.; Genzel, R.; Sturm, E. +5 more
We present an inventory of mid-infrared spectral features detected in high resolution (R ~ 1500) ISO-SWS 2.4-45mu m spectra of the galaxies
An ISOCAM absorption survey of the structure of pre-stellar cloud cores
Abergel, A.; Puget, J. -L.; Bontemps, S. +3 more
We present the results of a mid-infrared (lambda =~ 7 mu m) imaging survey of a sample of 24 starless dense cores carried out at an angular resolution of 6arcsec with the ISOCAM camera aboard the Infrared Space Observatory (ISO). The targeted cores are believed to be pre-stellar in nature and to represent the initial conditions of low-mass, isolat…
The Nature of the lithium rich giants. Mixing episodes on the RGB and early-AGB
Charbonnel, C.; Balachandran, S. C.
We present a critical analysis of the nature of the so-called Li-rich RGB stars. For a majority of the stars, we have used Hipparcos parallaxes to determine masses and evolutionary states by comparing their position on the Hertzsprung-Russell diagram with theoretical evolutionary tracks. Among the twenty Li-rich giants whose location on the HR dia…
Construction and verification of the Tycho-2 Catalogue
Makarov, V. V.; Bastian, U.; Fabricius, C. +6 more
The construction of the Tycho-2 Catalogue is described. The catalogue contains astrometric positions and proper motions as well as two-colour photometric data for 2.5 million stars. The Tycho-2 positions and magnitudes are based on precisely the same observations as the original Tycho Catalogue (hereafter Tycho-1) collected by the sky mapper of th…