Search Publications
Kinematical trends among the field horizontal branch stars
de Boer, Klaas S.; Altmann, Martin
Horizontal branch (HB) stars in the field of the Milky Way can be used as tracers for the study of early stages of the evolution of our galaxy. Since the age of individual HB stars is not known a priori, we have studied the kinematics of a sample of field HB stars measured with Hipparcos to look for signs of age and population nature. Our sample c…
Deep far infrared ISOPHOT survey in ``Selected Area 57". I. Observations and source counts
Nørgaard-Nielsen, H. U.; Ábrahám, P.; Lemke, D. +7 more
We present here the results of a deep survey in a 0.4 deg2 blank field in Selected Area 57 conducted with the ISOPHOT instrument aboard ESAs Infrared Space Observatory (ISO at both 60 mu m and 90 mu m. The resulting sky maps have a spatial resolution of 15 x 23 arcsec2 per pixel which is much higher than the 90 x 90 arcsec
Resolved stellar populations of super-metal-rich star clusters in the bulge of M 31
Magain, P.; Jablonka, P.; Sarajedini, A. +3 more
We have applied the MCS image deconvolution algorithm (Magain et al. 1998) to HST/WFPC2 V, I data of three M 31 bulge globular clusters (G170, G177, and G198) and control fields near each cluster. All three clusters are clearly detected, with an increase in stellar density with decreasing radius from the cluster centers; this is the first time tha…
UV light curves of thermonuclear supernovae
Sorokina, E. I.; Blinnikov, S. I.
Ultraviolet light curves are calculated for several thermonuclear supernova models using a multifrequency radiation hydrodynamic code. It is found that Chandrasekhar-mass models produce very similar light curves both for detonation and deflagration. Sub-Chandrasekhar-mass models essentially differ from ``normal'' Chandrasekhar ones regarding behav…
RX J1313.2-3259, a missing link in CV evolution?
Gänsicke, B. T.; Beuermann, K.; de Martino, D. +1 more
We present low-state IUE spectroscopy of the ROSAT-discovered polar RX J1313.2-3259. The SWP spectrum displays a broad Lyalpha absorption profile, which can be fitted with a two-temperature model of a white dwarf of T_wd=15 000 K with a hot spot of T_spot=34 000 K which covers f ~ 0.01 of the white dwarf surface. The white dwarf temperature is aty…
Shock excited far-infrared molecular emission around T Tau
White, G. J.; Palla, F.; Pezzuto, S. +9 more
The first complete far-infrared spectrum of T Tau has been obtained with the LWS spectrometer on-board the Infrared Space Observatory (ISO), which detected strong emission from high-J (J=14-25) CO, para- and ortho-H_2O and OH transitions over the wavelength range from 40 to 190 mu m. In addition the [OI]63mu m, [OI]145mu m and [CII]158mu m atomic …
SUMER observations of transition region fine structures
Mason, H. E.; Landini, M.; Lemaire, P. +1 more
The SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on SOHO (Solar and Heliospheric Observatory) provides an opportunity to observe and study the solar transition region with high spatial and spectral resolution. We present new evidence to confirm that the emission from the quiet Sun at 2x 105 K is dominated by co…
Hydrogen temperature gradient in the transition region of a solar coronal hole
Wilhelm, K.; Tu, C. -Y.; Marsch, E.
The Lyman series of hydrogen was observed by SUMER on SOHO on the north polar limb of the Sun with a total exposure time of more than ten hours. The resulting line profiles have been analysed using the technique described by Marsch et al. (1999). The data analysis corroborates earlier findings on the Lyman lines, but also yields phenomena which ca…
The Sombrero galaxy. III. Ionised gas and dust in the central 200 pc: a nuclear bar?
Emsellem, E.; Ferruit, P.
We present the results of new 3D TIGER spectroscopic observations and archived HST/WFPC2 and NICMOS images of the central region of M 104. The [N ii]+Hα images reveal the presence of a nuclear spiral structure, and the gaseous kinematics in the central arcsecond shows evidence for kinematical decoupling of the central peak. A straight nuclear dust…
DENIS and ISOGAL properties of variable star candidates in the Galactic Bulge
Alard, C.; Blommaert, J. A. D. L.; Ganesh, S. +9 more
Repeated DENIS observations (summer 1996 & 1998) in the J (1.25 mu m) and the KS (2.15 mu m) bands are used to look for variable stars. We present two catalogues of ~ 1000 probable variables in an area of ~ 4 deg2 of the inner galactic bulge. The first one contains ~ 720 variable star candidates which show variability in …