Search Publications
Linear polarization and molecular filamentary clouds
Gahm, G. F.; Kaas, A. A.; Carlqvist, P. +1 more
We have carried out deep CCD polarimetry in the I band in selected fields in three filamentary, molecular clouds: the L1400 complex, L204, and MBM25, at galactic latitudes 4degr , 21degr , and 31degr , respectively. I magnitudes and the degree and direction of linear polarization were measured with satisfactory accuracies for 387 stars down to I=1…
On the nature of the H BT I infrared emission lines of tau Scorpii
Waters, L. B. F. M.; de Koter, A.; Geballe, T. R. +4 more
We present Hα , He i lambda 2.058 mu m and 6 hydrogen Brackett and Pfund lines of tau Sco (B0.2V) obtained using the ground-based INT and UKIRT instruments as well as satellite data from ISO. The infrared lines all show core emission. We have investigated the formation of these lines using sophisticated non-LTE models. The observed emission in the…
Gamma Persei: a challenge for stellar evolution models
Pourbaix, D.
From the published visual and spectroscopic observations together with some unpublished radial velocities kindly provided by R.F. Griffin, we determine an orbit which accurately reproduces the time of the primary eclipse observed by \cite*{Griffin-1994} and also recompute Hipparcos astrometric parameters. The orbital parallax is slightly off with …
Hipparcos catalogue orientation as obtained from observations of minor planets
Chernetenko, Yu. A.; Batrakov, Yu. V.; Gorel, G. K. +1 more
Ground-based photographic observations of 12 minor planets obtained at Nikolaev observatory (Ukraine) between 1961-1995 were reduced to the Hipparcos catalogue system and processed by the least squares method (LSM) separately and in combination with the Hipparcos NDAC (the Northern Data Analysis Consortium) and FAST (the Fundamental Astronomy by S…
Identification of absorbing galaxies towards the QSO J2233-606 in the Hubble Deep Field South
Tresse, Laurence; Petitjean, Patrick; Cristiani, Stefano +2 more
We present spectroscopic observations of galaxies lying within 1' of QSO J2233-606 in the Hubble Deep Field South (HDF-S). Several are found to be coincident in redshift with absorption-line systems seen in the HST J2233-606 spectrum. We detect a new z_em = 1.336 QSO with I = 20.8 at a projected angular separation of 44.5'' (or rho = 200h(-1) kpc;…
Power spectra comparison between GOLF and spatially masked MDI velocity signals
Henney, C. J.; Scherrer, P. H.; Turck-Chièze, S. +5 more
The Global Oscillations at Low Frequency (GOLF) and the Michelson Doppler Imager (MDI) instruments aboard the Solar and Heliospheric Observatory (SOHO) give an excellent opportunity to search for solar low frequency oscillation modes previously undetected from ground based experiments. Presented here is a comparison of the velocity power spectra b…
Atomic fine-structure lines in the ISO-SWS spectra of the supergiants alpha Orionis and alpha Scorpii
Waters, L. B. F. M.; Justtanont, K.; Tielens, A. G. G. M. +3 more
We report the detection of infrared fine-structure lines of [Fe II] and [Si II] in the ISO-SWS spectra of two supergiants, alpha Ori and alpha Sco. From the observed intensities we infer that the emitting regions have temperatures in the range 1200-1800 K and are located within about 20 R_{*} from the star. This is interior to the region where dus…
V2109 Cygni, a second overtone field RR Lyrae star
Thomson, J. R.; Kiss, L. L.; Csák, B. +1 more
We present the first (as of February, 1999) UBV and uvby photometric measurements for the short period variable star V2109 Cyg discovered by the Hipparcos satellite and classified as a field RRc variable. We have obtained new times of maxima and the period change has been studied. We determined the fundamental physical parameters using the geometr…
Damping and frequency reduction of the f-mode due to turbulent motion in the solar convection zone
Murawski, K.; Mȩdrek, M.; Roberts, B.
Solar f-mode properties were observed recently with high accuracy using high-resolution Michelson Doppler Imager (MDI) data from SOHO (Duvall et al. 1998). According to these observations, linewidths increase with wavenumber k and the f-mode frequency omega is significantly lower than the frequency omega_0 given by the simple dispersion relation o…
Starburst nuclei: ISO observations and models
Siebenmorgen, R.; Krügel, E.; Zota, V.
1.) We present photometric data of three starburst galaxies (Mkn 496, Mkn 1116, NGC 6000) obtained with the Infrared Space Observatory (ISO) in the wavelength bands 2.5-11.6 mu m (P-40) and 120-200 mu m (P-22). In all galaxies, we detect the 9.7 mu m silicate absorption feature and strong emission from PAHs; only the 3.3 mu m band is below the sen…