Search Publications
HD 42927 and HD 126341: two pulsating B stars surrounded by circumstellar dust
Aerts, C.; De Cat, P.; Malfait, K. +1 more
We have performed an infrared study of pulsating B stars. The main conclusion is that none of the 163 (non-)radial pulsators shows an IR excess flux due to free-free emission, despite the fact that the sample contains several rapid rotators. Two beta Cep stars and two slowly pulsating B stars do exhibit an unexpected infrared colour excess at 12 m…
CCD astrometry of faint compact extragalactic radio sources . I. First results and description of the program
Costa, E.; Loyola, P.
Optical positions relative to the Hipparcos Catalogue (ESA 1997) have been obtained for the optical counterparts of 15 faint (B ~ 20-23) southern compact extragalactic radio sources (CERS). Most of these sources are not adequately observable (or simply not visible) by means of direct photography with a conventional wide-field telescope, so the pos…
Hubble Space Telescope Observations of the Serendipitous X-Ray Companion to Markarian 273: Cluster at z=0.46?
Lucas, Ray A.; Colina, Luis; Bushouse, Howard +1 more
We have used Hubble Space Telescope (HST) I-band images to identify Mrk 273X, the very unusual high-redshift X-ray-luminous Seyfert 2 galaxy found by ROSAT in the same field of view as Mrk 273. We have measured the photometric properties of Mrk 273X and have also analyzed the luminosity distribution of the faint galaxy population seen in the HST i…
The kinematics of RR Lyrae stars observed by HIPPARCOS
Chen, B.
We discuss the distributions of velocities and metallicities for 144 RR Lyrae stars observed by the Hipparcos astrometry satellite. The new absolute magnitude calibration of RR Lyrae stars and an all-sky reddening map have been used to derive individual distances accurately. Three statistical analysis techniques based on pattern recognition theory…
Changes and Absorption Features in the Ultraviolet Spectrum of the PG 1159-Type Central Star RX J2117+3412
Feibelman, Walter A.
Comparison of IUE high- and low-dispersion spectra for the PG 1159-type central star of RX J2117+3412 indicates that the stellar continuum level and some absorption features decreased between 1993 and 1995. These observed changes may represent a new phenomenon not previously known to occur in PG 1159-type DO degenerates. The definite detection of …
ISO far-infrared observations of rich galaxy clusters. I. Abell 2670
Nørgaard-Nielsen, H. U.; Pedersen, K.; Hansen, L. +3 more
As part of an investigation of far-infrared emission from rich galaxy clusters the central part of Abell 2670 has been mapped with ISO at 60 mu m, 100 mu m, 135 mu m, and 200 mu m using the PHT-C camera. Point sources detected in the field have infrared fluxes comparable to normal spirals at the cluster distance. Probable optical counterparts are …
Far-Ultraviolet Imaging of the Field Star Population in the Large Magellanic Cloud with the Hubble Space Telescope
Brosch, Noah; Zurek, David; MacKenty, John +2 more
We present an analysis of the deepest pure UV observations with the highest angular resolution ever performed, a set of 12 exposures with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and F160BW filter obtained in parallel observing mode, which covers ~12 arcmin^2 in the Large Magellanic Cloud (LMC), north of the bar, and in the `…
Two-fluid 2.5D MHD Simulations of the Fast Solar Wind in Coronal Holes and the Relation to UVCS Observations
Davila, J. M.; Ofman, L.
Recent SOHO/UVCS observations indicate that the perpendicular proton and ion temperatures are much larger than electron temperatures. In the present study we simulate numerically the solar wind flow in a coronal hole with the two-fluid approach. We investigate the effects of electron and proton temperatures on the solar wind acceleration by nonlin…
Interplanetary scattering effects in the jovian bKOM radio emission observed by ULYSSES
MacDowall, R. J.; Woan, G.; Barrow, C. H.
The scattering of radio waves by the interplanetary medium (subsequently referred to simply as `scattering') imposes limitations on measurements of fine temporal and angular structure at low radio frequencies. The jovian broad-band kilometric radiation (bKOM) is highly structured and observations of this emission, by the Unified Radio and Plasma E…
Hubble Space Telescope Imaging Polarimetry of the Gravitational Lens FSC 10214+4724
Hogg, David W.; Eisenhardt, Peter R.; Soifer, B. T. +5 more
We present imaging polarimetry of the extremely luminous, redshift 2.3 IRAS source FSC 10214+4724. The observations were obtained with HST's Faint Object Camera in the F437M filter, which is free of strong emission lines. The 0.7" long arc is unresolved to 0.04" FWHM in the transverse direction and has an integrated polarization of 28%+/-3%, in go…