Search Publications
The EC14026 stars - VI. PG1047+003
O'Donoghue, D.; Kilkenny, D.; Lynas-Gray, A. E. +2 more
We report the discovery of rapid oscillations in the sdB star PG1047+003. The oscillations are multiperiodic, with nine periods in the range 104-162s. The optical spectrum of PG1047+003 is consistent with that of a single sdB star. Line profile fitting yields an effective temperature of 35000+/-1000K and log g=5.9+/-0.1, although optical photometr…
Near-Infrared Observations of a Redshift 4.92 Galaxy: Evidence for Significant Dust Absorption
Illingworth, G. D.; Franx, M.; Matthews, K. +2 more
Near-infrared imaging and spectroscopy have been obtained of the gravitationally lensed galaxy at z=4.92 discovered in Hubble Space Telescope (HST) images by Franx et al. Images at 1.2, 1.6, and 2.2 µm show the same arc morphology as the HST images. The spectrum with resolution λ/Δλ~70 shows no emission lines with equivalent width stronger t…
Lensing galaxies: light or dark?
Fassnacht, C. D.; Jackson, N.; Wilkinson, P. N. +4 more
In a recent paper, Hawkins (1997) argues on the basis of statistical studies of double-image gravitational lenses and lens candidates that a large population of dark lenses exists and that these outnumber galaxies with more normal mass-to-light ratios by a factor of 3:1. If correct, this is a very important result for many areas of astronomy inclu…
A Brief History of Recurrent Solar Modulation of the Galactic Cosmic Rays (1937-1990)
Simpson, J. A.
This brief review of the pre-Ulysses era begins with the first measurements by ionization chambers in 1937 of a cosmic ray 27-day intensity variation that was believed to have its origin in recurrent variations of the geomagnetic field. However, with the introduction of neutron monitor analysis of the nucleonic component, it was shown in the 1940s…
A Reanalysis of the Carbon Abundance in the Translucent Cloud Toward HD 24534
Sofia, Ulysses J.; Fitzpatrick, Edward L.; Meyer, David M.
We have reanalyzed the Goddard High Resolution Spectrograph data set presented by Snow et al., which contains the interstellar intersystem C II] λ2325 line through the translucent cloud toward HD 24534 (X Persei). In contrast to the results of Snow et al., we clearly detect the C II] feature at the 3 σ confidence level and measure a C+ …
Spectral analysis of the extreme helium star LSS3184
Heber, U.; Drilling, J. S.; Jeffery, C. S.
LSS3184 is a hydrogen-deficient, early B-type giant, recently found to pulsate with a period of 2.5 hours. Its photospheric parameters have been derived from optical high-resolution spectra by the method of fine analysis. The principal results are T_eff=23300 K, log g=3.35, {n_H}/{n_He}simle0.00015, {n_C}/{n_He}=0.003, {n_N}/{n_He}=0.0005, and {n_…
Fractionation of SI, NE, and MG Isotopes in the Solar Wind as Measured by Soho/Celias/MTOF
Bochsler, P.; Geiss, J.; Galvin, A. B. +9 more
Using the high-resolution mass spectrometer CELIAS/MTOF on board SOHO we have measured the solar wind isotope abundance ratios of Si, Ne, and Mg and their variations in different solar wind regimes with bulk velocities ranging from 330 km/s to 650 km/s. Data indicate a small systematic depletion of the heavier isotopes in the slow solar wind on th…
HST - GHRS observations of CO and CI fill in the beta -Pictoris circumstellar disk
Feldman, P. D.; Ferlet, R.; Jolly, A. +7 more
GHRS-EchA and G160M spectra of beta -Pictoris have been obtained in the 1400-1600 Angstroms range. A detailed analysis of the CO A-X (0-0, 1-0, 2-0) bands and of the CI lambda 1561 Angstroms multiplet is presented. A column density of the order of 2 10(15) cm(-2) is found for both species. For CO, the rotational temperature is found close to 20 K …
A Multiwavelength Campaign on γ Cassiopeiae. II. The Case for Corotating, Circumstellar Clouds
Smith, Myron A.; Robinson, Richard D.; Hatzes, Artie P.
Simultaneous X-ray/UV observations over a full day on 1996 March 14-15 have been made of the prototypical B0.5e star γ Cas using the Rossi X-Ray Timing Explorer satellite and the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. The GHRS spectra, taken in the region of the Si IV λλ1394-1403 doublet, also permitted th…
BVI CCD Photometry of the Globular Cluster 47Tuc
Stanek, K. Z.; Kaluzny, J.; Krzeminski, W. +1 more
We present BVI photometry for about 16000 stars from a 220 square arcmin field centered 8arcmin East of the center of 47 Tuc. We have identified eight likely blue stragglers located in the outer parts of the cluster. Four of these objects are easy targets for spectroscopic studies with ground-based telescopes. Six candidates for blue horizontal br…