Search Publications
Boron Abundances in Early B Stars: Results from the B III Resonance Line in IUE Data
Proffitt, Charles R.; Quigley, Mark F.
We have used archival International Ultraviolet Explorer high-dispersion SWP spectra to study the B III resonance line at 2065.8 Å in 44 early B stars. We find a median boron abundance about half that of solar system meteoritic material, consistent with the values found from previous studies of boron in early B stars. About one-third of the stars …
Constraining the Black Hole Mass and Accretion Rate in the Narrow-Line Seyfert 1 Galaxy RE J1034+396
Fiore, F.; Comastri, A.; Siemiginowska, A. +4 more
We present a comprehensive study of the spectrum of the narrow-line Seyfert 1 (NLS1) galaxy RE J1034+396, summarizing the information obtained from the optical to X-rays with observations from the William Herschel 4.2 m Telescope, the Hubble Space Telescope, the Extreme Ultraviolet Explorer, ROSAT, ASCA, and BeppoSAX. The BeppoSAX spectra reveal a…
An Observational Manifestation of Magnetoatmospheric Waves in Internetwork Regions of the Chromosphere and Transition Region
Peter, H.; Judge, P. G.; Cally, P. S. +7 more
We discuss an observational signature of magnetoatmospheric waves in the chromosphere and transition region away from network magnetic fields. We demonstrate that when the observed quantity, line or continuum emission, is formed under high-β conditions, where β is the ratio of the plasma and magnetic pressures, we see fluctuations in intensity and…
New Constraints on Protostellar Jet Collimation from High-Density Gas UV Tracers
Gómez de Castro, Ana I.; Verdugo, Eva
The analysis of high-resolution profiles of the semiforbidden UV lines of C III]1908 and Si III]1892 in the spectra of T Tauri stars (TTSs) shows the following: (1) There is C III]1908 and Si III]1892 emission at velocities that are similar to those observed in the optical forbidden lines formed in the T…
High-Resolution Spectroscopic Observations of Hipparcos Red Clump Giants: Metallicity and Mass Determinations
Zhao, G.; Mao, Shude; Qiu, H. M.
We obtain high-resolution and high signal-to-noise ratio spectra of 39 red clump giants selected from the Hipparcos Catalogue. We determine their atmospheric parameters, iron abundances, α-element enhancements, and masses. We find that the sample can be divided into a metal-poor group and a metal-rich group. The majority of the stars are metal-ric…
K-Band Spectroscopy of Compact Star Clusters in NGC 4038/4039
Lehnert, Matthew D.; Genzel, Reinhard; Thatte, Niranjan +2 more
Integral field spectroscopy in the K band (1.9-2.4 µm) was performed on four IR-bright star clusters and the two nuclei in NGC 4038/4039 (``the Antennae''). Two of the clusters are located in the overlap region of the two galaxies and together comprise ~25% of the total 15 µm emission of the total 4.8 GHz emission from this pair of mer…
IRAS 11590-6452 in BHR 71: A Binary Protostellar System?
Bourke, Tyler L.
New Anglo-Australian Telescope near-infrared and Swedish-ESO Submillimetre Telescope 12CO J=2-->1 observations are combined with existing Infrared Space Observatory mid-infrared and Australia Telescope Compact Array centimeter radio continuum observations to examine the protostellar content of the Bok globule BHR 71. Together with ob…
Spatially Resolved STIS Spectroscopy of α Orionis: Evidence for Nonradial Chromospheric Oscillation from Detailed Modeling
Lobel, A.; Dupree, A. K.
Four spatially resolved near-UV raster scans across the chromospheric disk of α Ori, obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, reveal mean chromospheric infall from 1998 January to April, which reversed to upflow in deeper layers between 1998 September and 1999 March. In 1998 September we detect systemat…
Hubble Space Telescope Observations of SGR 0526-66: New Constraints on Accretion and Magnetar Models
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaplan, D. L. +5 more
Soft γ-ray repeaters (SGRs) are among the most enigmatic sources known today. Exhibiting huge X-ray and γ-ray bursts and flares, as well as soft quiescent X-ray emission, their energy source remains a mystery. Just as mysterious are the anomalous X-ray pulsars (AXPs), which share many of the same characteristics. Thanks to recent Chandra X-Ray Obs…
Cold H2O and CO Ice and Gas toward the Galactic Center
Cernicharo, José; Moneti, Andrea; Pardo, Juan Ramón
We present ice- and gas-phase observations of CO, 13CO and of H2O in the mid- and far-infrared taken with the Infrared Space Observatory (ISO) short- and long-wavelength spectrometers toward two positions in the Galactic center region (Sagittarius A* and GCS 3). These data are complemented with Caltech Submillimeter Observato…