Search Publications
The Interstellar Boron Abundance toward Orion
Meyer, David M.; Jura, M.; Cardelli, Jason A. +1 more
We have used the Goddard High-Resolution Spectrograph to measure the abundance of interstellar boron in several low-density sight lines toward Orion. In particular, we detected the B II 1362 Å line toward λ Ori with an equivalent width (1.0±0.3 mÅ) that implies a B/H abundance ratio (9.1 × 10-11) equal, within the errors, to that found …
Multiwavelength Observations of Two Moderate Rotation RS CVn Systems: V815 Herculis and IM Pegasi
Neff, James E.; Dempsey, Robert C.; O'Neal, Douglas +1 more
Near-to-simultaneous ultraviolet and visual spectroscopy of two moderate v sin i RS CVn systems, V815 Herculis (v sin i=27 km s-1) and IM Pegasi (v sin i=24 km s-1), are presented along with contemporaneous UBV(RI)c photometry. These data were used to probe inhomogeneities in the chromospheres and photospheres, and the possib…
Unusual Comets (?) as Observed from the Hubble Space Telescope
Weaver, Harold A.; Meech, Karen J.
In separate projects, the Hubble Space Telescope has been used to assess the nature of 3 unusual objects: Chiron, Pholus and P/Shoemaker-Levy 9. This paper will compare these objects and discuss how the unique capabilities of the HST may be used to address the issue of cometary activity in each. Chiron, which has exhibited obvious cometary charact…
ULYSSES COSPIN/LET: latitudinal gradients of anomalous cosmic ray O, N and Ne.
Klecker, B.; Bothmer, V.; Sanderson, T. R. +4 more
A key goal of the Ulysses mission is the measurement of the latitudinal gradient of the Anomalous Cosmic Ray (ACR) component. Earlier studies using data from the COSPIN/LET experiment on board Ulysses together with in-ecliptic data from the HILT instrument on SAMPEX have shown a small (~2% per degree) positive latitudinal gradient for anomalous ox…
Is 2RE J0357+283 the most coronally active star in the Galaxy?
Jeffries, R. D.; Burleigh, M. R.; Robb, R. M.
The late-type stellar counterpart to the EUV source 2RE J0357+283 is found to be an ultra-fast rotating K2V star, with a rotation period of 8.76 hrs and vsini of 141+/-5km/s. If this were the only source of the EUV emission, then it would be the most coronally active star known, by an order of magnitude, and requires a reappraisal of current ideas…
Dynamic Processes in Be Star Atmospheres. IV. Common Attributes of Line Profile ``Dimples''
Smith, Myron A.; Thomson, J. R.; Basri, G. S. +3 more
"Dimples" are transient central absorption features flanked by weak emissions commonly seen in the He I λ6678 line profile of the mild B2e star λ Eridani. Smith & Polidan have found that these features can be reproduced with a model in which line photons are scattered within an optically thick (in the line) slab elevated over the surface of a …
The Contribution of Asteroid Dust to the Interplanetary Dust Cloud: The Impact of ULYSSES Results on the Understanding of Dust Production in the Asteroid Belt and of the Formation of the IRAS Dust Bands
Mann, Ingrid; Grün, Eberhard; Wilck, Martin
Investigations of the zodiacal dust cloud give evidence for a significant contribution of asteroidal dust to the interplanetary dust cloud, a result which can now be compared to measurements of the ULYSSES dust detector during its passage of the asteroid belt. Especially we discuss the ULYSSES data with respect to the IRAS dust bands and consider …
ROSAT X-Ray Observations of Four Planetary Nebulae
Kwok, Sun; Leahy, D. A.; Volk, K. +1 more
We report ROSAT Position Sensitive Proportional Counter (PSPC) observations of four planetary nebulae. The observations show that all four nebulae have two-component spectra. A two-component model consisting of a blackbody and a Raymond-Smith thermal plasma is fitted to the observed ROSAT PSPC spectra of NGC t535, Abell 36, and NGC 7293. For all t…
The Accretion Disk (Belt?) During the Quiescence of VW Hydri
Szkody, P.; Sion, E. M.; Huang, M. +2 more
We considered the contribution of an accretion disk to the UV spectrum of the dwarf nova (DN) VW Hydri during its quiescence, obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). Our analysis indicates that the UV emitting area of the disk is a ring of width 0.06 RWD, inclination angle i=60°, rotating w…
First results from a photometric infrared survey for Vega-like disks around nearby main-sequence stars.
Waters, L. B. F. M.; Kessler, M. F.; Siebenmorgen, R. +12 more
We have undertaken a survey for Vega-like disks around nearby main-sequence stars by making photometric measurements with ISOPHOT at four wavelengths between 25 and 180µm. Our goal is to establish how common Vega-like disks are, and how their presence depends on the fundamental properties of main-sequence stars (mass, age, rotation etc.). He…