Search Publications
Potential Variations in the Interstellar N I Abundance
Andersson, B. -G.; McCandliss, Stephan R.; Moos, H. Warren +1 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph observations of the weak interstellar N I λ1160 doublet toward 17 high-density sight lines [N(Htot)>=1021 cm-2]. When combined with published data, our results reveal variations in the fractional N I abundance showi…
Near-Infrared Adaptive Optics Imaging of the Embedded Cluster NGC 2024
Beck, Tracy L.; Close, L. M.; Simon, M.
We present the results of a high-resolution near-infrared adaptive optics survey of the young obscured star-forming region NGC 2024. Out of the total 73 stars detected in the adaptive optics survey of the cluster, we find three binaries and one triple. The resulting companion star fraction, 7%+/-3% in the separation range of 0.35"-2.3" (145-950 AU…
Solar Wind Effects on the Transport of 3-10 MeV Cosmic-Ray Electrons from Solar Minimum to Solar Maximum
Fichtner, H.; Ferreira, S. E. S.; Potgieter, M. S. +2 more
We investigate the effects on the transport of a few MeV (~7 MeV) Jovian and Galactic electrons for different solar wind speed scenarios applicable to different heliospheric conditions. A three-dimensional, steady state model is used based on numerically solving Parker's transport equation, including the Jovian electron source, to compare model co…
Origins of the Highly Ionized Gas along the Line of Sight toward HD 116852
Richter, Philipp; Sembach, Kenneth R.; Savage, Blair D. +5 more
We present Hubble Space Telescope Imaging Spectrograph (HST/STIS) and Far Ultraviolet Spectroscopic Explorer (FUSE) observations of high ion interstellar ultraviolet absorption along the sight line to HD 116852. At a distance of 4.8 kpc, HD 116852 is an O9 III star lying in the low Galactic halo, -1.3 kpc from the plane of the Galaxy in the direct…
Density and Temperature Measurements in a Solar Active Region
Winebarger, Amy R.; Warren, Harry P.
We present electron density and temperature measurements from an active region observed above the limb with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory. Density-sensitive line ratios from Si VIII and S X indicate densities greater than 108 cm-3 as high as 200"…
Dust in Hot Gas: Far-Infrared Emission from Three Local Elliptical Galaxies
Brighenti, Fabrizio; Mathews, William G.; Bregman, Jesse D. +1 more
We present far-IR Infrared Space Observatory observations of three early-type galaxies in the Virgo Cluster. The data were recorded using the ISOPHOT instrument in both the P32 oversampled maps and the P39/37 sparse maps. The maps reach the limiting sensitivity of the ISOPHOT instrument at 60, 90, and 180 µm. Two of the most prominent ellipt…
Dynamics of the Lyα and C IV Emitting Gas in 3C 273
Paltani, Stéphane; Türler, Marc
In this paper we study the variability properties of the Lyα and C IV emission lines in 3C 273 using archival International Ultraviolet Explorer observations. Our data show for the first time the existence of variability on timescales of several years. We study the spatial distribution and the velocity field of the emitting gas by performing detai…
Stellar Motions in the Polar Ring Galaxy NGC 4650A
Swaters, Rob A.; Rubin, Vera C.
We present the first measurement of the stellar kinematics in the polar ring of NGC 4650A. There is well-defined rotation, with the stars and gas rotating in the same direction, and with similar amplitude. The gaseous and stellar kinematics suggest an approximately flat rotation curve, providing further support for the hypothesis that the polar ma…
Near-Infrared Observations of BL Lacertae Host Galaxies
Giavalisco, Mauro; Cheung, C. C.; Urry, C. Megan +1 more
Multiband near-infrared images of 12 BL Lacertae objects were obtained with the 2.5 m telescope at the Las Campanas Observatory in order to determine the properties of their underlying host galaxies. Resolved emission was clearly detected in eight of the lowest redshift targets (up to z~0.3) and was modeled with a de Vaucouleurs r1/4 su…
Oxirane: An Exotic Oxygenated Organic Compound on Titan?
Raulin, François; Coll, Patrice; Bernard, Jean-Michel +1 more
After the discovery of CO, CO2, and more recently H2O in Titan's atmosphere, the chemistry of oxygenated organic compounds in this environment has been limited to theoretical studies only. Both kinetic and thermochemical models predict the formation of methanol and formaldehyde as the main O-organic products. Here we show tha…