Search Publications
An X-Ray Investigation of the NGC 346 Field in the Small Magellanic Cloud I. The Luminous Blue Variable HD 5980 and the NGC 346 Cluster
Koenigsberger, G.; Corcoran, M. F.; Nazé, Y. +5 more
We present results from a Chandra observation of the NGC 346 cluster. This cluster contains numerous massive stars and is responsible for the ionization of N66, the most luminous H II region and the largest star formation region in the SMC. In this first paper we will focus on the characteristics of the main objects of the field. The NGC 346 clust…
Far-Infrared OH Fluorescent Emission in Sagittarius B2
Cernicharo, José; Goicoechea, Javier R.
We present Infrared Space Observatory (ISO) observations of 16OH and 18OH toward Sgr B2 with a spectral resolution of ~35 km s-1. The OH J=5/2-->3/2 and J=3/2-->1/2 rotational lines of the 2Π1/2 ladder are seen in emission, while the cross-ladder transitions (from the 2Π3…
A Young Very Low Mass Object Surrounded by Warm Dust
Testi, L.; D'Antona, F.; Comoretto, G. +5 more
We present a complete low-resolution (R~100) near-IR spectrum of the substellar object GY11, a member of the ρ Ophiuchi young association. The object is remarkable because of its low estimated mass and age and because it is associated with a mid-IR source, an indication of a surrounding dusty disk. Based on the comparison of our spectrum with simi…
Detailed Spectroscopic Analysis of SN 1987A: The Distance to the Large Magellanic Cloud Using the Spectral-fitting Expanding Atmosphere Method
Pun, Chun S. J.; Baron, E.; Lundqvist, Peter +5 more
Supernova 1987A remains the most well studied supernova to date. Observations produced excellent broadband photometric and spectroscopic coverage over a wide wavelength range at all epochs. We model the observed spectra from day 1 to day 81 using a hydrodynamical model. We show that good agreement can be obtained at times up to about 60 days if we…
Limits on the Mass of the Central Black Hole in 16 Nearby Bulges
Filippenko, Alexei V.; Ho, Luis C.; Shields, Joseph C. +6 more
We report upper limits on the masses of black holes that can be present in the centers of 16 nearby galaxy bulges. These limits MlimBH for our statistically complete sample were derived from the modeling of the central emission-line widths ([N II] or [S II]), observed over a 0.25"×0.2" (R<~9 pc) aperture. The experiment ha…
Evolution and Geometry of Hot Spots in Supernova Remnant 1987A
Crotts, Arlin P. S.; Lawrence, Stephen S.; Sugerman, Ben E. K. +2 more
We present ground-based near-infrared imaging and Hubble Space Telescope optical imaging and spectroscopy of the interaction between the ejecta of SN 1987A and its equatorial circumstellar ring. This interaction has made a transition, from emission originating in just a few ``hot spots'' at restricted locations in position angle around the ring, t…
Observations of T Tauri Stars Using the Hubble Space Telescope GHRS. II. Optical and Near-Ultraviolet Lines
Valenti, Jeff A.; Walter, Frederick M.; Ardila, David R. +2 more
We have analyzed GHRS data of eight classical T Tauri stars (CTTSs) and one weak T Tauri star (WTTS). The GHRS data consist of a spectral range 40 Å wide centered on 2800 Å. For four of the CTTSs, we have nearly simultaneous optical observations that contain Hα, Hβ, He I, Na D, and the Ca II infrared triplet. The Mg II resonance doublet is the str…
Two Subclasses of Proto-Planetary Nebulae: Model Calculations
Ueta, Toshiya; Meixner, Margaret; Bobrowsky, Matthew +1 more
We use detailed radiative transfer models to investigate the differences between the star-obvious low-level elongated proto-planetary nebulae (SOLE PPNs) and dust-prominent longitudinally extended proto-planetary nebulae (DUPLEX PPNs), which are two subclasses of PPNs suggested by Ueta, Meixner, & Bobrowsky. We select one SOLE PPN, HD 161796, …
Infrared Fe II Emission in Narrow-Line Seyfert 1 Galaxies
Pastoriza, M. G.; Prato, L.; Rodríguez-Ardila, A. +1 more
We obtained 0.8-2.4 µm spectra at a resolution of 320 km s-1 of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the Fe II emission in that region and the kinematics of the low-ionization broad lines. We show that the 1 µm Fe II lines (λ9997, λ10…
A Far Ultraviolet Spectroscopic Explorer Survey of Interstellar O VI Absorption in the Small Magellanic Cloud
Hoopes, Charles G.; Sembach, Kenneth R.; Savage, Blair D. +2 more
We present the results of a Far Ultraviolet Spectroscopic Explorer (FUSE) survey of O VI λ1031.93 and λ1037.62 absorption toward 18 OB stars in the Small Magellanic Cloud (SMC). The FUSE data are of very high quality, allowing a detailed study of the coronal temperature gas in the SMC. We find that O VI is ubiquitous in the SMC, with a detection a…