Search Publications
The WR+OB Progenitor RY Scuti: Intensive Spectroscopy of Its Compact Double-Ring Nebula
Smith, Nathan; Gehrz, Robert D.; Balick, Bruce +2 more
We present a detailed spectroscopic analysis of the peculiar nebula around RY Scuti using data from the Space Telescope Imaging Spectrograph (STIS) and various ground-based observatories. This massive contact binary may represent a rapid evolutionary phase in transition to a short-period WR+OB system, and it is surrounded by a young nebula with un…
Faint Cataclysmic Variables in Quiescence: Globular Cluster and Field Surveys
Bildsten, Lars; Townsley, Dean M.
Current evolutionary models imply that most cataclysmic variables (CVs) have Porb<2 hr and are dwarf nova (DN) systems that are quiescent most of the time. Observations of nearby quiescent DNs find that the UV spectrum is dominated by the hot white dwarf (WD), indicating that it provides a significant fraction of the optical light in…
GRB 010921: Discovery of the First High Energy Transient Explorer Afterglow
Price, P. A.; Harrison, F. A.; Reichart, D. E. +16 more
We report the discovery of the optical and radio afterglow of GRB 010921, the first gamma-ray burst afterglow to be found from a localization by the High Energy Transient Explorer satellite. We present optical spectroscopy of the host galaxy, which we find to be a dusty and apparently normal star-forming galaxy at z=0.451. The unusually steep opti…
High-Dispersion Spectroscopy of the X-Ray Transient RXTE J0421+560 (=CI Camelopardalis) during Outburst
Welsh, William F.; Ivans, Inese I.; Robinson, Edward L.
We obtained high-dispersion spectroscopy of CI Cam, the optical counterpart of XTE J0421+560, 2 weeks after the peak of its short outburst in 1998 April. The optical counterpart is a supergiant B[e] star that is emitting a two-component wind, a cool, low-velocity wind and a hot, high-velocity wind. The cool wind, which is the source of narrow emis…
Nobeyama Millimeter Array CO (J=1-0) Observations of the Hα/Radio Lobe Galaxy NGC 3079: Gas Dynamics in a Weak Bar Potential and Central Massive Core
Kohno, K.; Koda, J.; Sofue, Y. +4 more
We present 12CO (1-0) observations in the central 4.5 kpc (1') of the Hα/radio lobe galaxy NGC 3079 with the Nobeyama Millimeter Array. The molecular gas shows four components: a main disk, spiral arms, a nuclear disk, and a nuclear core. The main disk extends along the galaxy major axis. We detected its central 2 kpc radius, while its …
Cosmic Alignment toward the Radio Einstein Ring PKS 1830-211?
Kneib, J. -P.; Lidman, C.; Meylan, G. +1 more
Optical and near-IR Hubble Space Telescope and Gemini North adaptive optics images, further improved through deconvolution, are used to explore the gravitationally lensed radio source PKS 1830-211. The line of sight to the quasar at z=2.507 appears to be very busy, with the presence, within 0.5" from the source, of (1) a possible galactic main-seq…
Hubble Space Telescope/WFPC2 Images of the GG Tauri Circumbinary Disk
Krist, John E.; Stapelfeldt, Karl R.; Watson, Alan M.
We present the first visible wavelength images of the GG Tau circumbinary ring obtained with the Hubble Space Telescope's (HST) Wide Field and Planetary Camera 2. Scattered light from the ring is detected in both V- and I-band images. The images show that the ring is smooth, except for a small gap that could be a shadow caused by material between …
Energy Transformation Mechanism in the Solar Atmosphere Associated with Magnetofluid Coupling: Explosive and Eruptive Events
Ohsaki, Shuichi; Shatashvili, Nana L.; Yoshida, Zensho +1 more
By modeling the closed field structures in the solar atmosphere by ``slowly'' evolving double Beltrami two-fluid equilibria (created by the interaction of the magnetic and velocity fields), the conditions for catastrophic transformations of the original state are derived. The analysis for predicting sudden changes is carried out through a set of a…
The Next Geminga: Deep Multiwavelength Observations of a Neutron Star Identified with 3EG J1835+5918
Mirabal, N.; Camilo, F.; Gotthelf, E. V. +1 more
We describe Chandra, Hubble Space Telescope (HST), and radio observations that reveal a radio-quiet but magnetospherically active neutron star in the error circle of the high-energy γ-ray source 3EG J1835+5918, the brightest of the unidentified EGRET sources at high Galactic latitude. A Chandra ACIS-S spectrum of the ultrasoft X-ray source RX J183…
The Origin of Fe II and [Fe II] Emission Lines in the 4000-10000 Å Range in the BD Weigelt Blobs of η Carinae
Davidson, K.; Gull, T. R.; Bruhweiler, F. +3 more
We present numerical simulations that reproduce the salient features of the amazingly strong [Fe II] and Fe II emission spectra in the B and D Weigelt blobs of η Carinae. For our studies we have used spectra obtained during the 1998 epoch observations with the Hubble Space Telescope (HST). The spectrum of the B and D Weigelt blobs dominates in [Fe…