Search Publications
The Mass Accretion Rates of Intermediate-Mass T Tauri Stars
Gordon, Karl D.; Hartmann, Lee; Calvet, Nuria +4 more
We present Hubble Space Telescope ultraviolet spectra and supporting ground-based data for a sample of nine intermediate-mass T Tauri stars (IMTTSs; 1.5-4 Msolar). The targets belong to three star-forming regions: T Tau, SU Aur, and RY Tau in the Taurus clouds; EZ Ori, P2441, and V1044 Ori in the Ori OB1c association surrounding the Ori…
Hubble Space Telescope Absolute Spectrophotometry of Vega from the Far-Ultraviolet to the Infrared
Bohlin, R. C.; Gilliland, R. L.
The Space Telescope Imaging Spectrograph (STIS) has measured the absolute flux for Vega from 0.17-1.01 µm on the Hubble Space Telescope white dwarf (WD) flux scale. These data are saturated by up to a factor of 80 overexposure but retain linearity to a precision of 0.2% because the charge bleeds along the columns and is recovered during read…
Markarian 1239: A Highly Polarized Narrow-Line Seyfert 1 Galaxy with a Steep X-Ray Spectrum and Strong Ne IX Emission
Komossa, S.; Grupe, D.; Mathur, S.
We report the results of an XMM-Newton observation of the narrow-line Seyfert 1 galaxy Mrk 1239. This optically highly polarized AGN has one of the steepest X-ray spectra found in AGNs, with αX=+3.0 based on ROSAT PSPC data. The XMM-Newton EPIC pn and MOS data confirm this steep X-ray spectrum. The pn data are best fitted by a power law…
Barnard's Star and the M Dwarf Temperature Scale
De Robertis, M. M.; Dawson, P. C.
The recently measured angular diameter of Barnard's star, together with its large and precise parallax, and a spectral energy distribution that extends from the near-ultraviolet to almost 12 µm establish some of the star's fundamental properties-we find a bolometric luminosity L=(3.46+/-0.17)×10-3Lsolar, radius R=0.200+…
Far Ultraviolet Spectroscopic Explorer Spectroscopy of Absorption and Emission Lines from the Narrow-Line Seyfert 1 Galaxy NGC 4051
Brandt, W. N.; Kaspi, Shai; Elvis, Martin +2 more
We present three Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the narrow-line Seyfert 1 galaxy NGC 4051. The most prominent features in the far-ultraviolet (FUV) spectrum are the O VI emission and absorption lines and the H I Lyman series absorption lines, which are detected up to the Lyman edge. We also identify weak emission fro…
New and Confirmed Triple Systems with Luminous Cool Primaries and Hot Companions
Parsons, Sidney B.
In the course of comparing parameters of evolved cool star plus hot main-sequence star binaries with theoretical isochrones, some discrepancies are found between implied stellar masses and the spectroscopic binary mass function or the measured angular separation. These are naturally explained if there is a third star in the system. Multiplicity is…
Synthetic Spectral Analysis of the Hot Component in the S-Type Symbiotic Variable EG Andromedae
Sion, Edward M.; Mikołajewska, Joanna; Kolb, Kelly +1 more
We have applied grids of non-LTE (NLTE) high-gravity model atmospheres and optically thick accretion disk models for the first time to archival IUE and FUSE spectra of the S-type symbiotic variable EG Andromedae taken at superior spectroscopic conjunction, when Rayleigh scattering should be minimal and the hot component is viewed in front of the r…