Search Publications
Detection of H2 Emission from Mira B in Ultraviolet Spectra from the Hubble Space Telescope
Wood, Brian E.; Karovska, Margarita; Hack, Warren
We present ultraviolet spectra of Mira's companion star from the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). The companion is generally assumed to be a white dwarf surrounded by an accretion disk fed by Mira's wind, which dominates the UV emission from the system. The STIS UV spectrum is domina…
The Physics of the Solar Lower Transition Region
Doschek, G. A.; Mariska, J. T.
We discuss quiet-Sun intensities of spectral lines of O IV λ1401.16 and Si IV λ1402.77, their ratio, and their relation to expected properties of the lower solar transition region. The data consist of simultaneous measurements of the two line intensities for 16,988 pixels with spatial dimensions of 1" square obtained by the Solar Ultraviolet Measu…
A Critical Examination of Hypernova Remnant Candidates in M101. I. MF 83
Grebel, Eva K.; Lai, Shih-Ping; Ciardullo, Robin +2 more
The supernova remnant (SNR) candidate MF 83 in M101 is coincident with a very luminous X-ray source. Based on the high X-ray luminosity, it has been suggested that MF 83 is a ``hypernova remnant'' requiring an explosion energy about 2 orders of magnitude higher than normal supernovae. We have analyzed high-quality ground-based and Hubble Space Tel…
Preprotostellar Core Properties from Far-Infrared Observations
Langer, W. D.; Willacy, K.
We present the results of far-infrared ISOPHOT observations of the preprotostellar cores L1498, B133, and B68. Comparison of the 100 and 200 µm data suggest the presence of two dust temperatures along the line of sight. Using a two-temperature model that assumes a cold central core surrounded by a slightly warmer envelope, we have isolated t…
A Cepheid is No More: Hubble's Variable 19 in M33
Stanek, K. Z.; Macri, L. M.; Sasselov, D. D.
We report on the remarkable evolution in the light curve of a variable star discovered by Hubble in M33 and classified by him as a Cepheid. Early in the 20th century, the variable, designated as V19, exhibited a 54.7 day period, an intensity-weighted mean B magnitude of 19.59+/-0.23 mag, and a B amplitude of 1.1 mag. Its position in the period-lum…
Terminal Speeds and Ion Fractions from [Ca IV] 3.207 µm in Three Single WN Stars
Ignace, R.; Cassinelli, J. P.; Babler, B. +1 more
We report on the forbidden emission lines of [Ca IV] at 3.207 µm and [Ne III] at 15.56 µm based on Infrared Space Observatory observations. The data set consists of three single Wolf-Rayet stars (WR 1, WR 134, and WR 136) and three binary systems (WR 11, WR 146, and WR 147). For the single stars, only the [Ca IV] line was observed. Our…
Testing Hydrodynamic Models of LMC X-4 with Ultraviolet and X-Ray Spectra
Boroson, Bram; Kallman, Timothy; Blondin, John M. +1 more
We compare the predictions of hydrodynamic models of the LMC X-4 X-ray binary system with observations of UV P Cygni lines with the Goddard High Resolution Spectrograph and Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The hydrodynamic model determines density and velocity fields of the stellar wind, wind-compressed disk, acc…
Detection of the Faint Companion in the Massive Binary HD 199579
Bolton, C. T.; Fullerton, A. W.; Gies, D. R. +14 more
We present new radial velocity data for the massive binary HD 199579 O6 V((f)) based upon spectra obtained from IUE, the Canada-France-Hawaii Telescope, KPNO, the David Dunlap Observatory, and the GSU Multiple-Telescope Telescope. We derive a revised period, P=48.5216+/-0.0015 days, and improved orbital elements that agree with the earlier element…
A Burst from the Direction of UZ Fornacis with XMM-Newton
Mukai, Koji; Still, Martin
The XMM-Newton pointing toward the magnetic cataclysmic variable UZ For finds the source to be a factor of greater than 103 fainter than previous EXOSAT and ROSAT observations. The source was not detected for the majority of a 22 ks exposure with the European Photon Imaging Cameras, suggesting that the accretion rate either decreased or…
X-Ray and Ultraviolet Orbital Phase Dependence in LMC X-3
Boyd, Patricia T.; Smale, Alan P.; Dolan, Joseph F.
The black hole binary LMC X-3 is known to be variable on timescales of days to years. We investigate X-ray and ultraviolet variability in the system as a function of the 1.7 day binary phase using a 6.4 day observation with the Rossi X-Ray Timing Explorer (RXTE) from 1998 December. An abrupt 14% flux decrease, lasting nearly an entire orbit, is fo…