Search Publications
First Results from the Space Telescope Imaging Spectrograph: Optical Spectra of Gliese 229B
Moos, H. W.; Bruhweiler, F. C.; Maran, S. P. +12 more
We report the first Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) CCD spectroscopy of the bona fide brown dwarf Gliese 229B. The optical spectrum shows absorptions of Cs I at 8944 Å and water vapor bands at 9300-9600 Å. Strong CaH, FeH, TiO, and VO bands observed in late M dwarfs are absent from the spectrum of Gliese 229B. Th…
Lyα Absorption Systems and the Nearby Galaxy Distribution
Grogin, Norman A.; Geller, Margaret J.
We study the galaxy number density (smoothed on a 5 h-1 Mpc scale) around 18 low-redshift Lyα absorbers previously observed with HST. The absorbers lie in the foregrounds of Mrk 335, Mrk 421, Mrk 501, I Zw 1, and 3C 273, all within regions where there are now complete redshift surveys to mZw = 15.5. We construct a smoothed ga…
Hubble Space Telescope Observations of the Gravitationally Lensed Cloverleaf Broad Absorption Line QSO H1413+1143: Spectroscopy of the Lyα Forest and Metal-Line Systems
Turnshek, David A.; Monier, Eric M.; Lupie, Olivia L.
The intervening Lyα forest and metal-line absorbers toward the ``Cloverleaf'' gravitational lens H1413+1143 (zem = 2.54, mv ~ 17) are examined along the four individual sight lines using HST-FOS spectra. The observations probe the Lyα forest systems on size scales of up to 4 h-1 kpc (H0 = 100 h km s…
Abundances of UV bright stars in globular clusters. I. ROA 5701 in omega Centauri and Barnard 29 in M 13
Heber, U.; Moehler, S.; Lemke, M. +1 more
Two UV brights stars in globular clusters, ROA 5701 (omega Cen) and Barnard 29 (M 13) are analysed from high-resolution UV and optical spectra. The main aim is the measurement of iron abundances from UV spectra obtained with the HST-GHRS. In addition atmospheric parameters and abundances for He, C, N, O, and Si are derived from optical spectra (ES…
New Hubble Space Telescope Observations of High-Velocity Lyα and Hα in SNR 1987A
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +12 more
We describe and model high-velocity (~15,000 km s-1) Lyα and Hα emission from the supernova remnant SNR 1987A seen in 1997 September and October with the Space Telescope Imaging Spectrograph. Part of this emission comes from a reverse shock located at ~75% of the radius of the inner boundary of the inner circumstellar ring and confined …
The spectral variability of the cool hypergiant rho Cassiopeiae
Lobel, A.; Parker, J. Wm.; de Jager, C. +3 more
We checked the change of the effective temperature with the atmospherical pulsation of rho Cas from combined analyses of optical spectra of 1993-95 and IUE spectra of 1979-81. We find an upper range for bigtriangleup T_eff =~ 750 K over a period of 16-17 months. We present a thorough study of the related absorption line profile changes from which …
HS0507+0434: a double DA degenerate with a ZZCeti component
Reimers, D.; Dreizler, S.; Heber, U. +6 more
HS0507+0434 and HS2240+1234 are two new common proper motion pairs of DA white dwarfs, discovered by the Hamburg Quasar Survey. Our model atmosphere analysis shows that HS0507+0434A has an effective temperature of 20000K and is remarkably young (tau_cool < 1Gyr) compared to the average cooling time of all known wide double degenerates (~ 3Gyr).…
Infrared lasers in the circumstellar disk of MWC 349
Quirrenbach, A.; Martin-Pintado, J.; Thum, C. +1 more
Observations of hydrogen recombination lines were made with the Infrared Space Observatory (ISO) towards the star MWC349, where the alpha -transitions at short millimeter and submillimeter wavelengths have been found to be masers. All alpha -line s in the ISO wavelength range from 2.4 to 190mu m (quantum numbers n=4 to 15) were detected. We find t…
A new determination of the local distribution of interstellar NaI
Crifo, F.; Lallement, R.; Welsh, B. Y.
We present galactic maps of the distribution of neutral sodium absorption column density using the newly determined Hipparcos satellite distances for a total of 290 stars lying within 250pc of the Sun. These maps now replace those originally presented in Welsh {et al./} (1994). The Local Bubble is now seen to be a neutral gas-free cavity (nH<…
NGC 2264 IRS: Evidence for Triggered Star Formation
Schneider, Glenn; Thompson, Rodger I.; Corbin, Michael R. +1 more
As part of its commissioning process the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) obtained images of the infrared source NGC 2264 IRS, also known as Allen's source, in three colors . In addition to the completely overexposed image of IRS there are six point objects, never previously observed, at projected separations of 2.6" to 4…