Search Publications
Evidence for a Sudden Magnetic Field Reconfiguration in Soft Gamma Repeater 1900+14
Hurley, Kevin; Kouveliotou, Chryssa; Göǧüş, Ersin +5 more
We report the detection of large flux changes in the persistent X-ray flux of soft gamma repeater (SGR) 1900+14 during its burst active episode in 1998. Most notably, we find a factor of ~700 increase in the nonburst X-ray flux following the August 27 flare, which decayed in time as a power law. Our measurements indicate that the pulse fraction re…
HST STIS Observations of PG 0946+301: The Highest Quality UV Spectrum of a BALQSO
Pettini, Max; Brandt, W. N.; Laor, Ari +16 more
We describe deep (40 orbits) Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the broad absorption line (BAL) quasi-stellar object (QSO) PG 0946+301 and make them available to the community. These observations are the major part of a multiwavelength campaign on this object aimed at determining the ionization equili…
The Giant Flare of 1998 August 27 from SGR 1900+14. I. An Interpretive Study of BeppoSAX and Ulysses Observations
Hurley, K.; Feroci, M.; Duncan, R. C. +1 more
The giant flare of 1998 August 27 from SGR 1900+14 was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft gamma repeater (SGR) in our Galaxy by more than an order of magnitude; and it showed a remarkable four-peake…
On the Origin of Infrared Plateau Features in Proto-Planetary Nebulae
Volk, Kevin; Kwok, Sun; Bernath, Peter
The emission profiles of the 8 and 12 µm plateau features are derived from the Infrared Space Observatory spectra of proto-planetary nebulae. We suggest that these plateau features are primarily the result of alkane and alkene side groups on very large aromatic molecules and small carbonaceous particles. The relationship between the narrow a…
Ultraviolet Line Spectra of Metal-poor Star-forming Galaxies
Pettini, Max; Robert, Carmelle; Heckman, Timothy M. +3 more
We present synthetic ultraviolet spectra of metal-poor star-forming galaxies that were calculated with the Starburst99 package. A new spectral library was generated from Hubble Space Telescope observations of O stars in the Large and Small Magellanic Clouds. The corresponding mean metallicity of the synthetic spectra is approximately 1/4 Zsol…
Observational Estimates for the Mass-Loss Rates of α Centauri and Proxima Centauri Using Hubble Space Telescope Lyα Spectra
Zank, Gary P.; Wood, Brian E.; Linsky, Jeffrey L. +1 more
We study H I Lyα absorption observed by the Hubble Space Telescope toward the nearby binary system α Centauri (G2 V + K0 V) and its distant companion star Proxima Centauri (M5.5 Ve). Absorption from heliospheric H I heated by the solar wind/interstellar medium interaction is observed toward both α Cen and Proxima Cen. Absorption from analogous ``a…
Methylpolyynes and Small Hydrocarbons in CRL 618
Waters, L. B. F. M.; Cernicharo, José; Tielens, A. G. G. M. +5 more
We report on the detection with the Infrared Space Observatory of strong infrared absorption from NH3 and C2H4 in CRL 618. The observed NH3 and C2H4 bands arise from a region with kinetic temperatures ~=200 K, i.e., the dense gas in the photodissociation region associated to the den…
Luminous Compact Galaxies at Intermediate Redshifts: Progenitors of Bulges of Massive Spirals?
Infante, Leopoldo; Hammer, François; Thuan, Trinh X. +2 more
VLT spectra of 14 luminous compact galaxies (LCGs) reveal strong metallic absorption-line systems as well as narrow and intense emission lines. Their gas extinction is found to be large (AV~1.5 mag), leading to an upward revision of their star formation rate (SFR) to an average value of ~40 Msolar yr-1. Large extin…
High-Resolution Near-Infrared Images and Models of the Circumstellar Disk in HH 30
Schneider, Glenn; Rieke, Marcia; Wood, Kenneth +6 more
We present Hubble Space Telescope near-infrared camera and multiobject spectrometer observations of the reflection nebulosity associated with the T Tauri star HH 30. The images show the scattered-light pattern characteristic of a highly inclined, optically thick disk with a prominent dust lane whose width decreases with increasing wavelength. The …
Hubble Space Telescope Spectroscopy of V471 Tauri: Oversized K Star, Paradoxical White Dwarf
Bond, Howard E.; Sion, Edward M.; O'Brien, M. Sean
We have used the Goddard High Resolution Spectrograph on board the Hubble Space Telescope to obtain Lyα spectra of the hot white dwarf (WD) component of the short-period eclipsing DA+dK2 precataclysmic binary V471 Tauri, a member of the Hyades star cluster. Radial velocities of the WD were determined from eight post-COSTAR spectra obtained near th…