Search Publications
Seismic Imaging of the Far Hemisphere of the Sun
Braun, D. C.; Lindsey, C.
We apply phase-sensitive helioseismic holography to Solar and Heliospheric Observatory/Michelson Dopper Imager data to demonstrate how acoustic travel-time perturbations may be mapped over the entire portion of the Sun facing away from the Earth, including the polar regions. In addition to offering significant improvements to ongoing space weather…
Multicolor Observations of the GRB 000926 Afterglow
Axelrod, T. S.; Price, P. A.; Harrison, F. A. +25 more
We present multicolor light curves of the optical afterglow of gamma-ray burst (GRB) 000926. Beginning ~1.5 days after the burst, the light curves of this GRB steepen measurably. The existence of such achromatic breaks is usually taken to be an important observational signature that the ejecta are not expanding isotropically but rather have a coll…
FUSE and Hubble Space Telescope/STIS Observations of Hot and Cold Gas in the AB Aurigae System
Deleuil, M.; Bouret, J. -C.; Roberge, A. +9 more
We present the first observations of a Herbig Ae star with a circumstellar disk by the Far-Ultraviolet Spectroscopic Explorer (FUSE) as well as a simultaneous observation of the star obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show emission and absorption features arising from gas…
Detection of an X-Ray Pulsar Wind Nebula and Tail in SNR N157B
Gotthelf, E. V.; Wang, Q. D.; Chu, Y. -H. +1 more
We report Chandra X-ray observations of the supernova remnant N157B in the Large Magellanic Cloud, which are presented together with an archival Hubble Space Telescope optical image and a radio continuum map for comparison. This remnant contains the recently discovered 16 ms X-ray pulsar PSR J0537-6910, the most rapidly rotating young pulsar known…
An Imaging and Spectroscopic Study of the zabs=3.38639 Damped Lyα System in Q0201+1120: Clues to Star Formation at High Redshift
Pettini, Max; Ellison, Sara L.; Shapley, Alice E. +1 more
We present the results of a series of imaging and spectroscopic observations aimed at identifying and studying the galaxy responsible for the zabs=3.38639 damped Lyα system in the zem=3.61 quasar Q0201+1120. We find that the damped Lyα systems (DLA) is part of a concentration of matter that includes at least four galaxies (pr…
Mass-losing Semiregular Variable Stars in Baade's Windows
Genzel, R.; Alard, C.; Blommaert, J. A. D. L. +38 more
By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 µm) and MACHO V and R light curves are assembled for approximately 300 stars in the Baade's windows of low extinction toward the Galac…
Oxygen Abundances in Metal-poor Stars (-2.2<[Fe/H]<-1.2) from Infrared OH Lines
Meléndez, Jorge; Barbuy, Beatriz; Spite, François
Infrared OH lines at 1.55-1.56 µm in the H band were obtained with the Phoenix high-resolution spectrograph at the 2.1 m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample stars have been carried out, deriving stellar parameters based on two methods: (a) spectroscopic paramete…
Intrinsic and Reprocessed Optical Emission from the Companion to PSR J2051-0827
Kulkarni, S. R.; van Kerkwijk, M. H.; Stappers, B. W. +1 more
Hubble Space Telescope observations of the companion to the eclipsing millisecond pulsar PSR J2051-0827 have revealed its ``dark'' side. The R magnitude at minimum is ~26, while the difference between the side heated by the impinging pulsar radiation and the unirradiated side is ~3.3 mag. For the first time, these data show that there is an asymme…
Cepheid Calibration of the Peak Brightness of Type IA Supernovae. X. SN 1991T in NGC 4527
Panagia, N.; Saha, A.; Labhardt, Lukas +5 more
Repeated imaging observations have been made of NGC 4527 with the Hubble Space Telescope between 1999 April and June, over an interval of 69 days. Images were obtained on 12 epochs in the F555W band and on five epochs in the F814W band. The galaxy hosted the Type Ia supernova SN 1991T, which showed relatively unusual behavior by having both an abn…
Detection of High-Latitude Waves of Solar Coronal Activity in Extreme-Ultraviolet Data from the Solar and Heliospheric Observatory EUV Imaging Telescope
Kosovichev, A. G.; Benevolenskaya, E. E.; Scherrer, P. H.
We present the results of an investigation of EUV coronal structures in 1996-2000 using the Solar and Heliospheric Observatory EIT data in 171, 195, 284, and 304 Å lines. During this period, poleward- and equatorward-migrating waves of solar activity have been found in axisymmetrical distributions of EUV intensity in all four lines. In the axisymm…