Search Publications
Relation between Thermal and Magnetic Properties of Active Regions as a Probe of Coronal Heating Mechanisms
Shibata, Kazunari; Yashiro, Seiji
We study the relation between thermal and magnetic properties of active regions in the corona observed with the soft X-ray telescope aboard Yohkoh. We derive the mean temperature and pressure of 64 mature active regions using the filter ratio technique, and examine the relationship of region size with temperature and pressure. We find that the tem…
Hubble Space Telescope Imaging in the Chandra Deep Field-South. I. Multiple Active Galactic Nucleus Populations
Marconi, A.; Gilli, R.; Tozzi, P. +9 more
We present preliminary results from imaging three Hubble Space Telescope (HST) Wide Field Planetary Camera 2 fields in V and I within the Chandra Deep Field-South (CDF-S). HST's sensitivity and resolution are sufficient to reveal optical counterparts for 24 of the 26 CDF-S X-ray sources detected in the 300 ks X-ray catalog and determine the morpho…
Hubble Space Telescope STIS Spectroscopy of VW Hydri during Early Quiescence following a Superoutburst
Szkody, Paula; Sion, Edward M.; Hubeny, Ivan +3 more
Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Lyα, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclea…
Millihertz Optical/Ultraviolet Oscillations in 4U 1626-67: Evidence for a Warped Accretion Disk
O'Donoghue, Darragh; Chakrabarty, Deepto; Homer, Lee +1 more
We have detected large-amplitude 0.3-1.2 mHz quasi-periodic oscillations (QPOs) from the low-mass X-ray binary pulsar 4U 1626-67/KZ TrA, using UV photometry from the Hubble Space Telescope and ground-based optical photometry. These 1 mHz QPOs, which have coherence (ν/Δν)~8, are entirely distinct from the 130 mHz pulsar spin frequency, a previously…
Far Ultraviolet Spectroscopic Explorer Observations of Interstellar Gas toward the Small Magellanic Cloud Star Sk 108
Savage, B. D.; Shull, J. M.; Sembach, K. R. +10 more
We discuss the interstellar absorption lines found in Far Ultraviolet Spectroscopic Explorer spectra of the Wolf-Rayet binary Sk 108, which is located in the northeastern part of the main ``bar'' of the Small Magellanic Cloud. The spectra cover the 988-1187 Å wavelength range at a resolution of about 12,000 and a signal-to-noise ratio of 20-40. We…
Discovery of the Galaxy Proximity Effect and Implications for Measurements of the Ionizing Background Radiation at Low Redshifts
Chen, Hsiao-Wen; Lanzetta, Kenneth M.; Webb, John K. +1 more
We present an analysis of galaxy and quasi-stellar object (QSO) absorption line pairs toward 24 QSOs at redshifts between z~0.2 and 1 in an effort to establish the relationship between galaxies and absorption lines in physical proximity to QSOs. We demonstrate the existence of a galaxy proximity effect, in that galaxies in the vicinities of QSOs d…
Near-Infrared Spectroscopy and Hubble Space Telescope Imaging of a Dusty Starburst Extremely Red Object
Kneib, J. -P.; Smith, Graham P.; Treu, Tommaso +3 more
We present near-infrared spectroscopy and Hubble Space Telescope (HST) imaging of ERO J164023+4644, an Extremely Red Object (ERO) with (R-K)=5.9 at z=1.05 that has been detected by Infrared Space Observatory (ISO) at 15 µm. ERO J164023 resembles a disk galaxy, with an optical/infrared spectral energy distribution that is strongly reddened by…
New Hubble Space Telescope Spectra of QSO PG 1718+4807: No Evidence for Strong Deuterium Absorption
O'Meara, John M.; Burles, Scott; Tytler, David +6 more
The zabs~0.701 absorption system toward QSO PG 1718+4807 is the only example of a QSO absorption system which might have a deuterium/hydrogen ratio approximately 10 times the value found toward other QSOs. We have obtained new Space Telescope Imaging Spectrograph spectra from the Hubble Space Telescope of the Lyα and Lyman limit regions…
Simultaneous Chandra and Hubble Space Telescope Observations of SMC X-1
McCray, R.; Raymond, J. C.; Kallman, T. +3 more
We present first results from simultaneous ultraviolet (Hubble Space Telescope/STIS) and X-ray (Chandra/ACIS) observations of the SMC X-1/SK 160 eclipsing binary system. Observations covering four orbital phases during each of the X-ray high and X-ray low states were taken in 2000 October-November and 2001 April. The ultraviolet P Cygni lines show…
Observations of Lyα Absorption in a Triple Quasar System
Impey, C. D.; Foltz, C. B.; Young, P. A.
We have obtained follow-up observations of the quasar pair LBQS 0107-025A and B and new observations of the nearby quasar LBQS 0107-0232 with the Hubble Space Telescope Faint Object Spectrograph. Extended wavelength coverage of LBQS 0107-025A and B using the G270H grating was also obtained. This triple system is unique in providing sensitivity to …