Search Publications
X-Raying the Ultraluminous Infrared Starburst Galaxy and Broad Absorption Line QSO Markarian 231 with Chandra
Brandt, W. N.; Garmire, G. P.; Chartas, G. +2 more
With 40 ks of Chandra ACIS-S3 exposure, new information on both the starburst and QSO components of the X-ray emission of Markarian 231, an ultraluminous infrared galaxy and broad absorption line QSO, has been obtained. The bulk of the X-ray luminosity is emitted from an unresolved nuclear point source, and the spectrum is remarkably hard, with th…
The Orientation of Jets Relative to Dust Disks in Radio Galaxies
Clarke, C. J.; Pringle, J. E.; Schmitt, H. R. +1 more
We use Hubble Space Telescope broadband images and VLA and VLBI continuum data to study the three-dimensional orientation of jets relative to nuclear dust disks in 20 radio galaxies. The comparison between the position angles of the jets and those of the dust disk major axes shows a wide distribution, suggesting that they are not aligned preferent…
A Chandra X-Ray Study of Cygnus A. II. The Nucleus
Terashima, Yuichi; Wilson, Andrew S.; Young, Andrew J. +2 more
We report Chandra Advanced CCD Imaging Spectrometer and quasi-simultaneous Rossi X-Ray Timing Explorer (RXTE) observations of the nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the properties of the active nucleus. In the Chandra observation, the hard (>a few keV) X-ray emission is spatially unresolved with a size &l…
Hubble Space Telescope/NICMOS Imaging Survey of the Ophiuchus (Lynds 1688) Cluster
Di Francesco, James; Myers, Philip C.; Allen, Lori E. +3 more
We present a catalog of near-infrared photometry of young stars associated with the Ophiuchus molecular cloud based on observations made with the Hubble Space Telescope NICMOS3 camera at 1.1 and 1.6 µm. Our survey covers 0.02 deg2 centered on the dense molecular cores in Lynds 1688. We detect 165 sources at 1.6 µm and 65 sou…
Chandra Discovery of Luminous Supersoft X-Ray Sources in M81
Wu, Kinwah; Tennant, Allyn F.; Swartz, Douglas A. +2 more
A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals nine luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the context of prevailing physical models for supersoft sources. It is shown that the sample falls within expectat…
The Spectral Components of SS 433
Wang, Z.; Gies, D. R.; McSwain, M. V. +3 more
We present results from new optical and UV spectroscopy of the unusual binary system SS 433, and we discuss the relationship of the particular spectral components that we observe to the properties of the binary. These spectral components include1. The continuum spectrum, which we associate with flux from the super-Eddington accretion disk and the …
Hubble Space Telescope Spectra of GW Librae: A Hot Pulsating White Dwarf in a Cataclysmic Variable
Szkody, Paula; Howell, Steve B.; Sion, Edward M. +1 more
We have obtained Hubble Space Telescope UV spectra of the white dwarf in GW Lib, the only known nonradially pulsating white dwarf in a cataclysmic variable and the first known DAZQ variable. The UV light curve reveals large-amplitude (10%) pulsations in the UV with the same periods (646, 376, and 237 s) as those seen at optical wavelengths, but th…
The Heavy-Element Enrichment of Lyα Clouds in the Virgo Supercluster
Gull, T. R.; Davé, R.; Heap, S. R. +11 more
Using high signal-to-noise ratio echelle spectra of 3C 273 obtained with the Space Telescope Imaging Spectrograph (resolution of 7 km s-1 FWHM), we constrain the metallicities of two Lyα clouds in the vicinity of the Virgo Cluster. We detect C II, Si II, and Si III absorption lines in the Lyα absorber at zabs=0.00530. Previou…
A Study of π Aquarii during a Quasi-normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity
Bjorkman, Karen S.; Miroshnichenko, Anatoly S.; McDavid, David +1 more
We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star π Aqr. Observational data collected from the literature were used to study the star's variations over the last four decades. The star is identified with the IR sources F22227+0107 in the IRAS Faint Point Source Catalog and M…
PKS 1830-211: A Face-on Spiral Galaxy Lens
Rix, Hans-Walter; Winn, Joshua N.; Kochanek, Christopher S. +3 more
We present new Hubble Space Telescope images of the gravitational lens PKS 1830-211, which allow us to characterize the lens galaxy and update the determination of the Hubble constant (H0) from this system. The I-band image shows that the lens galaxy is a face-on spiral galaxy with clearly delineated spiral arms. The southwestern image …