Search Publications
Multiple Outbursts of a Cataclysmic Variable in the Globular Cluster M22
Sumi, T.; MOA Collaboration; Bond, I. A. +19 more
We present a 4 yr light curve of a cataclysmic variable in M22, based on an analysis of accumulated data from the Microlensing Observations in Astrophysics (MOA) microlensing survey. The position of the star coincides with that of a transient event observed by the Hubble Space Telescope (HST) in 1999, originally attributed to microlensing but late…
Photometric Redshift of the GRB 981226 Host Galaxy
Christensen, L.; Gorosabel, J.; Hjorth, J.
No optical afterglow was found for the dark burst GRB 981226, and hence no absorption redshift has been obtained. We here use ground-based and space imaging observations to analyze the spectral energy distribution (SED) of the host galaxy. By comparison with synthetic template spectra, we determine the photometric redshift of the GRB 981226 host t…
Discovery of an X-Ray Nova in M31
Williams, Benjamin F.; Kong, Albert K. H.; Murray, Stephen S. +2 more
We have obtained snapshot images of an X-ray nova in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys. The Chandra position of the X-ray nova was R.A.=00h44m06.68s 68+/-1.74s, decl.=+41deg12'20.0"+/-2.31" (J2000.0). A follow-up HST observation 24 days later reveale…
Identification of the Source Region of a ``Halo'' Coronal Mass Ejection Using Meter-Wavelength Radio Data
Ramesh, R.; Kathiravan, C.
We present meter-wavelength observations of the solar corona close to the onset of the ``halo'' coronal mass ejection (CME) of 1998 January 21 and estimate the change in electron density with time through a reproduction of the observed two-dimensional radio brightness distribution using a ray-tracing technique. Our calculations show that the avera…
High-Resolution Spectroscopy of X-Ray Quasars: Searching for the X-Ray Absorption from the Warm-Hot Intergalactic Medium
Canizares, Claude R.; Marshall, Herman L.; Fang, Taotao
We present a survey of six low- to moderate-redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the warm-hot intergalactic medium. All the X-ray spectra can be fitted by a power law with the neutral hydrogen absorption method. The residuals that may …
Near-Infrared Properties of Faint X-Ray Sources from NICMOS Imaging in the Chandra Deep Fields
Teplitz, Harry I.; McCarthy, Patrick J.; Malkan, Matthew A. +2 more
We measure the near-infrared properties of 42 X-ray-detected sources from the Chandra Deep Fields North and South, the majority of which lie within the NICMOS Hubble Deep Field-North and Ultra Deep Field. We detect all 42 Chandra sources with NICMOS, with 95% brighter than H160=24.5. We find that X-ray sources are most often in the brig…
Hubble Space Telescope Imaging of the Ultracompact Blue Dwarf Galaxy HS 0822+3542: An Assembling Galaxy in a Local Void?
Somerville, Rachel S.; Windhorst, Rogier A.; Vacca, William D. +2 more
We present deep U-band, narrow V-band, and I-band images and photometry of the ultracompact blue dwarf galaxy HS 0822+3542 obtained with the Advanced Camera for Surveys/High Resolution Channel of the Hubble Space Telescope. This object is also extremely metal-poor [12+log(O/H)=7.45] and resides in a nearby void. The images resolve it into two phys…
Chandra and HST Study of a New Transient X-Ray Source in M31
Williams, Benjamin F.; McClintock, Jeffrey E.; Murray, Stephen S. +2 more
We present X-ray and optical observations of a new transient X-ray source in M31 first detected 2004 May 23 at R.A.=00h43m09.940s+/-0.65", decl.=41deg23'32.49"+/-0.66". The X-ray light curve shows two peaks separated by several months, reminiscent of many Galactic X-ray novae. The location and X-ray spec…
The GRB 011211 X-Ray Lines: Toward Resolving the Significance Debate
Ricker, G.; Vanderspek, R.; Ford, P. +4 more
We demonstrate for the GRB 011211 X-ray afterglow lines that the significance estimation methods used by Reeves et al. and Rutledge & Sako are consistent and that the conflicting estimates found by those authors arise from different assumptions in the continuum modeling. If the column density is fixed at the Galactic value as in the Reeves et …
Galaxy Evolution Explorer Observations of the Ultraviolet Surface Brightness and Color Profiles of the Local Group Elliptical Galaxy M32 (NGC 221)
Heckman, Timothy M.; Madore, Barry F.; Rich, R. Michael +22 more
M32, the compact elliptical galaxy companion to the Andromeda spiral galaxy, has been imaged by the Galaxy Evolution Explorer (GALEX) in two UV bands, centered at ~1500 (far-ultraviolet [FUV]) and 2300 Å (near-ultraviolet). The imaging data have been carefully decomposed so as to properly account for the complicated background contamination from t…