Search Publications
Scattered X-rays in Obscured Active Galactic Nuclei and Their Implications for Geometrical Structure and Evolution
Koss, Michael; Ueda, Yoshihiro; Awaki, Hisamitsu +4 more
We construct a new sample of 32 obscured active galactic nuclei (AGNs) selected from the Second XMM-Newton Serendipitous Source Catalogue to investigate their multiwavelength properties in relation to the "scattering fraction," the ratio of the soft X-ray flux to the absorption-corrected direct emission. The sample covers a broad range of the scat…
A Galactic Origin for HE 0437-5439, The Hypervelocity Star Near the Large Magellanic Cloud
Anderson, Jay; Livio, Mario; Bond, Howard E. +4 more
We use Hubble Space Telescope imaging to measure the absolute proper motion of the hypervelocity star (HVS) HE 0437-5439, a short-lived B star located in the direction of the Large Magellanic Cloud (LMC). We observe (µα, µδ) = (+0.53 ± 0.25(stat) ± 0.33(sys), + 0.09 ± 0.21(stat) ± 0.48(sys)) mas yr-1. T…
Doppler-shift, Intensity, and Density Oscillations Observed with the Extreme Ultraviolet Imaging Spectrometer on Hinode
Muglach, K.; Mariska, John T.
Low-amplitude Doppler-shift oscillations have been observed in coronal emission lines in a number of active regions with the EUV Imaging Spectrometer (EIS) on the Hinode satellite. Both standing and propagating waves have been detected and many periods have been observed, but a clear picture of all the wave modes that might be associated with acti…
Submillimeter Array Identification of the Millimeter-selected Galaxy SSA22-AzTEC1: A Protoquasar in a Protocluster?
Yun, M. S.; Lehmer, B. D.; Alexander, D. M. +19 more
We present results from Submillimeter Array (SMA) 860 µm subarcsecond astrometry and multiwavelength observations of the brightest millimeter (S 1.1mm = 8.4 mJy) source, SSA22-AzTEC1, found near the core of the SSA22 protocluster that is traced by Lyα-emitting galaxies at z = 3.09. We identify a 860 µm counterpart with a flu…
The AGN, Star-forming, and Morphological Properties of Luminous IR-bright/optically-faint Galaxies
Alexander, D. M.; Egami, E.; Rieke, G. H. +2 more
We present the active galactic nucleus (AGN), star-forming, and morphological properties of a sample of 13 MIR-luminous (f 24 >~ 700 µJy) IR-bright/optically-faint galaxies (IRBGs, f 24/f R >~ 1000). While these z ~ 2 sources were drawn from deep Chandra fields with >200 ks X-ray coverage, only seven…
A Sea Change in Eta Carinae
Walborn, Nolan R.; Humphreys, Roberta M.; Davidson, Kris +4 more
Major stellar-wind emission features in the spectrum of η Car have recently decreased by factors of order 2 relative to the continuum. This is unprecedented in the modern observational record. The simplest, but unproven, explanation is a rapid decrease in the wind density.
AKARI Observations of Brown Dwarfs. I. CO and CO2 Bands in the Near-infrared Spectra
Yamamura, Issei; Tanabé, Toshihiko; Tsuji, Takashi
Near-infrared medium-resolution spectra of seven bright brown dwarfs are presented. The spectra were obtained with the Infrared Camera on board the infrared astronomical satellite AKARI, covering 2.5-5.0 µm with a spectral resolution of approximately 120. The spectral types of the objects range from L5 to T8 and enable us to study the spectr…
Taming the Invisible Monster: System Parameter Constraints for epsilon Aurigae from the Far-ultraviolet to the Mid-infrared
Stencel, R. E.; Hoard, D. W.; Howell, S. B.
We have assembled new Spitzer Space Telescope IRAC observations of the mysterious binary star epsilon Aurigae, along with archival far-ultraviolet to mid-infrared data, to form an unprecedented spectral energy distribution (SED) spanning 3 orders of magnitude in wavelength from 0.1 µm to 100 µm. The observed SED can be reproduced using…
X-ray and Radio Variability of M31*, The Andromeda Galaxy Nuclear Supermassive Black Hole
Melia, Fulvio; Murray, Stephen S.; Garcia, Michael R. +6 more
We confirm our earlier tentative detection of M31* in X-rays and measure its light curve and spectrum. Observations in 2004-2005 find M31* rather quiescent in the X-ray and radio. However, X-ray observations in 2006-2007 show M31* to be highly variable at times. A separate variable X-ray source is found near P1, the brighter of the two optical nuc…
The Structure of the Accretion Disk in the Accretion Disk Corona X-ray Binary 4U 1822-371 at Optical and Ultraviolet Wavelengths
Cornell, Mark E.; Robinson, Edward L.; Hynes, Robert I. +2 more
The eclipsing low-mass X-ray binary 4U 1822-371 is the prototypical accretion disk corona (ADC) system. We have obtained new time-resolved UV spectroscopy of 4U 1822-371 with the Advanced Camera for Surveys/Solar Blind Channel on the Hubble Space Telescope and new V- and J-band photometry with the 1.3 m SMARTS telescope at Cerro Tololo Inter-Ameri…