Search Publications
Quasi-periodic Oscillations and Strongly Comptonized X-Ray Emission from Holmberg IX X-1
Rao, A. R.; Dewangan, G. C.; Griffiths, R. E.
We report the discovery of a 200 mHz quasi-periodic oscillation (QPO) in the X-ray emission from a bright ultraluminous X-ray source (ULX), Holmberg IX X-1, using a long XMM-Newton observation. The QPO has a centroid at νQPO=202.5+4.9-3.8 mHz, a coherence Q≡νQPO/ΔνFWHM~9.3, and an amplitude (r…
An Ultraviolet to Mid-Infrared Study of the Physical and Wind Properties of HD 164270 (WC9) and Comparison to BD +30 3639 ([WC9])
Smith, J. D.; Morris, P. W.; Crowther, Paul A.
We present new Spitzer IRS observations of HD 164270 (WC9, WR103). A quantitative analysis of the UV, optical, near-, and mid-IR spectra of HD 164270 is presented, allowing for line blanketing and wind clumping, revealing T*~48 kK, logL/Lsolar~4.9, and M˙~10-5 Msolar yr-1 for a volume filling …
Far-Ultraviolet and X-Ray Observations of VV 114: Feedback in a Local Analog to Lyman Break Galaxies
Ptak, A.; Meurer, G.; Aloisi, A. +4 more
We have analyzed Far Ultraviolet Spectroscopic Explorer (FUSE), XMM-Newton, and Chandra observations of VV 114, a local galaxy merger with strong similarities to typical high-redshift Lyman break galaxies (LBGs). Diffuse thermal X-ray emission encompassing VV 114 has been observed by Chandra and XMM-Newton. This region of hot (kT~0.59 keV) gas has…
Tracking Large-Scale Propagating Coronal Wave Fronts (EIT Waves) using Automated Methods
Wills-Davey, M. J.
Recently developed mapping algorithms allow automated tracking of a propagating coronal wave, enabling the finding of reproducible fronts and propagation trajectories. Coronal observations taken by the Transition Region and Coronal Explorer (TRACE) on 1998 June 13 show a large-scale bright wave front, comparable to ``EIT waves'' seen with the Extr…
A Spitzer Study of Comets 2P/Encke, 67P/Churyumov-Gerasimenko, and C/2001 HT50 (LINEAR-NEAT)
Gehrz, Robert D.; Woodward, Charles E.; Pittichová, Jana +8 more
We present infrared images and spectra of comets 2P/Encke, 67P/Churyumov-Gerasimenko, and C/2001 HT50 (LINEAR-NEAT) as part of a larger program to observe comets inside of 5 AU from the Sun with the Spitzer Space Telescope. The nucleus of comet 2P/Encke was observed at two vastly different phase angles (20° and 63°). Model fits to the spectral ene…
MAGIC Observations of Very High Energy γ-Rays from HESS J1813-178
Bastieri, D.; Ciprini, S.; Longo, F. +130 more
Recently, the HESS collaboration has reported the detection of γ-ray emission above a few hundred GeV from eight new sources located close to the Galactic plane. The source HESS J1813-178 has sparked particular interest, as subsequent radio observations imply an association with supernova remnant G12.82-0.02. Triggered by the detection in very hig…
White Dwarf-Red Dwarf Systems Resolved with the Hubble Space Telescope. I. First Results
Hoard, D. W.; Farihi, J.; Wachter, S.
First results are presented for a Hubble Space Telescope (HST) Advanced Camera for Surveys snapshot study of white dwarfs with likely red dwarf companions. Of 48 targets observed and analyzed so far, 27 are totally or partially resolved into two or more components, while an additional 15 systems are almost certainly unresolved binaries. These resu…
Surface Magnetism Effects in Time-Distance Helioseismology
Zhao, Junwei; Kosovichev, Alexander G.
Recent observations of helioseismic holography revealed that magnetic fields that are inclined relative to the line-of-sight direction could cause systematic variations in measured acoustic phase shifts (hereafter, inclined magnetic field effect) and that the presence of surface magnetic field may shift the phases and impair the coherence of acous…
Near-Infrared Synthetic Images of Protostellar Disks and Envelopes
Stassun, K.; Wood, K.; Whitney, B. A. +1 more
We present a grid of near-infrared (IR) synthetic images of pre-main-sequence stars at different stages of evolution, which we simulate by varying envelope mass, disk radius and mass, and outflow cavity shape. Our aim is to determine how variations in physical properties of young stellar objects (e.g., mass infall rate, disk size) affect their obs…
Large-Scale Activities Associated with the 2003 October 29 X10 Flare
Liu, Chang; Wang, Haimin; Deng, Na +2 more
We present a multiwavelength study focusing on the large-scale activities associated with the 2003 October 29 X10 flare and a halo CME. This event was strong enough to clearly show several large-scale activities, such as remote brightenings, Moreton waves at Hα off-bands, and type II radio bursts, which offers an excellent opportunity to clarify t…