Search Publications
High-resolution X-Ray Spectroscopy Reveals the Special Nature of Wolf-Rayet Star Winds
Hamann, W. -R.; Oskinova, L. M.; Ignace, R. +3 more
We present the first high-resolution X-ray spectrum of a putatively single Wolf-Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and t…
The Nature of the Bright ULX X-2 in NGC 3921: A Chandra Position and HST Candidate Counterpart
Fabian, A. C.; Miniutti, G.; Miller-Jones, J. C. A. +6 more
We report on Chandra observations of the bright ultraluminous X-ray (ULX) source in NGC 3921. Previous XMM-Newton observations reported in the literature show the presence of a bright ULX at a 0.5-10 keV luminosity of 2 × 1040 erg s-1. Our Chandra observation finds the source at a lower luminosity of ≈8 × 1039 erg …
Determination of the Heliospheric Radial Magnetic Field from the Standoff Distance of a CME-driven Shock Observed by the STEREO Spacecraft
Gopalswamy, Nat; Yashiro, Seiji; Kwon, Ryun-Young +2 more
We report on the determination of radial magnetic field strength in the heliocentric distance range from 6 to 120 solar radii (R ⊙) using data from Coronagraph 2 (COR2) and Heliospheric Imager I (HI1) instruments on board the Solar Terrestrial Relations Observatory spacecraft following the standoff-distance method of Gopalswamy & Ya…
Discovery of a Kiloparsec-scale X-Ray/Radio Jet in the z = 4.72 Quasar GB 1428+4217
Cheung, C. C.; Stawarz, Ł.; Siemiginowska, A. +4 more
We report the discovery of a one-sided 3farcs6 (24 kpc, projected) long jet in the high-redshift, z = 4.72, quasar GB 1428+4217 in new Chandra X-ray and Very Large Array (VLA) radio observations. This is the highest redshift kiloparsec-scale X-ray/radio jet known. Analysis of archival very long baseline interferometry 2.3 and 8.6 GHz data reveal a…
A Search for an Intermediate-mass Black Hole in the Core of the Globular Cluster NGC 6266
Harrison, Thomas E.; Baumgardt, Holger; McNamara, Bernard J. +1 more
It has long been thought that intermediate-mass black holes (IMBHs) might be located in the cores of globular clusters. However, studies attempting to confirm this possibility have been inconclusive. To refine the search for these objects, Baumgardt et al. completed a series of N-body simulations to determine the observational properties that a ho…
Elemental Abundances in the Possible Type Ia Supernova Remnant G344.7-0.1
Yamaguchi, H.; Tanaka, M.; Maeda, K. +5 more
Recent studies on the Galactic supernova remnant (SNR) G344.7-0.1 have commonly claimed its origin to be a core-collapse supernova (SN) explosion, based on its highly asymmetric morphology and/or proximity to a star-forming region. In this paper, however, we present an X-ray spectroscopic study of this SNR using Suzaku, which is supportive of a Ty…
Deep Chandra Monitoring Observations of NGC 4649. II. Wide-field Hubble Space Telescope Imaging of the Globular Clusters
Brodie, Jean P.; Zezas, Andreas; Strader, Jay +7 more
We present g and z photometry and size estimates for globular clusters (GCs) in the massive Virgo elliptical NGC 4649 (M60) using a five-pointing Hubble Space Telescope/Advanced Camera for Surveys mosaic. The metal-poor GCs show a monotonic negative metallicity gradient of -0.43 ± 0.10 dex per dex in radius over the full radial range of the data, …
Deep Hubble Space Telescope Imaging in NGC 6397: Stellar Dynamics
Anderson, J.; Rich, R. M.; Dotter, A. +9 more
Multi-epoch observations with the Advanced Camera for Surveys on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within NGC 6397. We are able to confront analytic models of the globular cluster with the observed stellar proper motions. The measured proper motions probe well along the main sequence from 0.8 t…
Hubble Space Telescope Narrowband Search for Extended Lyα Emission around Two z > 6 Quasars
Hennawi, Joseph F.; Strauss, Michael A.; Rix, Hans-Walter +8 more
We search for extended Lyα emission around two z > 6 quasars, SDSS J1030+0524 (z = 6.309) and SDSS J1148+5251 (z = 6.419) using Wide Field Camera 3 narrowband filters on board the Hubble Space Telescope. For each quasar, we collected two deep, narrowband images, one sampling the Lyα line+continuum at the quasar redshifts and one of the continuu…
Spatially Dependent Heating and Ionization in an ICME Observed by Both ACE and Ulysses
Laming, J. Martin; von Steiger, Rudolf; Rakowski, Cara E. +1 more
The 2005 January 21 interplanetary coronal mass ejection (ICME) observed by multiple spacecraft at L1 was also observed from January 21-February 4 at Ulysses (5.3 AU). Previous studies of this ICME have found evidence suggesting that the flanks of a magnetic cloud like structure associated with this ICME were observed at L1 while a more central cu…