Search Publications
Outflows from Massive Young Stellar Objects as Seen with the Infrared Array Camera
Smith, Howard A.; Marengo, M.; Hora, J. L. +1 more
The bipolar outflow from the massive star-forming cluster in DR 21 is one of the most powerful known, and in IRAC images the outflow stands out by virtue of its brightness at 4.5 µm (band 2). Indeed, IRAC images of many Galactic and extragalactic star formation regions feature prominent band 2 morphologies. We have analyzed archival ISO SWS …
An Overdensity of Galaxies near the Most Distant Radio-loud Quasar
Ford, H. C.; Demarco, R.; Infante, L. +41 more
A 5 arcmin2 region around the luminous radio-loud quasar SDSS J0836+0054 (z=5.8) hosts a wealth of associated galaxies, characterized by very red (1.3<i775-z850<2.0) color. The surface density of these z~5.8 candidates is approximately 6 times higher than the number expected from deep ACS fields. This is one …
Magnetic Causes of Solar Coronal Mass Ejections: Dominance of the Free Magnetic Energy over the Magnetic Twist Alone
Falconer, D. A.; Moore, R. L.; Gary, G. A.
We examine the magnetic causes of coronal mass ejections (CMEs) by examining, along with the correlations of active-region magnetic measures with each other, the correlations of these measures with active-region CME productivity observed in time windows of a few days, either centered on or extending forward from the day of the magnetic measurement…
A Galactic Origin for the Local Ionized X-Ray Absorbers
Canizares, Claude R.; Wolfire, Mark; Fang, Taotao +1 more
Recent Chandra and XMM-Newton observations of distant quasars have shown strong local (z~0) X-ray absorption lines from highly ionized gas, primarily He-like oxygen. The nature of these X-ray absorbers, i.e., whether they are part of the hot gas associated with the Milky Way or part of the intragroup medium in the Local Group, remains a puzzle due…
XMM-Newton Observations of Four Millisecond Pulsars
Zavlin, Vyacheslav E.
I present an analysis of the XMM-Newton observations of four millisecond pulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The new data provide strong evidence of thermal emission in the X-ray flux detected from the first three objects. This thermal component is best interpreted as radiation from pulsar polar caps covered with a nonmagn…
XTE J1739-302 as a Supergiant Fast X-Ray Transient
Negueruela, I.; Swank, J. H.; Markwardt, C. B. +4 more
XTE J1739-302 is a transient X-ray source with unusually short outbursts, lasting on the order of hours. Here we give a summary of X-ray observations we have made of this object in outburst with the Rossi X-Ray Timing Explorer (RXTE) and at a low level of activity with the Chandra X-Ray Observatory, as well as observations made by other groups. Vi…
Discovery of a Population of Pre-Main-Sequence Stars in NGC 346 from Deep Hubble Space Telescope ACS Images
Tosi, M.; Sabbi, E.; Nota, A. +9 more
We report the discovery of a rich population of low-mass stars in the young, massive NGC 346 star-forming region in the Small Magellanic Cloud from deep V, I, and Hα images taken with the Hubble Space Telescope Advanced Camera for Surveys. These stars have likely formed together with the NGC 346 cluster, ~=3-5 Myr ago. Their magnitudes and colors …
Evolution of the Color-Magnitude Relation in High-Redshift Clusters: Blue Early-Type Galaxies and Red Pairs in RDCS J0910+5422
Demarco, R.; Infante, L.; Zheng, W. +43 more
The color-magnitude relation has been determined for the RDCS J0910+5422 cluster of galaxies at redshift z=1.106. Cluster members were selected from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) images, combined with ground-based near-IR imaging and optical spectroscopy. The observed early-type color-magnitude relation (CMR) in …
A Persistent High-Energy Flux from the Heart of the Milky Way: INTEGRAL's View of the Galactic Center
Terrier, R.; Lund, N.; Bélanger, G. +6 more
Highly sensitive imaging observations of the Galactic center (GC) at high energies with an angular resolution of order 10' is a very recent development in the field of high-energy astrophysics. The IBIS/ISGRI imager on the INTEGRAL observatory detected for the first time a hard X-ray source, IGR J17456-2901, located within 1' of Sagittarius A* (Sg…
Molecular Gas Dynamics in NGC 6946: A Bar-driven Nuclear Starburst ``Caught in the Act''
Böker, Torsten; Schinnerer, Eva; Emsellem, Eric +1 more
We present high angular resolution (~1" and 0.6") millimeter interferometric observations of the 12CO(1-0) and 12CO(2-1) line emission in the central 300 pc of the late-type spiral galaxy NGC 6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), allow the first detection of a molecular gas spiral in th…