Search Publications
Discovery of Red-skewed K α Iron Line in Cyg X-2 with Suzaku
Laurent, Philippe; Titarchuk, Lev; Shaposhnikov, Nikolai
We report on the Suzaku observation of neutron star (NS) low-mass X-ray binary Cygnus X-2 which reveals a presence of the iron K α emission line. The line profile shows a significant red wing. This discovery increases the number of NS sources where red-skewed iron lines were observed and strongly suggests that this phenomenon is common …
Variable Stars in the Fornax dSph Galaxy. III. The Globular Cluster Fornax 5
Rest, Armin; Held, Enrico V.; Pritzl, Barton J. +8 more
We present a new study of the variable star population in globular cluster 5 of the Fornax dSph, based on B and V time series photometry obtained with the MagIC camera of the 6.5 m Magellan Clay telescope and complementary Hubble Space Telescope archive data. Light curves and accurate periodicities were obtained for 30 RR Lyrae stars and one SX Ph…
Hipparcos Calibration of the Tip of the Red Giant Branch
Bedding, Timothy R.; Tabur, Vello; Kiss, László L.
We have detected the tip of the red giant branch (TRGB) in the solar neighborhood using near-infrared photometry from the Two Micron All Sky Survey and DIRBE catalogs, and revised Hipparcos parallaxes. We confirm that the revised Hipparcos parallaxes are superior to the original ones, and that this improvement is necessary to detect the TRGB. We f…
Xmm-Newton X-Ray Detection of the High-Magnetic-Field Radio Pulsar PSR B1916+14
Zhu, Weiwei; Kaspi, Victoria M.; Gonzalez, Marjorie E. +1 more
Using observations made with the XMM-Newton Observatory, we report the first X-ray detection of the high-magnetic-field radio pulsar PSR B1916+14. We show that the X-ray spectrum of the pulsar can be well fitted with an absorbed blackbody with temperature in the range of 0.08-0.23 keV, or a neutron-star hydrogen atmosphere model with best-fit effe…
Structural Parameters of the Messier 87 Globular Clusters
Blakeslee, John P.; Harris, William E.; Madrid, Juan P. +1 more
We derive structural parameters for ~2000 globular clusters in the giant Virgo elliptical Messier 87 (M87) using extremely deep Hubble Space Telescope images in F606W (V) and F814W (I) taken with the ACS/WFC. The cluster scale sizes (half-light radii rh ) and ellipticities are determined from point-spread-function -convolved King-model …
On the Stellar Content of the Starburst Galaxy IC10
Walker, A. R.; Prada Moroni, P. G.; Degl'Innocenti, S. +17 more
We investigate the stellar content of the starburst dwarf galaxy IC10 using accurate and deep optical data collected with the Advanced Camera for Surveys and with the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope. The comparison between theory and observations indicates a clear change in age distribution when moving from the cen…
Physical Properties of Cooling Plasma in Quiescent Active Region Loops
Curdt, W.; Landi, E.; Hara, H. +1 more
In the present work, we use SOHO/SUMER, SOHO/UVCS, SOHO/EIT, SOHO/LASCO, STEREO/EUVI, and Hinode/EIS coordinated observations of an active region (AR 10989) at the west limb taken on 2008 April 8 to study the cooling of coronal loops. The cooling plasma is identified using the intensities of SUMER spectral lines emitted at temperatures in the 4.15…
Statistics of Flares Sweeping Across Sunspots
Zhang, Jun; Li, Leping
Flare ribbons are always dynamic and sometimes sweep across sunspots. After examining 588 (513 M-class and 75 X-class) flare events observed by the TRACE satellite and the Hinode/Solar Optical Telescope from 1998 May to 2009 May, we choose the event displaying one of the flare ribbons that completely sweeps across the umbra of a main sunspot of th…
The Two Integral X-Ray Transients IGR J17091-3624 and IGR J17098-3628: A Multiwavelength Long-Term Campaign
Hill, A. B.; Giroletti, M.; Capitanio, F. +7 more
IGR J17091-3624 and IGR J17098-3628 are two X-ray transients discovered by INTEGRAL and classified as possible black hole candidates. We present here the results obtained from the analysis of multiwavelength data sets collected by different instruments from 2005 until the end of 2007 on both sources. IGR J17098-3628 has been regularly detected by …
An XMM-Newton Spectral and Timing Study of IGR J16207 - 5129: An Obscured and Non-Pulsating HMXB
Kaaret, Philip; Walter, Roland; Tomsick, John A. +3 more
We report on a ~12 hr XMM-Newton observation of the supergiant high-mass X-ray binary (HMXB) IGR J16207 - 5129. This is only the second soft X-ray (0.4-15 keV, in this case) study of the source since it was discovered by the International Gamma-Ray Astrophysics Laboratory satellite. The average energy spectrum is very similar to those of neutron s…