Search Publications
Discovery of a 7 mHz X-Ray Quasi-periodic Oscillation from the most Massive Stellar-mass Black Hole IC 10 X-1
Mushotzky, Richard F.; Pasham, Dheeraj R.; Strohmayer, Tod E.
We report the discovery with XMM-Newton of an ≈7 mHz X-ray (0.3-10.0 keV) quasi-periodic oscillation (QPO) from the eclipsing, high-inclination black hole binary IC 10 X-1. The QPO is significant at >4.33σ confidence level and has a fractional amplitude (% rms) and a quality factor, Q ≡ ν/Δν, of ≈11 and 4, respectively. The overall X-ray (0.3-1…
Cold Dust but Warm Gas in the Unusual Elliptical Galaxy NGC 4125
Clements, D. L.; Ciesla, L.; Boquien, M. +19 more
Data from the Herschel Space Observatory have revealed an unusual elliptical galaxy, NGC 4125, which has strong and extended submillimeter emission from cold dust but only very strict upper limits to its CO and H I emission. Depending on the dust emissivity, the total dust mass is 2-5 × 106 M ⊙. While the neutral gas-to-dust …
Hemispheric Asymmetries in the Polar Solar Wind Observed by Ulysses near the Minima of Solar Cycles 22 and 23
McComas, D. J.; Pogorelov, N. V.; Desai, M. I. +2 more
We examined solar wind plasma and interplanetary magnetic field (IMF) observations from Ulysses' first and third orbits to study hemispheric differences in the properties of the solar wind and IMF originating from the Sun's large polar coronal holes (PCHs) during the declining and minimum phase of solar cycles 22 and 23. We identified hemispheric …
Binary Frequencies in a Sample of Globular Clusters. I. Methodology and Initial Results
Bregman, Joel N.; Ji, Jun
Binary stars are thought to be a controlling factor in globular cluster evolution, since they can heat the environmental stars by converting their binding energy to kinetic energy during dynamical interactions. Through such interaction, the binaries determine the time until core collapse. To test predictions of this model, we have determined binar…
Simultaneous X-Ray and Radio Observations of Rotating Radio Transient J1819-1458
Rea, N.; Kramer, M.; McLaughlin, M. A. +4 more
We present the results of simultaneous radio and X-ray observations of PSR J1819-1458. Our 94 ks XMM-Newton observation of the high magnetic field (~5 × 1013 G) pulsar reveals a blackbody spectrum (kT ~ 130 eV) with a broad absorption feature, possibly composed of two lines at ~1.0 and ~1.3 keV. We performed a correlation analysis of th…
Herschel Observations Reveal Anomalous Molecular Abundances toward the Galactic Center
Lis, D. C.; Gerin, M.; Goicoechea, J. R. +4 more
We report the Herschel detections of hydrogen fluoride (HF) and para-water (p-H2O) in gas intercepting the sight lines to two well-studied molecular clouds in the vicinity of the Sgr A complex: G-0.02-0.07 (the "+50 km s-1 cloud") and G-0.13-0.08 (the "+20 km s-1 cloud"). Toward both sight lines, HF and water absor…
Comet 17P/Holmes: Contrast in Activity between before and after the 2007 Outburst
Hasegawa, Sunao; Usui, Fumihiko; Ootsubo, Takafumi +17 more
A Jupiter-family comet, 17P/Holmes, underwent outbursts in 1892 and 2007. In particular, the 2007 outburst is known as the greatest outburst over the past century. However, little is known about the activity before the outburst because it was unpredicted. In addition, the time evolution of the nuclear physical status has not been systematically st…
Another Brick in Understanding Chemical and Kinematical Properties of BSSs: NGC 6752
Dalessandro, E.; Mucciarelli, A.; Ferraro, F. R. +2 more
We used high-resolution spectra acquired with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to investigate the chemical and kinematical properties of a sample of 22 blue straggler stars (BSSs) and 26 red giant branch stars in the nearby globular cluster NGC 6752. We measured radial and rotational v…
Evidence of Non-thermal X-Ray Emission from HH 80
Miceli, M.; Bonito, R.; Albacete-Colombo, J. F. +4 more
Protostellar jets appear at all stages of star formation when the accretion process is still at work. Jets travel at velocities of hundreds of km s-1, creating strong shocks when interacting with the interstellar medium. Several cases of jets have been detected in X-rays, typically showing soft emission. For the first time, we report ev…
Tidal Tails of Minor Mergers. II. Comparing Star Formation in the Tidal Tails of NGC 2782
Knezek, Patricia M.; Charlton, Jane; Scowen, Paul +5 more
The peculiar spiral NGC 2782 is the result of a minor merger with a mass ratio ~4: 1 occurring ~200 Myr ago. This merger produced a molecular and H I-rich, optically bright eastern tail and an H I-rich, optically faint western tail. Non-detection of CO in the western tail by Braine et al. suggested that star formation had not yet begun. However, d…