Search Publications
Energy Crisis in the Superbubble DEM L192 (N51D)
Guerrero, Martín A.; Chu, You-Hua; Chen, C. -H. Rosie +2 more
Superbubbles surrounding OB associations provide ideal laboratories in which to study the stellar energy feedback problem, because the stellar energy input can be estimated from the observed stellar content of the OB associations, and the interstellar thermal and kinetic energies of superbubbles are well defined and easy to observe. We have used D…
Activity-related Changes in Local Solar Acoustic Mode Parameters from Michelson Doppler Imager and Global Oscillations Network Group
Howe, R.; Hill, F.; Hindman, B. W. +2 more
We use the ring-diagram technique of local helioseismology to study the amplitude and line width of high-degree solar acoustic modes from 474 days of data from the Michelson Doppler Imager Dynamics program, covering the period 1996-2002. The 2002 data are compared with contemporaneous data from the Global Oscillations Network Group network. The re…
Is M82 X-1 Really an Intermediate-Mass Black Hole? X-Ray Spectral and Timing Evidence
Titarchuk, Lev; Fiorito, Ralph
Ultraluminous X-ray sources (ULXs) with apparent luminosities up to hundreds of times the Eddington luminosity for a neutron star have been discovered in external galaxies. The existence of intermediate-mass black holes has been proposed to explain these sources. We present evidence for an intermediate-mass black hole in the ULX M82 X-1 based on t…
X-Ray Pulsars in the Small Magellanic Cloud
Lamb, R. C.; Macomb, D. J.; Majid, W. A.
XMM-Newton archival data for the Small Magellanic Cloud have been examined for the presence of previously undetected X-ray pulsars. One such pulsar, with a period of 202 s, is detected. Its position is consistent with an early B star in the SMC, and we identify it as a high-mass X-ray binary (HMXB). In the course of this study we determined the pu…
Detection of Hard X-Ray Emission from the Galactic Nuclear Region with INTEGRAL
Goldoni, P.; Parmar, A. N.; Ubertini, P. +13 more
This Letter presents the first results of an observational campaign to study the Galactic center with INTEGRAL, the International Gamma-Ray Astrophysics Laboratory. Mosaicked images were constructed using data obtained with ISGRI, the soft gamma-ray instrument of the coded aperture IBIS imager, in the energy ranges 20-40 and 40-100 keV. These give…
Chandra and XMM-Newton Observations of the Double Cluster A1758
David, Laurence P.; Kempner, Joshua
A1758 was classified by Abell as a single rich cluster of galaxies, but a ROSAT observation showed that this system consists of two distinct clusters (A1758N and A1758S) separated by approximately 8' (a projected separation of 2 Mpc in the rest frame of the clusters). Only a few galaxy redshifts have been published for these two clusters, but the …
Hydromagnetic Wave Excitation Upstream of an Interplanetary Traveling Shock
Klecker, B.; Wimmer-Schweingruber, R. F.; Hilchenbach, M. +5 more
Using data of the Highly Suprathermal Time-Of-Flight sensor of the Charge, Element, and Isotope Analysis System on board the Solar and Heliospheric Observatory spacecraft located at Lagrangian point L1 near Earth, we have measured proton spectra in the energy range 60 keV-2 MeV associated with the Bastille Day coronal mass ejection of 2000 July 14…
The Mass of the MACHO-LMC-5 Lens Star
Gould, Andrew; Bennett, David P.; Alves, David R.
We combine the available astrometric and photometric data for the 1993 microlensing event MACHO-LMC-5 to measure the mass of the lens, M=0.097+/-0.016Msolar. This is the most precise direct mass measurement of a single star other than the Sun. In principle, the measurement error could be reduced as low as 10% by improving the trigonomet…
Internal Color Properties of Resolved Spheroids in the Deep Hubble Space Telescope Advanced Camera for Surveys Field of UGC 10214
Ford, H. C.; Infante, L.; Zheng, W. +31 more
We study the internal color properties of a morphologically selected sample of spheroidal galaxies taken from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Early Release Observation program of UGC 10214 (``the Tadpole''). By taking advantage of the unprecedented high resolution of the ACS in this very deep data set, we are abl…
Magnetic Field, Hα, and RHESSI Observations of the 2002 July 23 Gamma-Ray Flare
Krucker, Säm; Wang, Haimin; Yurchyshyn, Vasyl +2 more
In this paper we examine two aspects of the 2002 July 23 gamma-ray flare by using multiwavelength observations. First, the data suggest that the interaction of the erupted field with an overlying large-scale coronal field can explain the offset between the gamma-ray and the hard X-ray sources observed in this event. Second, we pay attention to rap…