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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…
Intrinsic Absorption in the Spectrum of Markarian 279: Simultaneous Chandra, FUSE, and STIS Observations
Kaiser, Mary Elizabeth; Green, Richard F.; Scott, Jennifer E. +12 more
We present a study of the intrinsic X-ray and far-ultraviolet absorption in the Seyfert 1.5 galaxy Markarian 279 using simultaneous observations from the Chandra X-ray Observatory, the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, and the Far Ultraviolet Spectroscopic Explorer (FUSE). We also present FUSE observations mad…
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…
Multi-wavelength study of a high-latitude EUV filament
Heinzel, Petr; Schmieder, Brigitte; Schwartz, Pavol +1 more
A large filament was observed during a multi-wavelength coordinated campaign on June 19, 1998 in the Hα line with the Swedish Vacuum Solar Telescope (SVST) at La Palma, in the coronal lines Fe ix/x 171 Å and Fe xi 195 Å with the Transition Region and Coronal Explorer (TRACE) and in EUV lines with the SOHO/CDS spectrometer and the hydrogen Lyman se…
Phase-Resolved Spectroscopy of Geminga Shows Rotating Hot Spot(s)
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +2 more
Isolated neutron stars are seen in x-rays through their nonthermal and/or surface thermal emissions. X-ray Multimirror Mission-Newton observations of the Geminga pulsar show a 43-electron volt spectrum from the whole neutron star surface, as well as a power-law component above 2 kiloelectron volts. In addition, we have detected a hot (170 electron…
Measuring Stellar Differential rotation with asteroseismology
Solanki, Sami K.; Gizon, Laurent
The variation of rotation with latitude is poorly known on stars other than the Sun. Several indirect techniques, photometric and spectroscopic, have been used to search for departure from rigid rotation for sufficiently fast rotators. Here we investigate the possibility of measuring stellar differential rotation for solar-type stars through aster…
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…
η Carinae's Brightness Variations Since 1998: Hubble Space Telescope Observations of the Central Star
Martin, J. C.; Koppelman, M. D.
We have measured the brightness variations in η Carinae for the past 6 years using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph and Advanced Camera for Surveys. Unlike ground-based data, observations by the HST allow direct measurement of the brightness of the central star by resolving it from the surrounding bright ejecta…
Three-fluid model of the heating and acceleration of the fast solar wind
Ofman, L.
A new three-fluid, two-dimensional, wave-driven model that includes, for the first time, heat conduction, viscous, and resistive dissipation for protons and electrons in two-dimensional coronal hole is presented. The fast solar wind model includes electron, proton, and He++ or O5+ ion fluids. The heating of the solar wind pla…
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 …