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X-Ray Emission from the Old Pulsar B0950+08
Pavlov, George G.; Zavlin, Vyacheslav E.
We present the timing and spectral analyses of the XMM-Newton data on the 17 Myr old, nearby radio pulsar B0950+08. This observation revealed pulsations of the X-ray flux of PSR B0950+08 at its radio period, P~=253 ms. The pulse shape and pulsed fraction are apparently different at lower and higher energies of the observed 0.2-10 keV energy range,…
On the Lack of Thermal Emission from the Quiescent Black Hole XTE J1118+480: Evidence for the Event Horizon
McClintock, Jeffrey E.; Narayan, Ramesh; Rybicki, George B.
A soft component of thermal emission is very commonly observed from the surfaces of quiescent, accreting neutron stars. We searched with Chandra for such a surface component of emission from the dynamical black hole candidate XTE J1118+480 (=J1118), which has a primary mass M1~8 Msolar. None was found, as one would expect if …
The Redshift Distribution of Near-Infrared-Selected Galaxies in the Great Observatories Origins Deep Survey as a Test of Galaxy Formation Scenarios
Papovich, Casey; Dickinson, Mark; Somerville, Rachel S. +11 more
The redshift distribution of near-IR-selected galaxies is often used to attempt to discriminate between the classical view of galaxy formation, in which present-day luminous galaxies were assembled at early times and evolve through the passive aging of their stellar populations, and that of hierarchical structure formation, in which galaxies were …
A Strong, Broad Absorption Feature in the X-Ray Spectrum of the Nearby Neutron Star RX J1605.3+3249
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaplan, D. L. +2 more
We present X-ray spectra taken with XMM-Newton of RX J1605.3+3249, the third brightest in the class of nearby thermally emitting neutron stars. In contrast to what is the case for the brightest object, RX J1856.5-3754, we find that the spectrum of RX J1605.3+3249 cannot be described well by a pure blackbody, but shows a broad absorption feature at…
A Hard X-ray Survey of the Sagittarius Arm Tangent with the IBIS Telescope of the INTEGRAL Observatory: A Catalog of Sources
Sunyaev, R. A.; Postnov, K. A.; Cherepashchuk, A. M. +3 more
We analyze the images of the Sagittarius Arm tangent obtained with the IBIS telescope of the INTEGRAL observatory in the energy range 18-120 keV during its observations in the spring of 2003. We detected 28 sources at a statistically significant level with fluxes above 1.4 mCrab in the energy range 18-60 keV. Of these sources, 16 were previously i…
Quantitative Studies of the Far-Ultraviolet, Ultraviolet, and Optical Spectra of Late O- and Early B-Type Supergiants in the Magellanic Clouds
Hillier, D. J.; Crowther, P. A.; Evans, C. J. +1 more
We present quantitative studies of eight late O- and early B-type supergiants in the Magellanic Clouds using far-ultraviolet Far Ultraviolet Spectroscopic Explorer, ultraviolet International Ultraviolet Explorer/Hubble Space Telescope, and optical VLT-UVES spectroscopy. Temperatures, mass-loss rates, and CNO abundances are obtained using the non-L…
The Physical Properties and Effective Temperature Scale of O-Type Stars as a Function of Metallicity. I. A Sample of 20 Stars in the Magellanic Clouds
Massey, Philip; Pauldrach, A. W. A.; Bresolin, Fabio +2 more
We have obtained Hubble Space Telescope (HST) and ground-based observations of a sample of 20 O-type stars in the LMC and SMC, including six of the hottest massive stars known (subtypes O2-O3) in the R136 cluster. In general, these data include (1) the HST UV spectra in order to measure the terminal velocities of the stellar winds, (2) high signal…
Theory and Observations of Slow-Mode Solitons in Space Plasmas
Stasiewicz, K.
A generalized model for one-dimensional magnetosonic structures of large amplitude in space plasmas is presented. The model is verified with multipoint measurements on Cluster satellites in the magnetosheath and the boundary layer under conditions of plasma beta (plasma/magnetic pressure) between 0.1 10. We demonstrate good agreement between the m…
3D magnetic configuration of the Hα filament and X-ray sigmoid in NOAA AR 8151
Amari, T.; Régnier, S.
We investigate the structure and relationship of an Hα filament and an X-ray sigmoid observed in active region NOAA 8151. We first examine the presence of such structures in the reconstructed 3D coronal magnetic field obtained from the non-constant-α force-free field hypothesis using a photospheric vector magnetogram (IVM, Mees Solar Observatory).…
Cluster observations of lower hybrid turbulence within thin layers at the magnetopause
Wahlund, J. -E.; Fazakerley, A. N.; André, M. +3 more
We use data from the Cluster satellites to study waves in the frequency range of ~2-150 Hz at the magnetopause. In addition to broad band wave turbulence we identify lower hybrid drift waves and whistler waves. Wave amplitudes maximize within narrow current sheets that are associated with density gradients and electron beams and that can be the se…