Search Publications
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…
Evolutionary signatures in complex ejecta and their driven shocks
Farrugia, C.; Berdichevsky, D.
We examine interplanetary signatures of ejecta-ejecta interactions. To this end, two time intervals of inner-heliospheric (≤1AU) observations separated by 2 solar cycles are chosen where ejecta/magnetic clouds are in the process of interacting to form complex ejecta. At the Sun, both intervals are characterized by many coronal mass ejections (CMEs…
X-ray emission from the nuclei, lobes and hot-gas environments of two FR II radio galaxies
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M. +1 more
We report on the detection of multiple components of X-ray emission from the two FR II radio galaxies, 3C 223 and 3C 284, based on new XMM-Newton observations. We attribute the detected X-ray emission from the lobes of both sources to inverse-Compton scattering of cosmic microwave background photons. With this model, we find that the magnetic fiel…
The Globular Cluster Systems of Five Nearby Spiral Galaxies: New Insights from Hubble Space Telescope Imaging
Chandar, Rupali; Lee, Myung Gyoon; Whitmore, Bradley
We use available multifilter Hubble Space Telescope (HST) WFPC2 imaging of five (M81, M83, NGC 6946, M101, and M51, in order of distance) low-inclination, nearby spiral galaxies to study ancient star cluster populations. Combining rigorous selection criteria to reject contaminants (individual stars, background galaxies, and blends) with optical ph…
The diameter and evolutionary state of Procyon A. Multi-technique modeling using asteroseismic and interferometric constraints
Bordé, P.; Provost, J.; Berthomieu, G. +3 more
We report the angular diameter measurement obtained with the VINCI/VLTI instrument on the nearby star Procyon A (α CMi A, F5IV-V), at a relative precision of ± 0.9%. We obtain a uniform disk angular diameter in the K band of θUD = 5.376±0.047 mas and a limb darkened value of θLD = 5.448±0.053 mas. Together with the HIPPARCOS …