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Hubble Space Telescope STIS Spectroscopy of Long-Period Dwarf Novae in Quiescence
Szkody, Paula; Sion, Edward M.; Godon, Patrick +5 more
We present the results of a synthetic spectral analysis of HST STIS spectra of five long-period dwarf novae obtained during their quiescence to determine the properties of their white dwarfs, which are little known for systems above the CV period gap. The five systems, TU Men, BD Pav, SS Aur, TT Crt, and V442 Cen, were observed as part of an HST S…
Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-Ray Emission Profiles
Isobe, Naoki; Hoshino, Akio; Sato, Kosuke +14 more
The compact group of galaxies HCG 62(z = 0.0145) was observed for 120ks with Suzaku XIS and HXD-PIN. The XIS spectra for four annular regions were fitted with a two-temperature vapec model with variable abundance, combined with the foreground Galactic component. The Galactic component was described by a two-temperature apec model, and constrained …
Condensation in Titan's stratosphere during polar winter
Irwin, P. G. J.; Teanby, N. A.; de Kok, R.
In Titan's north polar region stratospheric clouds are expected to form due to a combination of low temperatures and downward motion of volatile-enriched air. Here we investigate possible sources of stratospheric clouds at Titan's pole using data from the Cassini Composite Infrared Spectrometer and a simple condensation model. An upper limit for C…
Infrared to X-ray observations of PKS 2155-304 in a low state
Maraschi, L.; Covino, S.; Tagliaferri, G. +14 more
Aims: Our goal is to understand the nature of blazars and the mechanisms for the generation of high-energy γ-rays, through the investigation of the prototypical blazar PKS 2155{-}304, which shows complex behaviour.
Methods: We analyze simultaneous infrared-to-X-ray observations obtained with XMM-Newton and REM on November 7, 2006, when the sou…
High-energy X-ray spectra of Seyferts and Unification schemes for active galactic nuclei
Done, Chris; Middleton, Matthew; Schurch, Nick
The Unified Model of active galactic nuclei (AGN) predicts that the sole difference between type 1 and 2 Seyfert galaxies nuclei is the viewing angle with respect to an obscuring structure around the nucleus. High-energy photons above 20 keV are not affected by this absorption if the column is Compton thin, so their 30-100 keV spectra should be th…
The Evolution of Circumstellar Disks in Ophiuchus Binaries
Jensen, E. L. N.; Patience, J.; Akeson, R. L.
Four Ophiuchus binaries, two Class I systems and two Class II systems, with separations of ~450-1100 AU, were observed with the Owens Valley Radio Observatory (OVRO) millimeter interferometer. In each system, the 3 mm continuum maps show dust emission at the location of the primary star, but no emission at the position of the secondary. This resul…
A Hard X-Ray View of Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113
Reimer, A.; Reimer, O.; Costamante, L. +2 more
TeV blazars are known as prominent nonthermal emitters across the entire electromagnetic spectrum with their photon power peaking in the X-ray and TeV bands. If distant, absorption of γ-ray photons by the extragalactic background light (EBL) alters the intrinsic TeV spectral shape, thereby affecting the overall interpretation. Suzaku observations …
Orbital Parameters and Chemical Composition of Four White Dwarfs in Post-Common-Envelope Binaries
Vennes, Stéphane; Lanz, Thierry; Chayer, Pierre +2 more
We present FUSE observations of the hot white dwarfs in the post-common-envelope binaries Feige 24, EUVE J0720-317, BPM 6502, and EUVE J2013+400. The spectra show numerous photospheric absorption lines, which trace the white dwarf orbital motion. We report the detection of C III, O VI, P V, and Si IV in the spectra of Feige 24, EUVE J0720-317, and…
Star cluster versus field star formation in the nucleus of the prototype starburst galaxy M 82
de Grijs, R.; Cerviño, M.; Barker, S.
We analyse high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging of the nuclear starburst region of M 82, obtained as part of the Hubble Heritage mosaic made of this galaxy, in four filters (Johnson-Cousins equivalent B, V, and I broad bands, and an Hα narrow-band filter), as well as subsequently acquired U-band images. We fin…
Time variability of X-ray sources in the M 31 centre field
Stiele, H.; Pietsch, W.; Haberl, F. +1 more
Aims:We present an extension to our XMM-Newton X-ray source catalogue of
Methods: As a source list we used our extended ca…