Search Publications
The nature of the high Galactic latitude O-star HD 93521: new results from X-ray and optical spectroscopy
Morel, T.; Rauw, G.; Palate, M.
Context. Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5 Vp object HD 93521 is still uncertain.
Aims: We have collected X-ray and optical observations to characterize the star and its surroundings.
Methods: X-ray images and spectra are analysed to search for traces of a recent star formation…
NGC 3627: a galaxy-dwarf collision?
Bomans, D. J.; Weżgowiec, M.; Soida, M.
Context. Group galaxies very often show distinct signs of interaction with both companion galaxies and the intragroup medium. X-ray observations are particularly helpful because they provide information on the temperatures and the densities of the hot gas in galaxies and intergalactic space. This can put important constraints on the nature and tim…
Microwave and radio emission of dusty star-forming galaxies: implication for the cosmic radio background
Lagache, G.; Ysard, N.
We use the most up-to-date cosmological evolution models of dusty star-forming galaxies and radio sources to compute the extragalactic number counts and the cosmic background from 408 MHz to 12 THz (or 24 µm). The evolution model of star-forming galaxies reproduces the recent constraints obtained by Spitzer, Herschel, and ground-based submm …
Weak G-band stars on the H-R diagram: clues to the origin of the Li anomaly
Jasniewicz, G.; Parthasarathy, M.; Palacios, A. +1 more
Aims: Weak G-band (WGB) stars are a rare class of cool luminous stars that present a strong depletion in carbon, but also lithium abundance anomalies that have been little explored in the literature since the first discovery of these peculiar objects in the early 1950s. Here we focus on the Li-rich WGB stars and report on their evolutionary s…
Large distance of ɛ Aurigae inferred from interstellar absorption and reddening
Wolf, M.; Harmanec, P.; Zasche, P. +9 more
The long-period (P = 27.1 years) peculiar eclipsing binary ɛ Aur, which has recently completed its two year-long primary eclipse, has perplexed astronomers for over a century. The eclipse arises from the transit of a huge, cool and opaque, disk across the face of the F0 Iab star. One of the principal problems with understanding this binary is that…
Spectropolarimetric signatures of anisotropic velocity distributions of optically thin coronal UV lines
Khan, A.; Landi Degl'Innocenti, E.
Context. Many interpretations of observations with the Ultraviolet Coronagraph Spectrometer (UVCS) operating aboard the Solar and Heliospheric Observatory (SOHO) have suggested that there are variations in particle velocity distributions. In this paper, we investigate their spectropolarimetric signatures.
Aims: We uncover the spectropolarimet…
Probing cluster dynamics in RXC J1504.1-0248 via radial and two-dimensional gas and galaxy properties
Klein, M.; Schneider, P.; Verdugo, M. +1 more
We study one of the most X-ray luminous cluster of galaxies in the REFLEX survey, RXC J1504.1-0248 (hereafter R1504; zcl = 0.2153), using XMM-Newton X-ray imaging spectroscopy, VLT/VIMOS optical spectroscopy, and WFI optical imaging. The mass distributions were determined using both the so-called hydrostatic method with X-ray imaging sp…
Staring at 4U 1909+07 with Suzaku
Wilms, J.; Pottschmidt, K.; Fürst, F. +4 more
We present an analysis of the neutron star high mass X-ray binary (HMXB) 4U 1909+07 mainly based on Suzaku data. We extend the pulse period evolution, which behaves in a random-walk like manner, indicative of direct wind accretion. Studying the spectral properties of 4U 1909+07 between 0.5 to 90 keV we find that a power-law with an exponential cut…
The magnetar candidate AX J1818.8-1559
Tiengo, A.; Götz, D.; Mereghetti, S. +3 more
In October 2007, a hard X-ray burst was detected by the INTEGRAL satellite from a direction consistent with the position of AX J1818.8-1559, an X-ray source at low Galactic latitude discovered with the Advanced Satellite for Cosmology and Astrophysics (ASCA) satellite in 1996-1999. The short duration (0.8 s) and soft spectrum (power-law photon ind…
The nature of the multi-wavelength emission of 3C 111
Beckmann, V.; Mattana, F.; de Jong, S.
Aims: We attempt to determine the nature of the high energy emission of the radio galaxy 3C 111, by distinguishing between the effects of the thermal and non-thermal processes.
Methods: We study the X-ray spectrum of 3C 111 between 0.4 keV and 200 keV, and its spectral energy distribution, using data from the Suzaku satellite combined wi…