Search Publications
Cross-calibration of the X-ray instruments onboard the Chandra, INTEGRAL, RXTE, Suzaku, Swift, and XMM-Newton observatories using G21.5-0.9
Read, A. M.; Guainazzi, M.; Tsujimoto, M. +7 more
Context. For many years, X-ray astronomy missions have used the Crab nebula as a celestial calibration source for the X-ray flux and spectral shape. However, the object is often too bright for current and future missions equipped with instruments with improved sensitivity.
Aims: We use G21.5-0.9, a pulsar-wind nebula with a time-constant powe…
Planck early results. XIII. Statistical properties of extragalactic radio sources in the Planck Early Release Compact Source Catalogue
Kneissl, R.; Miville-Deschênes, M. -A.; Bernard, J. -P. +201 more
The data reported in Planck's Early Release Compact Source Catalogue (ERCSC) are exploited to measure the number counts (dN/dS) of extragalactic radio sources at 30, 44, 70, 100, 143 and 217 GHz. Due to the full-sky nature of the catalogue, this measurement extends to the rarest and brightest sources in the sky. At lower frequencies (30, 44, and 7…
Sulfur depletion in dense clouds and circumstellar regions. I. H2S ice abundance and UV-photochemical reactions in the H2O-matrix
Muñoz Caro, G. M.; Jiménez-Escobar, A.
Aims: This work aims to study the unexplained sulfur depletion observed toward dense clouds and protostars.
Methods: We made simulation experiments of the UV-photoprocessing and sublimation of H2S and H2S:H2O ice in dense clouds and circumstellar regions, using the InterStellar Astrochemistry Chamber (ISA…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. IX. Time delays, lens dynamics and baryonic fraction in HE 0435-1223
Magain, P.; Koleva, M.; Faure, C. +13 more
We present accurate time delays for the quadruply imaged quasar HE 0435-1223. The delays were measured from 575 independent photometric points obtained in the R-band between January 2004 and March 2010. With seven years of data, we clearly show that quasar image A is affected by strong microlensing variations and that the time delays are best expr…
Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources
Kneissl, R.; Miville-Deschênes, M. -A.; Bernard, J. -P. +246 more
Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ran…
Quantitative evidence of an intrinsic luminosity spread in the Orion nebula cluster
Robberto, M.; Da Rio, N.; Ricci, L. +3 more
Aims: We study the distribution of stellar ages in the Orion nebula cluster (ONC) using accurate HST photometry taken from HST Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the s…
Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150, and HD 46966
Auvergne, M.; Gosset, E.; Baudin, F. +15 more
Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars.
Aims: We analyse the CoRoT data corresponding to three hot O-ty…
The star cluster - field star connection in nearby spiral galaxies. II. Field star and cluster formation histories and their relation
Larsen, S. S.; Silva-Villa, E.
Context. Recent studies have started to cast doubt on the assumption that most stars are formed in clusters. Observational studies of field stars and star cluster systems in nearby galaxies can lead to better constraints on the fraction of stars forming in clusters. Ultimately this may lead to a better understanding of star formation in galaxies, …
High-frequency predictions for number counts and spectral properties of extragalactic radio sources. New evidence of a break at mm wavelengths in spectra of bright blazar sources
de Zotti, G.; Martínez-González, E.; Toffolatti, L. +1 more
We present models to predict high-frequency counts of extragalactic radio sources using physically grounded recipes to describe the complex spectral behaviour of blazars that dominate the mm-wave counts at bright flux densities. We show that simple power-law spectra are ruled out by high-frequency (ν ≥ 100 GHz) data. These data also strongly const…
Transiting exoplanets from the CoRoT space mission. XV. CoRoT-15b: a brown-dwarf transiting companion
Mazeh, T.; Aigrain, S.; Alonso, R. +46 more
We report the discovery by the CoRoT space mission of a transiting brown dwarf orbiting a F7V star with an orbital period of 3.06 days. CoRoT-15b has a radius of 1.12+0.30-0.15 {R}_Jup and a mass of 63.3 ± 4.1 {M}_Jup, and is thus the second transiting companion lying in the theoretical mass domain of brown dwarfs. CoRoT-15b …