Search Publications
Weak-line T Tauri stars: circumstellar disks and companions. I. Spectral energy distributions and infrared excesses
Ray, T. P.; Gras-Velázquez, À.
We have analysed new infrared photometric data taken by the Infrared Space Observatory, in combination with 2MASS data where available, of 12 weak-line T Tauri stars (WTTS), belonging to different molecular clouds. A control study of 6 classical T Tauri stars (CTTS) for comparison with IRAS data has also been made. WTTS traditionally are not expec…
Can surface magnetic fields reproduce solar irradiance variations in cycles 22 and 23?
Solanki, S. K.; Krivova, N. A.; Wenzler, T.
Total solar irradiance is reconstructed using data from the spectromagnetograph on Kitt Peak for 1992 2003 (covering parts of cycles 22 and 23) and compared with observational data. The model assumes that solar irradiance variations are caused by surface magnetism and its single free parameter is kept at the same value for both cycles. A good corr…
INTEGRAL observation of V 0332+53 in outburst
Santangelo, A.; Walter, R.; Mowlavi, N. +9 more
We present the analysis of a 100 ks INTEGRAL (3-100 keV) observation of the transient X-ray pulsar V 0332+53in outburst. The source is pulsating at PPulse=4.3751±0.0002 s with a clear double pulse from 6 keVto 60 keV. The average flux was ~550 mCrab between 20 keVand 60 keV. We modeled the broad band continuum from 5 keVto 100 keVwith a…
High mass X-ray binaries in the LMC: Dependence on the stellar population age and the ``propeller'' effect
Gilfanov, M.; Shtykovskiy, P.
We study the population of compact X-ray sources in the Large Magellanic Cloud using the archival data of the XMM-Newton observatory. The total area of the survey is ≈ 3.8 square degrees with a limiting sensitivity of ≈10-14 erg/s/cm2, corresponding to a luminosity of ≈3× 1033 erg/s at the LMC distance. Out of ∼460…
Stephan's Quintet with XMM-Newton
Pietsch, W.; Breitschwerdt, D.; Trinchieri, G. +1 more
The prototype compact group known as Stephan's Quintet (SQ) was observed with XMM-Newton in order to complement the excellent resolution of Chandra with high sensitivity to extended emission. SQ is a dynamic environment whose main effect, at both X-ray and optical wavelengths, appears to be ISM stripping. This is manifested by: 1) secular evolutio…
Identification of the optical counterparts of high-mass X-ray binaries through optical photometry and spectroscopy
Reig, P.; Negueruela, I.; Manousakis, A. +2 more
We present the results of our search for optical counterparts to high-mass X-ray transient sources discovered by various X-ray missions. We obtained CCD images of the X-ray fields through BVR and Hα filters to identify early-type stars in the R-Hα versus B-V colour-colour diagram. We also obtained medium-resolution spectroscopy of the candidates i…
XMM-Newton timing mode observations of Mrk 421
Haberl, F.; Papadakis, I. E.; Brinkmann, W. +2 more
We present the results of a detailed temporal analysis of the bright BL Lac object Mrk 421 using the three available long timing mode observations by the EPIC PN camera. This detector mode is characterized by its long life time and is largely free of photon pile-up problems. The source was found in different intensity and variability states differ…
A new reduction of the raw Hipparcos data
van Leeuwen, F.; Fantino, E.
We present an outline of a new reduction of the Hipparcos astrometric data, the justifications of which are described in the accompanying paper. The emphasis is on those aspects of the data analysis that are fundamentally different from the ones used for the catalogue published in 1997. The new reduction uses a dynamical modelling of the satellite…
The low X-ray state of LS 5039 / RX J1826.2-1450
Motch, C.; Negueruela, I.; Martocchia, A.
Recent XMM-Newton and Chandra observations of the high mass X-ray binary LS 5039 / RX J1826.2-1450 caught the source in a faint X-ray state. In contrast with previous RXTE observations, we fail to detect any evidence of iron line emission. We also fail to detect X-ray pulsations. The X-ray spectrum can be well fitted by a simple powerlaw, slightly…
The XMM-LSS survey. The XMDS/VVDS 4σ catalogue
Maccagni, D.; Maraschi, L.; Chiappetti, L. +15 more
We present a first catalogue of X-ray sources resulting from the central area of the XMM-LSS (Large Scale Structure survey). We describe the reduction procedures and the database tools we developed and used to derive a well defined catalogue of X-ray sources. The present catalogue is limited to a sub-sample of 286 sources detected at 4 σ in the 1 …