Search Publications
Detailed study of the X-ray and optical/UV orbital ephemeris of X1822-371
Robba, N. R.; Papitto, A.; Burderi, L. +4 more
Aims: Recent studies of the optical/UV and X-ray ephemerides of X1822-371 have found some discrepancies in the value of the orbital period derivative. Because of the importance of this value in constraining the system evolution, we comprehensively analyse all the available optical/UV/X eclipse times of this source to investigate the origin of…
X-ray detected infrared excess AGN in the Chandra deep fields: a moderate fraction of Compton-thick sources
Comastri, A.; Georgantopoulos, I.; Rovilos, E. +2 more
We examine the properties of the X-ray-detected infrared excess AGN or dust obscured galaxies (DOGs) in the Chandra deep fields (CDFs). We find 26 X-ray-detected sources that obey the 24 µm to R-band flux ratio criterion f24/fR > 1000. These are at a median redshift of 2.3, while their IR luminosities are above 10
The two components of the evolved massive binary LZ Cephei. Testing the effects of binarity on stellar evolution
Bouret, J. -C.; Martins, F.; Donati, J. -F. +2 more
Aims: We present an in-depth study of the two components of the binary system LZ Cep to constrain the effects of binarity on the evolution of massive stars.
Methods: We analyzed a set of high-resolution, high signal-to-noise ratio optical spectra obtained over the orbital period of the system to perform a spectroscopic disentangling and …
HST/ACS color-magnitude diagrams of candidate intermediate-age M 31 globular clusters. The role of blue horizontal branches
Bellazzini, M.; Galleti, S.; Federici, L. +3 more
We present deep (V ≃ 28.0) BV photometry obtained with the wide field channel of the Advanced Camera for Surveys on board HST for four M 31 globular clusters that were identified as candidate intermediate-age (age ~ 1-9 Gyr) by various authors, based on their integrated spectra and/or broad/intermediate-band colors. Two of them (B292 and B350) dis…
A multi-epoch XMM-Newton campaign on the core of the massive Cygnus OB2 association
Rauw, G.
Context. Cyg OB2 is one of the most massive associations of O-type stars in our Galaxy. Despite the large interstellar reddening towards Cyg OB2, many studies, spanning a wide range of wavelengths, have been conducted to more clearly understand this association. X-ray observations provide a powerful tool to overcome the effect of interstellar abso…
Solar total irradiance in cycle 23
Solanki, S. K.; Schmutz, W.; Krivova, N. A.
Context. The most recent minimum of solar activity was deeper and longer than the previous two minima as indicated by different proxies of solar activity. This is also true for the total solar irradiance (TSI) according to the PMOD composite.
Aims: The apparently unusual behaviour of the TSI has been interpreted as evidence against solar surf…
X-ray wind tomography of the highly absorbed HMXB IGR J17252-3616
Walter, R.; Manousakis, A.
Context. About ten persistently highly absorbed super-giant high-mass X-ray binaries (sgHMXB) have been discovered by INTEGRAL as bright hard X-ray sources lacking bright X-ray counterparts. Besides IGR J16318-4848, which has peculiar characteristics, the other members of this family share many properties with the classical wind-fed sgHMXB systems…
Suzaku observation of the LINER NGC 4102
Esquej, P.; Ebrero, J.; Papadakis, I. +11 more
Context. Low-ionisation, nuclear emission-line region (LINER) nuclei are said to be different from other active galactic nuclei (AGN) due to the presence of complex absorbing structures along the line-of-sight and/or an inefficient mode of accretion onto the supermassive black hole. However, this is still open.
Aims: We investigate the broad …
New X-ray observations of IQ Aurigae and α2 Canum Venaticorum. Probing the magnetically channeled wind shock model in A0p stars
Schmitt, J. H. M. M.; Robrade, J.
Aims: We re-examine the scenario of X-ray emission from magnetically confined/channeled wind shocks (MCWS) for Ap/Bp stars, a model originally developed to explain the ROSAT detection of the A0p star IQ Aur.
Methods: We present new X-ray observations of the A0p stars α2 CVn (Chandra) and IQ Aur (XMM-Newton) and discuss our fin…
The large-scale diffuse radio emission in A781
Bonafede, A.; Govoni, F.; Giovannini, G. +2 more
Context. A781 belongs to a complex system characterized by extended X-ray emissions that may form part of line of clusters of galaxies along a filament.
Aims: The aim of this work is to investigate the possible presence of extended, diffuse synchrotron radio emission connected to the intra-cluster medium of A781.
Methods: We studied the …