Search Publications
Obscuring clouds playing hide-and-seek in the active nucleus H0557-385
Bianchi, S.; Guainazzi, M.; Ballo, L. +2 more
This Letter reports on two XMM-Newton observations of the type 1 Seyfert galaxy H0557-385 obtained in 2006, which show the source at an historical low flux state, more than a factor of ~10 lower than a previous XMM-Newton look in 2002. The low flux spectrum presents a strong Fe Kα line associated with a Compton reflection continuum. An additional …
Spectro-Polarimetric Observations of Solar Magnetic Fields and the SOHO/MDI Calibration Issue
Balthasar, H.; Demidov, M. L.
Comparisons of solar magnetic-field measurements made in different spectral lines are very important, especially in those lines in which observations have a long history or (and) specific diagnostic significance. The spectral lines Fe I 523.3 nm and Fe I 525.0 nm belong to this class. Therefore, this study is devoted to a comprehensive analysis us…
Accretion Properties of a Sample of Hard X-Ray (<60 keV) Selected Seyfert 1 Galaxies
Wang, J.; Wei, J. Y.; Mao, Y. F.
We examine the accretion properties in a sample of 42 hard (3-60 keV) X-ray selected nearby broad-line active galactic nuclei (AGNs). The energy range in the sample is harder than that usually used in similar previous studies. These AGNs are mainly complied from the RXTE All Sky Survey, and complemented by the released INTEGRAL AGN catalog. The bl…
Accurate classification of 17 AGNs detected with Swift/BAT
Palazzi, E.; Minniti, D.; Masetti, N. +16 more
Through an optical campaign performed at 5 telescopes located in the northern and the southern hemispheres, plus archival data from two on line sky surveys, we have obtained optical spectroscopy for 17 counterparts of suspected or poorly studied hard X-ray emitting active galactic nuclei (AGNs) detected with Swift/BAT in order to determine or bett…
Titan ionospheric conductivities from Cassini measurements
Garnier, P.; Wahlund, J. -E.; Ågren, K. +6 more
We present the first results of ionospheric conductivities at Titan based on measurements during 17 Titan flybys from the Cassini spacecraft. We identify an ionospheric region ranging from 1450±95km (approximately the location of the exobase) to approximately 1000 km where electrical currents perpendicular to the magnetic field may become importan…
On the role of the post-starburst phase in the buildup of the red sequence of intermediate-redshift clusters
Smail, Ian; Milvang-Jensen, Bo; Zaritsky, Dennis +4 more
We present new deep spectroscopic observations of 0.05-0.5 L* galaxies in one cluster (cl1232.5-1250) drawn from the ESO (European Southern Observatory) Distant Cluster Survey (EDisCS) sample, at z = 0.54. The new data extend the spectroscopy already available for this cluster by about 1 mag. The cluster has a large fraction of passive …
A planet around the evolved intermediate-mass star HD 110014
Pasquini, L.; de Medeiros, J. R.; Hatzes, A. P. +5 more
Context: We found evidence for a sub-stellar companion around the K giant star HD 110014. This cool evolved star, with a spectral type K2III and an estimated mass between 1.9 and 2.4 M⊙, is slightly metal rich with [Fe/H] = 0.19 and a rotational velocity V sin i = 2.0 km s-1.
Aims: To search for extrasolar planets around …
The Radial Extent of the Double Subgiant Branch in NGC 1851
Rejkuba, M.; Zoccali, M.; Pancino, E. +3 more
Recent Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) observations revealed the presence of a double subgiant branch (SGB) in the core of the Galactic globular cluster NGC 1851. This peculiarity was tentatively explained by the presence of a second population with either an age difference of about 1 Gyr, or a higher C+N+O abundance…
XMM-Newton RGS spectrum of RX J0720.4-3125: an absorption feature at 0.57 keV
Haberl, F.; Neuhäuser, R.; Hohle, M. M. +2 more
Aims: By measuring the gravitational redshift of spectral features in the spectrum of thermal radiation emitted from neutron stars, useful constraints for the equation of state of superdense matter can be obtained via an estimate of the mass-to-radius ratio. We searched for spectral line features in the high-resolution X-ray spectrum of the isolat…
Conjugate ionospheric equivalent currents during bursty bulk flows
Nakamura, R.; Kauristie, K.; Amm, O. +1 more
Ionospheric equivalent currents related to bursty bulk flows (BBF) during Cluster and the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network conjunctions between 2001 and 2006 are studied. A geomagnetically southeast-northwest aligned, relatively narrow channel of northwestward equivalent current density with downwa…