Search Publications
Thermal properties of asteroid 21 Lutetia from Spitzer Space Telescope observations
Jorda, L.; Lamy, P. L.; Barucci, M. A. +3 more
Context. Asteroid 21 Lutetia is the second target of the Rosetta space mission with a flyby scheduled in July 2010. To best prepare the observational campaign, Lutetia is being extensively characterized by ground- and space-based astronomical facilities.
Aims: We used the Spitzer Space Telescope (SST) to determine the thermal properties of Lu…
The spectroscopic evolution of the symbiotic star AG Draconis. I. The O VI Raman, Balmer, and helium emission line variations during the outburst of 2006-2008
Wolf, M.; Bernabei, S.; Shore, S. N. +6 more
Context. AG Dra is one of a small group of low metallicity S-type symbiotic binaries with K-type giants that undergoes occasional short-term outbursts of unknown origin.
Aims: Our aim is to study the behavior of the white dwarf during an outburst using the optical Raman lines and other emission features in the red giant wind. The goal is to d…
The disk-bearing young star IM Lupi. X-ray properties and limits on accretion
Schmitt, J. H. M. M.; Güdel, M.; Günther, H. M. +3 more
Context. Classical T Tauri stars (CTTS) differ in their X-ray signatures from older pre-main sequence stars, e.g., weak-lined TTS (WTTS). CTTS exhibit a soft excess and deviations from the low-density coronal limit in the He-like triplets.
Aims: We test whether these features correlate with either accretion or the presence of a disk by observ…
Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI
Waters, L. B. F. M.; Menten, K. M.; Olofsson, H. +26 more
Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight.
Aims: We have aimed to elucidate the nature and structure of the VY CMa water vapour masers i…
Temporal downflows in a penumbra
Katsukawa, Y.; Jurčák, J.
Aims: We analyze temporal downflow patches that are located in a penumbra and have the same polarity of the magnetic field as a sunspot umbra.
Methods: The repetitive 2'' wide raster scans of penumbral regions that are taken with one minute cadence by the Hinode spectropolarimeter are used to detect the line-of-sight velocities in the pe…
The ISO Long Wavelength Spectrometer line spectrum of VY Canis Majoris and other oxygen-rich evolved stars
Menten, K. M.; White, G. J.; van der Tak, F. F. S. +1 more
Context. The far-infrared spectra of circumstellar envelopes around various oxygen-rich stars were observed using the ISO Long Wavelength Spectrometer (LWS). These have been shown to be spectrally rich, particularly in water lines, indicating a high H2O abundance.
Aims: We have examined high signal-to-noise ISO LWS observations of …
Total solar irradiance since 1996: is there a long-term variation unrelated to solar surface magnetic phenomena?
Steinhilber, F.
Context. Total solar irradiance (TSI) has been measured with space-based instruments since 1978. The TSI during the recent solar minimum in 2009 has been lower than the two former minima around the years 1986 and 1996, which points to a long-term decrease.
Aims: In this study, we address the question of whether the observed decrease in the TS…
Rotation and lithium abundance of solar-analog stars. Theoretical analysis of observations
de Medeiros, J. R.; da Costa, J. S.; Do Nascimento, J. D.
Context. Rotational velocity, lithium abundance, and the mass depth of the outer convective zone are key parameters in the study of the processes at work in the stellar interior, in particular when examining the poorly understood processes operating in the interior of solar-analog stars.
Aims: We investigate whether the large dispersion in th…
Interferometric radius and limb darkening of the asteroseismic red giant η Serpentis with the CHARA Array
Kervella, P.; Barban, C.; Mérand, A. +10 more
Context. The radius of a star is a very important constraint to evolutionary models, particularly when combined with asteroseismology. Diameters can now be measured interferometrically with great precision (better than 1%), but the center-to-limb darkening (CLD) remains a potential source of bias. Measuring this bias is possible by completely reso…
Herschel observations in the ultracompact HII region Mon R2. Water in dense photon-dominated regions (PDRs)
Boulanger, F.; Martin, P. G.; France, K. +42 more
Context. Monoceros R2, at a distance of 830 pc, is the only ultracompact H ii region (UC H ii) where the photon-dominated region (PDR) between the ionized gas and the molecular cloud can be resolved with Herschel. Therefore, it is an excellent laboratory to study the chemistry in extreme PDRs (G0 > 105 in units of Habing f…