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Coronal density diagnostics with Helium-like triplets: CHANDRA-LETGS observations of Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099
Schmitt, J. H. M. M.; Burwitz, V.; Raassen, A. J. J. +5 more
We present an analysis of ten cool stars (Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099) observed with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. This sample contains all cools stars observed with the LETGS presently available to us with integratio…
Asteroids as calibration standards in the thermal infrared for space observatories
Müller, T. G.; Lagerros, J. S. V.
Asteroids have been used extensively as calibration sources for the Infrared Space Observatory (ISO) and are planned to be used by future groundbased, airborne and space-based projects in the thermal infrared (IR) and in the sub-millimetre. We summarize the general IR observational parameters with a focus on space observatories and discuss brightn…
The ages of the globular clusters M 71 and 47 Tuc from Strömgren uvby photometry. Evidence for high ages
Grundahl, F.; Stetson, P. B.; Andersen, M. I.
New uvby CCD photometry for the fairly metal-rich globular clusters M 71 (NGC 6838) and 47 Tuc (NGC 104) is presented. We derive the cluster distances using a sample of field subdwarfs with metallicities determined from uvby photometry and accurate parallaxes from the Hipparcos mission. The biases associated with the main-sequence fitting techniqu…
Fast-rotating nearby solar-type stars, Li abundances and X-ray luminosities. I. Spectral classification, v sin i, Li abundances and X-ray luminosities
Tagliaferri, G.; Pasquini, L.; de Medeiros, J. R. +3 more
We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velociti…
Doppler Imaging of stellar magnetic fields. III. Abundance distribution and magnetic field geometry of alpha 2 CVn
Ilyin, I.; Piskunov, N.; Kochukhov, O. +2 more
We used the new magnetic Doppler Imaging code to reconstruct the magnetic field geometry and surface abundance distributions for the classical magnetic CP star alpha 2 CVn. High-resolution spectropolarimetric observations in the Stokes I and V parameters were collected with the SOFIN échelle spectrograph at the Nordic Optical Telescope.…
The relation of PAH strength with cold dust in galaxies
Bianchi, S.; Klaas, U.; Haas, M.
Mid-infrared spectra and submillimetre maps are investigated for five galaxies covering a range of star forming activity. We find a good spatial coincidence between the 850 mu m continuum emission and the strength of the PAH 7.7 mu m line. The PAH 7.7 mu m peak to 850 mu m flux ratio lies in the range around 2 with a moderate dispersion across the…
A search for solar g modes in the GOLF data
Baudin, F.; García, R. A.; Provost, J. +14 more
With over 5 years of GOLF data having some 90% continuity, a new attempt has been made to search for possible solar g modes. Statistical methods are used, based on the minimum of assumptions regarding the solar physics; namely that mode line-widths are small compared with the inverse of the observing time, and that modes are sought in the frequenc…
Two-dimensional electron density in the solar corona from inversion of white light images - Application to SOHO/LASCO-C2 observations
Lamy, P.; Quémerais, E.
We present here the inversion method which has been developed to derive the electron density in the Solar Corona from LASCO-C2 white light images. We discuss how our inversion scheme can be applied either to images of polarized brightness of the corona or images of total brightness after removal of the dust and stray light components. The outputs …
The XMM-Newton serendipitous survey . II. First results from the AXIS high galactic latitude medium sensitivity survey
Pérez-Fournon, I.; Motch, C.; Page, M. J. +25 more
We present the first results on the identifications of a medium sensitivity survey (X-ray flux limit 2x 10-14 erg cm-2 s-1 in the 0.5-4.5 keV band) at high galactic latitude ({\mid}b{\mid}>20deg) carried out with the XMM-Newton X-ray observatory within the AXIS observing programme. This study is being…
X-ray evidence for spectroscopic diversity of type Ia supernovae:. XMM observation of the elemental abundance pattern in M 87
Finoguenov, A.; Böhringer, H.; Arnaud, M. +2 more
We present the results of a detailed element abundance study of hot gas in M 87, observed by XMM-Newton. We choose two radial bins, 1'-3' and 8'-16' (8'-14' for EMOS; hereafter the central and the outer zones), where the temperature is almost constant, to carry out the detailed abundance measurements of O, Ne, Mg, Si, S, Ar, Ca, Fe and Ni using EP…