Search Publications
VLBI imaging of the gravitational lens MG J0414+0534
Ros, E.; Alberdi, A.; Pérez-Torres, M. A. +5 more
We observed the quadruple gravitationally lensed image of MG J0414+0534 on 23 November 1997 with a global VLBI array at 8.4 GHz. We report wide-field imaging results of its four components at submilliarcsecond resolution, displaying complex core-like and jet-like extended structures. A simple model combining a singular isothermal ellipsoid to repr…
ROSAT PSPC observations of T Tauri stars in MBM12 PSPC observations of T Tauri stars in MBM12
Neuhäuser, R.; Alcalá, J. M.; Stelzer, B. +4 more
We present the ROSAT PSPC pointed and ROSAT All-Sky Survey (RASS) observations and the results of our low and high spectral resolution optical follow-up observations of the T Tauri stars (TTS) and X-ray selected T Tauri star candidates in the region of the high galactic latitude dark cloud MBM12 (L1453-L1454, L1457, L1458). Previous observations h…
Lithium and rotation on the subgiant branch. II. Theoretical analysis of observations
de Laverny, P.; De Medeiros, J. R.; Charbonnel, C. +2 more
Lithium abundances and rotation, determined for 120 subgiant stars in Lèbre et al. (1999) are analyzed. To this purpose, the evolutionary status of the sample as well as the individual masses have been determined using the HIPPARCOS trigonometric parallax measurements to locate very precisely our sample stars in the HR diagram. We look at the dist…
On the possibility of ground-based direct imaging detection of extra-solar planets: the case of TWA-7
Neuhäuser, R.; Huélamo, N.; Brandner, W. +5 more
We show that ground-based direct imaging detection of extra-solar planets is possible with current technology. As an example, we present evidence for a possible planetary companion to the young T Tauri star 1RXSJ104230.3-334014 (=TWA-7), discovered by ROSAT as a member of the nearby TW Hya association. In an HST NICMOS F160W image, an object is de…
ISO-SWS observations of pure rotational H_2O absorption lines toward Orion-IRc2
de Graauw, Th.; Feuchtgruber, H.; van Dishoeck, E. F. +4 more
First detections of thermal water vapor absorption lines have been made toward Orion IRc2 using the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). Grating spectra covering wavelengths 25-45 mu m yield 19 pure rotational lines, originating from energy levels 200-750 K above ground. Fabry-Perot spectra of 5 transi…
Astrometric radial velocities. II. Maximum-likelihood estimation of radial velocities in moving clusters
Lindegren, Lennart; Madsen, Søren; Dravins, Dainis
Accurate proper motions and trigonometric parallaxes of stars in nearby open clusters or associations permit to determine their space motions relative to the Sun, without using spectroscopy for their radial-velocity component. This assumes that the member stars share the same mean velocity vector, apart from a (small) random velocity dispersion. W…
HD 209458 planetary transits from Hipparcos photometry
Arenou, F.; Robichon, N.
During its 39-month mission, Hipparcos observed the star {{
LWS spectroscopy of the luminous blue compact galaxy Haro 11
Östlin, G.; Bergvall, N.; Cernicharo, J. +1 more
We present the results of far infrared (FIR) spectroscopy of the luminous blue compact galaxy (BCG)
The Galactic warp in OB stars from Hipparcos
Lattanzi, M. G.; Drimmel, R.; Smart, R. L.
The kinematics of distant OB stars perpendicular to the Galactic plane, inferred from proper motions in the Hipparcos catalogue, are analysed and compared to the kinematic signature that would be induced by a long-lived Galactic warp. Previously we reported that the kinematics of the OB stars toward the anticenter were inconsistent with the assump…
Large [O]/[CO] ratios in cold molecular clouds towards W 49N
Ceccarelli, C.; Caux, E.; Vastel, C. +3 more
We present ISO-LWS high spectral resolution (R ~ 104) observations of the [OI] 63 mu m and 145 mu m lines towards the high mass star formation region W49N. At 145 mu m the observed spectrum shows an emission component only, while at 63 mu m it shows both emission and absorption components. We performed an analysis of the observed spectr…