Search Publications
Jupiter's hydrocarbons observed with ISO-SWS: vertical profiles of C_2H_6 and C_2H_2, detection of CH_3C_2H
Lellouch, E.; Encrenaz, T.; Feuchtgruber, H. +3 more
We have analysed the ISO-SWS spectrum of Jupiter in the 12-16 mum range, where several hydrocarbons exhibit rovibrational bands. Using temperature information from the methane and hydrogen emissions, we derive the mixing ratios (q) of acetylene and ethane at two independent pressure levels. For acetylene, we find q=(8.9+1.1-0.6
Adaptive optics images at 3.5 and 4.8 µ m of the core arcsec of NGC 1068: more evidence for a dusty/molecular torus
Alloin, D.; Marco, O.
Adaptive optics observations of NGC 1068 have allowed us to reach with a 4 m class telescope, diffraction-limited images at 3.5 µm (FWHM=0.24'') and 4.8 µm (FWHM=0.33'') of the central arcsec region. These observations reveal the presence of an unresolved core (radius less than 8 pc at Half Maximum) and an 80 pc sized ``disc-like'' str…
Observation of the origin of CMEs in the low corona
Delaboudinière, J. -P.; Lamy, P.; Delannée, C.
The aim of the main observing program with EIT on board SOHO, is to monitor the whole Sun surface in the Fe xii emission line at 195 Ä, every 17 minutes. The very beginning of some CMEs can be observed. We interpret Fe xii images in conjunction with He ii, Hα and coronagraph observations over a period of 6 days. We find that 7 prominences produced…
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 {{