Search Publications
ISOGAL-DENIS detection of red giants with weak mass loss in the Galactic bulge
Price, S. D.; Alard, C.; Blommaert, J. A. D. L. +21 more
The ISOGAL project is a survey of the stellar populations, structure, and recent star formation history of the inner disk and bulge of the Galaxy. ISOGAL combines 15 mu m and 7 mu m ISOCAM observations with DENIS IJK_s data to determine the nature of a source and the interstellar extinction. In this paper we report an ISOGAL study of a small field…
Carbon dioxide-methanol intermolecular complexes in interstellar grain mantles
Ehrenfreund, P.; Dartois, E.; Demyk, K. +1 more
We present new laboratory data to interpret the Infrared Space Observatory (ISO) spectra of protostellar objects, and particularly RAFGL7009S. Our experimental results show that solid methanol and carbon dioxide exhibit specific intermolecular interactions. We propose the formation of a Lewis acid-base complex between carbon dioxide and methanol m…
Multiplicity of the HH 111 jet source: it Hubble Space Telescope NICMOS images and VLA maps
Bally, John; Rodríguez, Luis F.; Reipurth, Bo +2 more
We have observed the region around the HH 111 jet source with NICMOS onboard the Hubble Space Telescope, using two filters, F160W and F205W, which besides stellar continuum transmit the [FeII] 1.64 mu m and H_2 2.12 mu m emission lines, respectively. The jet can now be traced to within 2\farcs4 of the VLA source. In the F205W filter we detect for …
TT Arietis: the low state revisited
Gänsicke, B. T.; Beuermann, K.; Sion, E. M. +3 more
We present optical and ultraviolet spectroscopy of TT Ari obtained during the 1982-85 low state. In November/December 1983, accretion had almost completely ceased, unveiling both the white dwarf and the secondary star. The IUE spectrum obtained during that occasion contains absorption lines of Lyalpha , \Si IV, \C IV, and \He II. We derive a photo…
What heats the bright H II regions in I ZW 18?
Schaerer, D.; Stasińska, G.
We have used the radiation field from a starburst population synthesis model appropriate for the brightest H ii region of I Zw 18 to perform a photoionization model analysis of this object. We have investigated whether, with the observed nebular density distribution as revealed by the HST images and a total stellar radiation compatible with the ob…
Detection of C_2H_4 in Neptune from ISO/PHT-S observations
Lellouch, E.; Atreya, S. K.; Schulz, B. +3 more
The 6-12 mu m spectrum of Neptune has been recorded with the PHT-S instrument of the Infrared Space Observatory (ISO) at a resolution of 0.095 mu m. In addition to the emissions of CH_4, CH_3D and C_2H_6 previously identified, the spectrum shows the first firm identification of ethylene C_2H_4. The inferred column density above the 0.2-mbar level …
High-resolution abundance analysis of two individual stars of the bulge globular cluster NGC 6553
Bica, E.; Barbuy, B.; Ortolani, S. +2 more
A detailed abundance analysis of 2 giants of the metal-rich bulge globular cluster NGC 6553 was carried out using high resolution échelle spectra obtained at the ESO 3.6m telescope. The temperature calibration of metal-rich cool giants needs high quality photometric data. We have obtained JK photometry at ESO and VI photometry with the Hubble Spac…
The local stellar velocity distribution of the Galaxy. Galactic structure and potential
Bienaymé, O.
The velocity distribution of neighbouring stars is deduced from the Hipparcos proper motions. We have used a classical Schwarzschild decomposition and also developed a dynamical model for quasi-exponential stellar discs. This model is a 3-D derivation of Shu's model in the framework of Stäckel potentials with three integrals of motion. We determin…
Chemical evolution of carbonaceous materials in the last stages of stellar evolution
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce J.
The out-of-plane bending modes of aromatic C-H bond at 11.3, 12.1, 12.4, and 13.3 mu m were detected in the ISO SWS spectra of the proto-planetary nebulae IRAS 07134+1005 and IRAS 22574+6609. In addition, unidentified emission features at 17.8, 18.9, and 19.1 mu m were detected in the SWS01 and SWS06 spectra of IRAS 07134+1005. The similar strengt…
Probing early-type galaxy evolution with the Kormendy relation
Greggio, L.; Saglia, R. P.; Bender, R. +3 more
We investigate the evolution of early-type galaxies in four clusters at z=0.4 (Abell 370, Cl 0303+17, Cl 0939+47 and Cl 1447+26) and in one at z=0.55 (Cl 0016+16). The galaxies are selected according to their spectrophotometrically determined spectral types and comprise the morphological classes E, S0 and Sa galaxies. Structural parameters are det…