Search Publications
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…
Constraints on the abundance of solid O_2 in dense clouds from ISO-SWS and ground-based observations
Burgdorf, M.; van Dishoeck, E. F.; Whittet, D. C. B. +9 more
The Short Wavelength Spectrometer (SWS) on-board the Infrared Space Observatory (ISO) has been used to search for solid O_2 in cold dense clouds at 6.45 mu m. Additional constraints on the O_2 abundance are obtained from analysis of the 4.67 mu m solid CO absorption profile observed from the ground. We derive upper limits of 50% and 100% of solid …
Infrared spectroscopy of young supernova remnants heavily interacting with the interstellar medium. I. Ionized species in RCW 103
Lutz, D.; Sturm, E.; Oliva, E. +2 more
ISO spectral observations of the supernova remnant RCW103 are presented. This object is the prototype of relatively young remnants ( ~ 10(3) yr) with fast shocks (v_s ~ 1000 km s(-1) ) interacting with dense interstellar medium. The spectrum is dominated by prominent lines of [NeII], [SiII], [FeII] and other low excitation species which provide, f…