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Infrared spectra of carbon stars observed by the ISO SWS. I. Molecular absorption in N-type and SC-type stars
Ohnaka, K.; Tsuji, T.; Aoki, W.
We carried out observations of bright optical carbon stars by the ISO SWS, and detected the absorption features of CO, CS, CH, SiS and HCN in N-type and SC-type stars. We found several characteristics of molecular absorption features corresponding to the spectral types. The CH fundamental bands in 3-4 mu m in N-type stars are stronger than those i…
Deep H-Band Galaxy Counts and Half-Light Radii from Hubble Space Telescope/NICMOS Parallel Observations
McCarthy, Patrick J.; Weymann, Ray J.; Yan, Lin +1 more
We present deep galaxy counts and half-light radii from F160W (λc=1.6 µm) images obtained with the Near-Infrared Camera and Multiobject Spectrograph on the Hubble Space Telescope. Nearly 9 arcmin2 have been imaged with camera 3, with 3 σ depths ranging from H=24.3 to 25.5 in a 0.6" diameter aperture. The slope of the co…
The kinematically peculiar cores of the Coma cluster early-type galaxies NGC 4816 and IC 4051
Saglia, R. P.; Bender, R.; Wegner, G. +1 more
The Coma cluster is one of the richest known cluster of galaxies, spanning about 4 dex in density. Hence it is the ideal place to study the structure of galaxies as a function of environmental density in order to constrain the theories of galaxy formation and evolution. For a magnitude limited sample of 35 E and S0 galaxies we obtained long slit s…
Infrared Imaging and Spectroscopy of the Helix with ISOCAM
Boulanger, F.; Bachiller, R.; Cernicharo, J. +8 more
We report infrared images of the Helix Nebula centered at 6.9 µm (LW2 filter) and 15 µm (LW3 filter) obtained with ISOCAM on board the Infrared Space Observatory (ISO). Three fields were also measured using the ISOCAM circular variable filter (CVF). The CVF data show that the 5-16.6 µm spectrum is dominated by the pure (v=0-0) ro…
The Lutz-Kelker bias in trigonometric parallaxes
Groenewegen, Martin A. T.; Schrijver, Hans; Oudmaijer, Rene D.
The theoretical prediction that trigonometric parallaxes suffer from a statistical effect has become topical again now that the results of the Hipparcos satellite have become available. This statistical effect, the so-called Lutz-Kelker bias, causes observed parallaxes to be too large. This has the implication that inferred distances, and hence in…
The birth of a planetary nebula around the carbon star IRC+10216
Meixner, M.; Skinner, C. J.; Bobrowsky, M.
Our current understanding of the evolution of solar-type stars suggests that after a period as a red giant star, during which mass loss occurs continuously in the form of a stellar wind, a period of intense mass loss known as a superwind occurs, during which a significant fraction of the envelope of the star is ejected into space, forming the mate…
A Three-mode, Variable Velocity Jet Model for HH 34
Noriega-Crespo, A.; Raga, A.
Variable ejection velocity jet models can qualitatively explain the appearance of successive working surfaces in Herbig-Haro (HH) jets. This paper presents an attempt to explore which features of the HH 34 jet can indeed be reproduced by such a model. From previously published data on this object, we find evidence for the existence of a three-mode…
Infrared Observations of Ongoing Star Formation in the 30 Doradus Nebula and a Comparison with Hubble Space Telescope WFPC 2 Images
Walborn, Nolan R.; Barbá, Rodolfo H.; Rubio, Mónica +3 more
Intercomparisons of ground-based IR continuum and H_2 images with Hubble Space Telescope WFPC2 images of the 30 Dor Nebula reveal detailed structural relationships, which provide new information about current star formation there. Numerous stellar IR sources have been discovered in or near the bright nebular filaments west and northeast of R136; t…
Optical and Near-Infrared Model Images of the Circumstellar Environments of Classical T Tauri Stars
Wood, Kenneth; Kenyon, Scott J.; Whitney, Barbara +1 more
We describe model calculations of optical and near-infrared scattered light images expected from class II T Tauri stars--the star-plus-disk systems. The parameters controlling the disk shape, size, and mass are chosen to be within theoretically and observationally derived limits. We restrict our models to nearly edge-on disks, since for lower incl…
Ulysses' rapid crossing of the polar coronal hole boundary
Forsyth, R.; Balogh, A.; McComas, D. J. +2 more
The Ulysses spacecraft crossed from the slow dense solar wind characteristic of the solar streamer belt into the fast, less dense flow from the northern polar coronal hole over a very short interval (several days) in late March 1995. The spacecraft, which was at 1.35 AU and ~19° north heliographic latitude, moving northward in its orbit, remained …