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Photochemistry of Saturn's Atmosphere. II. Effects of an Influx of External Oxygen
Bézard, Bruno; Lellouch, Emmanuel; Moses, Julianne I. +3 more
We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry. In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts…
ISO-SWS spectroscopy of gas-phase C_2H_2 and HCN toward massive young stellar objects
van Dishoeck, E. F.; Lahuis, F.
Observations of gas-phase C_2H_2 and HCN along the line of sight toward a large sample of deeply embedded massive young stellar objects (YSOs) have been performed using the Short Wavelength Spectrometer on board the Infrared Space Observatory. The nu_5 vibration-rotation band of C_2H_2 around 13.7 µm and the nu_2 band of HCN around 14.0 &mic…
Hubble Space Telescope Observations of Oxygen-rich Supernova Remnants in the Magellanic Clouds. II. Elemental Abundances in N132D and 1E 0102.2-7219
Blair, William P.; Kirshner, Robert P.; Hughes, John P. +6 more
We present Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 images and Faint Object Spectrograph data of two young supernova remnants in the Magellanic Clouds, N132D (LMC) and 1E 0102.2-7219 (SMC). The spectra cover essentially the entire UV/optical range available to HST and provide the first true comparison of UV/optical line inten…
The η Chamaeleontis Cluster: Origin in the Sco-Cen OB Association
Feigelson, Eric D.; Mamajek, Eric E.; Lawson, Warrick A.
A young, nearby compact aggregate of X-ray-emitting pre-main-sequence stars was recently discovered in the vicinity of η Chamaeleontis. In this paper, we further investigate this cluster: its membership, its environs, and its origins. ROSAT High Resolution Imager X-ray data for the cluster's T Tauri stars show high levels of magnetic activity and …
Testing the connection between the X-ray and submillimetre source populations using Chandra
Kneib, J. -P.; Ivison, R. J.; Smail, Ian +8 more
The powerful combination of the Chandra X-ray telescope, the SCUBA submillimetre-wave camera and the gravitational lensing effect of the massive galaxy clusters A2390 and A1835 has been used to place stringent X-ray flux limits on six faint submillimetre SCUBA sources and deep submillimetre limits on three Chandra sources which lie in fields commo…
An IUE Atlas of Pre-Main-Sequence Stars. I. Co-added Final Archive Spectra from the SWP Camera
Valenti, Jeff A.; Johns-Krull, Christopher M.; Linsky, Jeffrey L.
We have identified 50 T Tauri stars (TTS) and 74 Herbig Ae/Be (HAEBE) stars observed in the IUE short-wavelength bandpass (1150-1980 Å). Each low-resolution (R~6 Å) spectrum was visually inspected for source contamination and data quality, and then all good spectra were combined to form a single time-averaged spectrum for each star. Use of IUE Fin…
Simultaneous SOHO and Ground-Based Observations of a Large Eruptive Prominence and Coronal Mass Ejection
Heinzel, P.; Plunkett, S. P.; Wu, S. T. +6 more
Coronal mass ejections (CMEs) are frequently associated with erupting prominences near the solar surface. A spectacular eruption of the southern polar crown prominence was observed on 2June 1998, accompanied by a CME that was well-observed by the LASCO coronagraphs on SOHO. The prominence was observed in its quiescent state and was followed throug…
Detection of coronal mass ejection associated shock waves in the outer corona
Sheeley, N. R.; Hakala, W. N.; Wang, Y. -M.
White light coronal images from the Large-Angle Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SOHO) spacecraft show disturbances propagating away from high-speed coronal mass ejections (CMEs). The disturbances are faintly visible ahead of the ejected material at the noses of the CMEs but are strongly visible along th…
Quantitative analysis of WC stars: constraints on neon abundances from ISO-SWS spectroscopy
Hillier, D. John; Morris, Patrick W.; Crowther, Paul A. +3 more
Neon abundances are derived in four Galactic WC stars - γ2Vel (WR11, WC8+O7.5III), HD156385 (WR90, WC7), HD192103 (WR135, WC8) and WR146 (WC5+O8) - using mid-infrared fine-structure lines obtained with ISO-SWS. Stellar parameters for each star are derived using the non-local thermodynamic equilibrium model atmospheric code of Hillier &a…
The Hubble Deep Field South: Formulation of the Observing Campaign
Ferguson, Henry C.; Lucas, Ray A.; Brown, Thomas M. +51 more
Deep, multiband observations of high Galactic latitude fields are an essential tool for studying topics ranging from Galactic structure to extragalactic background radiation. The Hubble Deep Field (HDF-N) observations obtained in 1995 December established a standard for such narrow, deep surveys. The field has been extensively analyzed by a variet…