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Halo stars, starbursts, and distant globular clusters: A survey of unresolved objects in the Hubble Deep Field
Elson, Rebecca A. W.; Gilmore, Gerard F.; Santiago, Basilio X.
We present a survey of unresolved objects in the Hubble Deep Field. We find 59 such objects with I814≤ 28. Only nine are candidates for low mass ( m ≤ 0.5M ⊙) halo stars. This rules out a steeply rising luminosity function fainter than M v = 12, and precludes low mass stars as a major constituent of halo dark matte…
The Gaseous Sulfur Dioxide Abundance over Io's Leading and Trailing Hemispheres: HST Spectra of Io's C 1B 2--X 1A 1 Band of SO 2 near 2100 Angstrom
Trafton, L. M.; Caldwell, J. J.; Barnet, C. +1 more
We report ultraviolet HST/GHRS observations of Io's spectrum at opposite orbital elongations in the wavelength band 2095-2135 Å smoothed to an effective resolution of 3.7-4.1 Å. Gaseous SO2 absorption over Io's trailing sunlit hemisphere was found to be 37% stronger than over the leading sunlight hemisphere. The effective two-way path o…
Latitudinal dependence of the radial IMF component - interplanetary imprint.
Phillips, J.; Smith, E. J.; Goldstein, B. E. +2 more
Ulysses measurements have confirmed that there is no significant gradient with respect to heliomagnetic latitude in the radial component, B_r_, of the interplanetary magnetic field. There are two processes responsible for this observation. In the corona, the plasma β is <<1, except directly above streamers, so both longitudinal and latitudin…
The ISO-SWS spectra of Luminous Blue Variables.
Heras, A. M.; Waters, L. B. F. M.; Kudritzki, R. P. +7 more
We present the infrared spectra between 2.4 and 45µm of two Luminous Blue Variables (AG Car, HR Car) observed with the Short Wavelength Spectrometer of ISO. The spectra consist of two parts: (1) the tail of the photospheric energy distribution with the free-free excess from the lower layers of the stellar wind, (2) emission from circumstella…
The starburst galaxy NGC 6090: from 2.5µm to 200µm.
Schulz, B.; Laureijs, R. J.; Abraham, P. +10 more
We have carried out broad band photometry of the interacting galaxy system NGC 6090 from 3.6 to 200µm using ISOPHOT. This is complemented by a low resolution spectrum in the wavelength range 2.5-11.5µm. The IR spectral energy distribution of a starburst galaxy is shown with unprecedented detail. From our Far Infrared measurements we ca…
Helical Strands in the Jetlike Narrow-Line Region of ESO 428-G14
Simpson, Chris; Bower, Gary A.; Wilson, Andrew S. +1 more
We present HST/WFPC2 images of the narrow-line region (NLR) of the Seyfert 2 galaxy ESO 428-G14 (0714-2914, M4-1). The NLR consists of many individual, thin strands, which are very closely related to the radio jet and produce a highly complex, yet ordered, structure. We find that the jet is two-sided, with a double helix of emission-line gas appar…
Fluorescent Hydroxyl Emissions from Saturn's Ring Atmosphere
Feldman, Paul D.; McGrath, Melissa A.; Holberg, J. B. +1 more
Just before Earth passed through Saturn's ring plane on 10 August 1995, the Hubble Space Telescope Faint Object Spectrograph detected ultraviolet fluorescent emissions from a tenuous atmosphere of OH molecules enveloping the rings. Brightnesses decrease with increasing distance above the rings, implying a scale height of about 0.45 Saturn radii (R…
Ulysses observations of whistler waves at interplanetary shocks and in the solar wind
Forsyth, R.; Balogh, A.; MacDowall, R. J. +4 more
This study of whistler wave emission observed by the Ulysses Unified Radio and Plasma Wave (URAP) experiment between 1 and 5 AU is a complement to previous studies of whistler waves observed by the Helios spacecraft between 0.3 and 1 AU. The Helios spacecraft continuously detected a background of whistlers close to the Sun, and this background was…
Multifrequency monitoring of RU Lupi. II. The model.
Rossi, C.; Giovannelli, F.; Vittone, A. A. +4 more
The data obtained during multifrequency monitoring of extreme T Tauri star RU Lupi and presented in Giovannelli et al. (1995), are explained by a model in which a young star with a moderately strong global magnetic field is actively accreting mass from a circumstellar disk. We argue that the magnetic field pressure stops the accretion disk at the …
The chemical compositions of three main-sequence B-type stars in the Large Magellanic Cloud.
Howarth, I. D.; Dufton, P. L.; Brown, P. J. F. +1 more
High-resolution observations of three B-type main-sequence stars in the Large Magellanic Cloud (LMC) have been obtained with the UCL echelle spectrograph on the 3.9-m Anglo-Australian Telescope. These spectra and IUE low-resolution spectroscopic data have been analysed using LTE model-atmosphere techniques, to derive stellar atmospheric parameters…