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Carbon Stars

Knapp, Gillian R.; Wallerstein, George

Absolute magnitudes are estimated for carbon stars of various subtypes in the Hipparcos catalogue and as found in the Magellanic Clouds. Stellar radii fall within the limits of 2.4-4.7 AU. The chemical composition of carbon stars indicates that the C-N stars show nearly solar C/H, N/H, and ^12C/^13C ratios. This indicates that much of the C and N …

First Results from HIPPARCOS

Kovalevsky, J.

After recalling the principle of the Hipparcos mission and of the data reduction, the main statistical features of the final Hipparcos and Tycho catalogues are presented. The results, characterized by accuracies in annual proper motions and parallaxes of the order of one milliarcsecond have been already widely used for astrophysical investigations…

Eta Carinae and Its Environment

Humphreys, Roberta M.; Davidson, Kris

Eta Carinae (Eta) is one of the most remarkable of all well-studied stars and perhaps the most poorly understood. Observations with the Hubble Space Telescope and other modern instruments have solved a few of the mysteries concerning this object while opening a comparable number of new ones. In this review we first recount some essential backgroun…

Interstellar Abundances from Absorption-Line Observations with the Hubble Space Telescope

Sembach, Kenneth R.; Savage, Blair D.

The Goddard High-Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) has yielded precision abundance results for a range of interstellar environments, including gas in the local medium, in the warm neutral medium, in cold diffuse clouds, and in distant halo clouds. Through GHRS studies, investigators have determined the abundanc…

Corotating and Transient Solar Wind Flows in Three Dimensions

Gosling, J. T.

Two types of flows dominate the large-scale structure of the solar wind: corotating flows and transient disturbances. Corotating flows are associated with spatial variability in the coronal expansion and solar rotation, whereas transient disturbances are associated with episodic ejections of material into interplanetary space from coronal regions …

Massive Star Populations in Nearby Galaxies

Conti, Peter S.; Maeder, André

Astrophysical contributions of the International Ultraviolet Explorer.

Kondo, Yoji; Maran, Stephen P.; Boggess, Albert

The International Ultraviolet Explorer (IUE) was launched on Janurary 26, 1978. The mission was conceived from the beginning as an ultraviolet spectroscopic observatory that could be used by astronomers as they were accustomed to observing from the ground, without special training in orbital operations. The authors describe some highlights of the …

Herbig-haro objects.

Schwartz, R. D.

Progress in the understanding of Herbig-Haro (HH) objects is reviewed. The results of optical studies of the proper motions and alignments, variability, and polarization of HH objects and the results of spectroscopic studies are discussed. Ground-based infrared studies and far-infrared observations are reviewed. Findings on the properties of molec…