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GHRS Observations of Cool Low-Gravity Stars. III. Plasma Flows and Turbulence in the Outer Atmosphere of α Orionis (M2 Iab)

Robinson, Richard D.; Carpenter, Kenneth G.

We present the results of a Goddard High Resolution Spectrograph (GHRS) study of flow and turbulent velocities in the outer atmosphere of the M2 Iab supergiant α Ori. Ions with observed chromospheric emission features include C I, C II, Si I, Si II, O I, Co II, Al II, Mg II, Cr II, Fe I, and Fe II, while the photospheric absorption spectrum is dom…

Latitudinal Distribution of O ₂on Ganymede: Observations with the Hubble Space Telescope

Spencer, John R.; Calvin, Wendy M.

To help constrain the spatial variation of oxygen on Jupiter's satellite Ganymede, and hence have more clues to its mode of production and stability, we have obtained spectral data from the Faint Object Spectrograph (FOS) for a single pole-to-pole latitudinal strip, along with several Wide Field Planetary Camera 2 (WFPC2) images in three narrow ba…

Spectropolarimetry and nebular geometry of the symbiotic star HBV 475.

Schild, H.; Schmid, H. M.

We present and discuss spectropolarimetry of the Raman scattered emission features at λ6825 and λ7082 of the symbiotic nova HBV 475. Meaningful interpretation in relation to the orbital phase requires an improved ephemeris and we first review available photometry and deduce a new period of 956.5d and minimum epoch at JD 2444890. The flux of the λ6…

A New Luminous Blue Variable in the Giant Extragalactic H II Region NGC 2363

Drissen, Laurent; Robert, Carmelle; Roy, Jean-René

We report the discovery of an erupting luminous blue variable (LBV) star in the giant H II region NGC 2363, the most massive star-forming region in the Magellanic irregular galaxy NGC 2366. This LBV, presently the visually brightest star in the galaxy (M_V ~ -10.2), was first noticed in Hubble Space Telescope Wide Field Planetary Camera …

The O-Type Binary 15 Monocerotis Nears Periastron

Gies, Douglas R.; Penny, Laura R.; Bagnuolo, William G., Jr. +6 more

We present new radial velocity measurements for the massive binary 15 Monocerotis which indicate that the system is now very close to periastron (1996.9) in its 24 yr orbit. The velocity separation in the coming year may be large enough to permit an accurate estimate of mass ratio. We also present our first astrometric measurement of 15 Mon made w…

Eruptive prominence and associated CME observed with SUMER, CDS and LASCO (SOHO)

Schmieder, B.; Brekke, P.; Kucera, T. +3 more

Observations of an eruptive prominence were obtained on 1 May 1996, with the SUMER and CDS instruments aboard SOHO during the preparatory phase of the Joint Observing Programme JOP12. A coronal mass ejection observed with LASCO is associated temporally and spatially with this prominence. The main objective of JOP12 is to study the dynamics of prom…

Three massive binaries and the Struve-Sahade effect

Stickland, D. J.

The High Chromospheres of the Late A Stars

Simon, Theodore; Landsman, Wayne B.

We report the detection of N V 1239 Å transition region emission in HST/Goddard High Resolution Spectrograph spectra of the A7 V stars, α Aql and α Cep. Our observations provide the first direct evidence of 1-3 × 10⁵ K material in the atmospheres of normal A-type stars. For both stars, and for the mid A-type star τ³ Eri, we a…

Injection of large grains into orbits around comet nuclei.

Fulle, M.

Starting from the nucleus surface, the motion of dust boulders of diameters larger than the solar radiation pressure resonance size (Richter & Keller, 1995Icar..114..355R) is investigated by numerical integration of the motion equation for times larger than the comet orbital period. The motion equation takes into account the comet nucleus grav…

A test of Tully-Fisher distance estimates using Cepheids and SNIa

Shanks, T.

We make a direct test of Tully-Fisher distance estimates to 11 spiral galaxies with Hubble Space Telescope (HST) Cepheid distances, and to 12 spiral galaxies with Type Ia supernova (SNIa) distances. The HST Cepheid distances come from the work of Freedman, Sandage et al. and Tanvir et al. The SNIa distances come from Pierce, calibrated using the C…