Search Publications

Moments of Plasma Velocity Distributions

Schwartz, Steven J.; Fazakerley, Andrew N.; Paschmann, Götz

ORFEUS Observations of Luminous Cool Stars

Dupree, A. K.; Brickhouse, N. S.

The ORFEUS telescope obtained far-ultraviolet spectra (λλ912-1218) of three luminous cool stars: β Draconis (HD 159181) and two hybrid stars, α Aquarii (HD 209750) and α Trianguli Australis (HD 150798). Most striking is the detection of blueshifted O VI λ1032, and C III λ977 emission relative to Si III λ1206, indicating outward motion, and the mar…

Photocentre displacement of minor planets: analysis of HIPPARCOS astrometry

Hestroffer, D.

We present a study of the phase effect (or photocentre offset) on the astrometry of minor planets. Analysis of the high precision Hipparcos observations of the largest asteroids shows the validity of the model. Minor planets Ceres, Pallas, Vesta and Iris show a brightness distribution close to the lunar scattering properties, while Juno and Hebe a…

Gamma-Ray Burst Counterparts: Optical Data

Schaefer, Bradley E.; Cline, Thomas L.; Hurley, Kevin C. +1 more

The surest solution of the gamma-ray burst (GRB) mystery is to find an unambiguous low-energy quiescent counterpart. To this end, we have intensively searched within the smallest GRB error boxes for any counterpart candidates. This paper reports on 255 hr of exposure with ground-based telescopes since 1981. We report our results in the U, B, V, R.…

Magnesium isotopic composition as observed with the CELIAS/MTOF experiment on the SOHO spacecraft

Livi, S.; Hsieh, K. C.; Wurz, P. +27 more

Solar wind abundance ratios of magnesium isotopes measured with the high resolution Mass Time-of-Flight spectrometer (MTOF) of the Charge, Element, and Isotope Analysis System (CELIAS) experiment on board the Solar and Heliospheric Observatory (SOHO) are presented. MTOF, as part of CELIAS, is, because of its high time and mass resolution, an excel…

Identification of lambda Bootis stars using IUE spectra. I. Low resolution data

Solano, E.; Paunzen, E.

An analysis of the stars included in the catalogue of lambda Bootis stars by Paunzen et al. (1997) and which also have IUE observations is presented here. Population I A-F type stars as well as field horizontal branch stars were also included in the analysis. Using line-ratios of carbon to heavier elements (Al and Ni) allows us to establish unambi…

The absolute magnitudes of Cepheids and the extragalacticdistance scale

Feast, Michael

It is pointed out that a Cepheid period-luminosity relation with a zero-point from Hipparcos trigonometrical parallaxes and a consistent reddening system zero-point implies that some recent estimates of H_0 based on the Cepheid scale should be increased by ~8 per cent. This result avoids using the distance to the Large Magellanic Cloud (LMC) as an…

Extreme Ultraviolet Explorer Investigation of Three Short-Period Binary Stars

Rucinski, Slavek M.

Extreme Ultraviolet Explorer spectroscopic observations (SW, MW, and LW bands, covering 80-160, 170-350, and 300-450 Å with resolutions 0.5, 1, and 2 Å, respectively) and photometric observations (Deep Sky Survey [DSS], broadband 70-140 Å) have been obtained for two contact binaries, 44i Boo B and VW Cep, and one close but detached binary, ER Vul.…

Progressive Star Bursts and High Velocities in the Infrared-luminous, Colliding Galaxy ARP 118

Gao, Yu; Lamb, Susan A.; Hearn, Nathan C.

In this Letter, we demonstrate for the first time the connection between the spatial and temporal progression of star formation and the changing locations of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the aftermath of its collision with a massive elliptical galaxy (NGC 1143). These two galaxies form the combined objec…

New Optical Fields and Candidates of 10 3C Radio Sources. I. The R-Band Images

Baum, Stefi A.; McCarthy, Patrick J.; Sparks, William B. +6 more

Using new R-band images acquired as part of the 3CR Snapshot Survey with the Wide Field Planetary Camera 2 on the Hubble Space Telescope, we present positive optical identifications of three previously unidentified 3C radio sources (3C 91, 134, and 141). The fields of five others (3C 131, 152, 399.1, 415.2, and 468.1) are also presented with tenta…