Search Publications

Relative intensities of intercombination lines in ultraviolet spectra of T Tauri stars

Lamzin, S. A.; Gomez de Castro, A. I.

Using the accretion shock wave model (Lamzin 1998), we calculate the relative intensities of the strongest intercombination lines in the range 1200-2000 Angstroms. We make a qualitative comparison of theoretical spectra with IUE low-resolution (~=6 Angstroms) spectra of T Tauri stars. We predict that several intercombination lines can be identifie…

An ISO view on interstellar dust heated by red giant stars

Epchtein, N.; Boulanger, F.; Lagache, G. +4 more

In order to study the structure and emission of the diffuse interstellar medium when it is heated by red giant stars, we have obtained ISOPHOT maps centered at proximity of a sample of such objects. The maps are 7'x7' with a pixel size of 45'', and were made at 60 and 90 mu m. Here we present the preliminary results of this program, based on data …

Two serendipitous low-mass LMC clusters discovered with HST1

Elson, Rebecca A. W.; Sigurdsson, Steinn; Gilmore, Gerard F. +1 more

We present V and I photometry of two open clusters in the LMC down to V~26. The clusters were imaged with the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope (HST), as part of the Medium Deep Survey Key Project. Both are low-luminosity (M_V~-3.5), low-mass (M~10^3 Msolar) systems. The chance discovery of these two clu…

Optimal Proper-Motion Measurements with the Wide Field and Planetary Camera

Lewis, Geraint F.; Ibata, Rodrigo A.

An optimal maximum-likelihood technique for computing point-source image centroids from many, slightly offset, CCD frames is presented. The method is especially useful for measuring stellar proper motions from data taken with the Wide Field and Planetary Camera on board the Hubble Space Telescope, and also provides a means to identify very compact…

CCD Positions for the Outer Planets in 1996-1997 Determined in the Extragalactic Reference Frame

Stone, Ronald C.

This paper presents 316 new equatorial positions for the planets Uranus, Neptune, and Pluto obtained in 1996-1997 with the Flagstaff Astrometric Scanning Transit Telescope (FASTT). All the positions were determined in the extragalactic reference frame using CCD observations and are accurate to ~+/-0.2" in each coordinate. When these positions are …

Hubble Space Telescope Resolved Image and Spectra of the Z ~= 2 QSO 1345+584

Hutchings, J. B.

QSO 1345+584 has been spatially resolved by direct images and in spectral images, and has asymmetrically extended flux to the west, where its inner radio structure is seen. The brightest knots in the resolved flux correspond closely with knots in the curved radio jet, and the brightest knot has a velocity of approach of some 3000 km s^-1 with resp…

The optical counterparts of γ-ray bursts

Harrison, Thomas E.; McNamara, Bernard J.

The origin of γ-ray bursts-which are among the most energetic events in the Universe-has puzzled astronomers for 25 years. Since 1991, new events have been discovered at a rate of about one per day, but because their positions were poorly determined, the objects responsible for these outbursts could not be identified. Now, following the launch of …

Spatial Interpolation for Four Spacecraft: Application to Magnetic Gradients

Harvey, Christopher C.; Chanteur, Gérard

Multi-Spacecraft Analysis of Plasma Kinetics

Schwartz, Steven J.; Daly, Patrick W.; Fazakerley, Andrew N.

HST Observation of GD 358

Kepler, S. O.; Winget, D. E.; Koester, D. +5 more

The success of asteroseismology lies in the correct identification of the star's normal modes of oscillation. Winget et al. (1994) identified the normal modes of a helium white dwarf pulsator, GD 358, through the frequency distribution of the pulsation. Robinson et al. (1995) described a new mode identification method by comparing the pulsation am…