Science Archives Publication System

Hubble Space Telescope/Faint Object Spectrograph Imaging of Wolf 424 AB: Is This Binary a Double Brown Dwarf System?

DOI: 10.1086/316115 Bibcode: 1998PASP..110...31S

Benedict, G. F.; Franz, O. G.; Bruhweiler, F. C. +9 more

The low-mass binary system Wolf 424 AB (GJ 473 AB) was spatially resolved in an image obtained on 1996 April 16 with the imaging mode of the Hubble Space Telescope Faint Object Spectrograph. The separation was measured to be 0.42"+/-0.03" at a position angle of 353.2d+/-2.5d. The new measurement was combined with previously published orbital posit…

1998 • Publications of the Astronomical Society of the Pacific

eHST 8

Search for H2 Emission from Disks around T Tauri and Herbig AE Stars

DOI: 10.1023/A:1001110801449 Bibcode: 1998Ap&SS.255...77V

Thi, W. F.; van Dishoeck, E. F.; Blake, G. A. +4 more

Preliminary results are presented of observations of the pure rotational lines of H2 toward T Tauri and Herbig Ae stars using the Short Wavelength Spectrometer (SWS) on the Infrared Space Observatory (ISO). The sources are selected to be isolated low- and intermediate-mass young stellar objects, for which the presence of a circumstellar disk has b…

1998 • Astrophysics and Space Science

ISO 8

SBF distances to Leo and Virgo using the HST

DOI: 10.1046/j.1365-8711.1998.01623.x Bibcode: 1998MNRAS.298..451M

Morris, P. W.; Shanks, T.

We use archive HST WFPC2 data for three elliptical galaxies (NGC 3379 in the Leo I group, and NGC 4472 and 4406 in the Virgo cluster) to determine their distances using the surface brightness fluctuation (SBF) method as described by Tonry & Schneider. A comparison of the HST results with the SBF distance moduli found by Ciardullo et al. shows …

1998 • Monthly Notices of the Royal Astronomical Society

eHST 8

Long-duration high-energy proton events observed by GOES in October 1989

DOI: 10.1007/s00585-998-0921-0 Bibcode: 1998AnGeo..16..921A

Vainio, R.; Torsti, J.; Anttila, A. +1 more

We consider the prolonged injection of the high-energy (>10 MeV) protons during the three successive events observed by GOES in October 1989. We apply a solar-rotation-stereoscopy approach to study the injection of the accelerated particles from the CME-driven interplanetary shock waves in order to find out how the effectiveness of the particle…

1998 • Annales Geophysicae

SOHO 8

Pulsating and nonpulsating stars in Hyades observed by HIPPARCOS satellite

Bibcode: 1998A&A...331..995A

Antonello, E.; Pasinetti Fracassini, L. E.

A study of the stars in the instability strip of Hyades cluster has been performed taking into account the new estimate of the stellar parallaxes. For taking advantage of the improved accuracy of the distances and hence absolute magnitudes it is necessary to separate the photometric effects of close companions, which appear quite common in Hyades.…

1998 • Astronomy and Astrophysics

Hipparcos 8

The He⁺/H⁺ Abundance in the Orion Nebula from Infrared Space Observatory Measurements

DOI: 10.1086/311470 Bibcode: 1998ApJ...501L.209R

Dufour, Reginald J.; Rubin, Robert H.; Colgan, Sean W. J. +1 more

Using the Short Wavelength Spectrometer on the Infrared Space Observatory, we measured in the Orion Nebula several components of the He I Brα transition, the first detections to the best of our knowledge in an H II region, and the H I Brα line. A value of He⁺/H⁺=0.085+/-0.003 is inferred from these data and is typical of prev…

1998 • The Astrophysical Journal

ISO 8

Properties of the Young Stellar Object N 160 A-IR

Bibcode: 1998A&A...338L..51H

Siebenmorgen, R.; Stecklum, B.; Fitzpatrick, E. L. +3 more

We present near- and mid-infrared images of the young stellar object N 160 A-IR in the Large Magellanic Cloud (LMC). For the first time, the YSO is seen in the NIR as a compact point source in the north-western part of the H ii region N 160 A. Furthermore, we present ISO-SWS spectra pointed on the YSO. The spectra cover the full wavelength range o…

1998 • Astronomy and Astrophysics

ISO 8

Hipparcos data for two open clusters containing cepheids

DOI: 10.1016/S1384-1076(97)00048-1 Bibcode: 1998NewA....3..121L

Lindegren, L.; Lyngå, G.

Using proper motion data from the Hipparcos satellite it is shown that the cepheids S Nor and U Sgr are members of the open clusters NGC 6087 and M 25, respectively. The precision of the Hipparcos data is needed to conclusively carry out a membership test. Parallax data, also obtained from Hipparcos, do not contradict the proper motion results.

1998 • New Astronomy

Hipparcos 8

ISOCAM Imaging of LBVS

DOI: 10.1023/A:1001182228708 Bibcode: 1998Ap&SS.255..195T

Waters, L. B. F. M.; Trams, N. R.; Voors, R. H. M.

1998 • Astrophysics and Space Science

ISO 8

Low-dimensional dynamics outside the laboratory: The case of roAp stars

DOI: 10.1209/epl/i1998-00548-y Bibcode: 1998EL.....42...31M

Boyd, P. T.; Mindlin, G. B.; Merener, N.

In this work, we build a nonlinear model to account for the time variable energy flux of a class of pulsating stars which is simple and robust, and test it against recent observations made with the Hubble Space Telescope. By the construction of a standard global normal form for the model, we not only check that the model has solutions qualitativel…

1998 • EPL (Europhysics Letters)

eHST 8