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The Remarkable Boron-depleted, Lithium-normal Population II Star HD 160617
Primas, F.; Duncan, D. K.; Thorburn, J. A.
We present results of an analysis of the boron spectral region (2500 Å) in the metal-poor star HD 160617, observed with the Goddard High Resolution Spectrograph of the Hubble Space Telescope. HD 160617 has a metallicity of [Fe/H]~-1.8, a Teff~5900 K, and a log g ~ 3.5. Its Li abundance is the normal, primordial ``Spite plateau'' value l…
HIPPARCOS absolute magnitudes for metal-rich K giants and the calibration of DDO photometry
Flynn, Chris; Hog, Erik
Parallaxes for 581 bright K giants have been determined using the Hipparcos satellite. We combine the trigonometric parallaxes with ground-based photometric data to determine the K giant absolute magnitudes. For all these giants, absolute magnitude estimates can also be made using the intermediate-band photometric David Dunlop Observatory (DDO) sy…
The Goddard High Resolution Spectrograph: Post-COSTAR Characteristics
Savage, B. D.; Ebbets, D. C.; Carpenter, K. G. +16 more
We review changes to the characteristics of the Goddard High Resolution Spectrograph (GHRS) which resulted from the installation of the Corrective Optics Space Telescope Axial Replacement (COSTAR) on the Hubble Space Telescope. The introduction of two new optical elements into the light path altered the spectral distribution of the light, decreasi…
Repetitive structure in the stellar wind of HD 93843: a normal O-type star
Howarth, Ian D.; Massa, Derck; Prinja, Raman K. +1 more
We present the results from a 28-day IUE time-series campaign monitoring the stellar wind of the O5-type giant HD 93843. The principal aim was to study variability in the wind of a star with a normal projected rotation velocity. Systematic changes are identified, amidst continuous line-profile variability, in the absorption troughs of the Siiv and…
Boron in the very metal-poor star BD -13 3442
Deliyannis, Constantine P.; Primas, F.; Rebull, L. M. +5 more
The Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) has been used to observe the boron 2500 Angstroms region of BD -13 3442. At a metallicity of [Fe/H]=-3.00 this is the most metal-poor star ever observed for B. Nearly 26 hours of exposure time resulted in a detection. Spectrum synthesis using the latest Kurucz mode…
ASCA observation of the polar RX J1802.1+1804
Greiner, J.; Motch, C.; Ishida, M. +1 more
We present X-ray data of {RX J1802.1+1804} obtained by {ASCA}. Although it shows a clear orbital intensity modulation with an amplitude of nearly 100% below 0.5 keV in {ROSAT} data, the {ASCA} light curves are nearly flat except for a possible dip lasting about one-tenth of the orbital period. We discuss this within the model assumption of a strea…
Particle acceleration efficiency and MHD characteristics of CIR-related shocks
Mann, G.; Keppler, E.; Classen, H. -T.
During its southbound journey the Ulysses spacecraft crossed a series of corotating interaction regions (CIRs) building up due to the interaction of fast and slow solar wind streams. We analyse the forward and the reverse shocks marking off the 18 CIR encounters between July 1992 and December 1993. Our investigations look for a correlation between…
SVS 16: The most X-ray luminous young stellar object
Stanke, Thomas; Preibisch, Thomas; Neuhaeuser, Ralph
We present new infrared and X-ray data on the optically invisible infrared source SVS 16 in the NGC 1333 star forming region. We show that SVS 16 is a binary with a separation of 1''. The infrared spectrum displays photospheric atomic and CO absorption lines, and thus shows that SVS 16 is a highly obscured (A_V ~ 26 mag) low mass young stellar obj…
Neutral hydrogen absorption observations of the central region of NGC 5929
Mundell, C. G.; Holloway, A. J.; Pedlar, A. +2 more
We present 0.15-arcsec (25-pc) resolution MERLIN observations of neutral hydrogen absorption detected towards the nuclear region of the type 2 Seyfert galaxy NGC 5929. Absorption is detected only towards the north-eastern radio component with a column density of (6.5+/-0.6)x10^21cm^-2. Based on comparison with an HST WFPC2 continuum image, we prop…
ISO Observations of Isolated Herbig AE/BE Stars
Waters, L. B. F. M.; Waelkens, C.; Malfait, K.
We report on SWS and LWS observations of the circumstellar disks of young stars of a few solar masses. The ISO spectra of these objects present a diversity of emission features of carbon-rich and oxygen-rich grains. The similarity of the forsterite spectra observed for Comet Hale-Bopp and the Haebe star HD100546 is particularly striking and provid…