305 research outputs found
The Orbit of the Binary Star Delta Scorpii
Although delta Scorpii is a bright and well-studied star, the details of its
multiplicity have remained unclear. Here we present the first
diffraction-limited image of this 0.12 arcsec binary star, made using optical
interferometry, and resolve the confusion that has existed in the literature
over its multiplicity.
Examining published speckle measurements, together with the present result,
reveals a periodicity of 10.5 yr and allows calculation of the orbital
parameters. The orbit has a high eccentricity (e=0.82) and large inclination
(i=70 degrees), making it a favourable target for radial velocity measurements
during the next periastron (in 2000).Comment: (LaTex 8 pages. Send email to '[email protected]' for 4 postscript
figures). To appear in the Astronomical Journal, August, 1993. ESO-TR
Scaled oscillation frequencies and echelle diagrams as a tool for comparative asteroseismology
We describe a method for comparing the frequency spectra of oscillating
stars. We focus on solar-like oscillations, in which mode frequencies generally
follow a regular pattern. On the basis that oscillation frequencies of similar
stars scale homologously, we show how to display two stars on a single echelle
diagram. The result can be used to infer the ratio of their mean densities very
precisely, without reference to theoretical models. In addition, data from the
star with the better signal-to-noise ratio can be used to confirm weaker modes
and reject sidelobes in data from the second star. Finally, we show that scaled
echelle diagrams provide a solution to the problem of ridge identification in
F-type stars, such as those observed by the CoRoT space mission.Comment: accepted for publication in Communications in Asteroseismolog
Observations of solar-like oscillations
There has been tremendous progress in observing oscillations in solar-type
stars. In a few short years we have moved from ambiguous detections to firm
measurements. We briefly review the recent results, most of which have come
from high-precision Doppler measurements. We also review briefly the results on
giant and supergiant stars and the prospects for the future.Comment: Invited review talk at the "Vienna Workshop on the Future of
Asteroseismology", 20-22 September 2006, to appear in Communications in
Asteroseismolog
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