On parabolic orbits of double stars with application to 7,1639 (ADS 8539)

There are certain visual double stars which, when close to a node of their relative orbit, should have enough radial velocity difference (10-20 km/s) that the spectra of the two component stars will appear resolved on high-dispersion spectrograms (5 Å/mm or less) obtainable by use of modern coudé and solar spectrographs on bright stars. Both star images are then recorded simultaneously on the spectrograph slit, so that two stellar components will appear on each spectrogram.

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Discovery and Measurement of Double Stars by Lunar Occultations

International Astronomical Union Colloquium ◽

10.1017/s0252921100027445 ◽

1965 ◽

Vol 5 ◽

pp. 28-37

Author(s):

R. Edward Nather ◽

David S. Evans

Keyword(s):

The Moon ◽

Double Stars ◽

Stellar Diameters ◽

Diffraction Effects

When a star is occulted by the dark limb of the Moon its apparent intensity drops to zero very quickly. MacMahon (1909) proposed that the time of disappearance would measure the diameter of the star, but Eddington (1909) demonstrated that diffraction effects at the lunar limb would lengthen the apparent time of disappearance to about 20 msec, and suggested that these effects would greatly limit the usefulness of the technique. MacMahon’s paper indicates that he was aware that stellar duplicity could be detected from occultation observations, but he did not amplify the point and Eddington did not comment on it. While it has been demonstrated theoretically by Williams (1939) and experimentally by Whitford (1939) and others that stellar diameters of a few arcmsec can be measured by this technique, its use for the discovery and measurement of double stars has been only incidental to other programs (O’Keefe and Anderson, 1952; Evanset al., 1954). Properly exploited, the method can contribute materially to the study of double stars.

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DESTINY: Database for the Effects of STellar encounters on dIsks and plaNetary sYstems

Computational Astrophysics and Cosmology ◽

10.1186/s40668-019-0030-3 ◽

2019 ◽

Vol 6 (1) ◽

Cited By ~ 2

Author(s):

Asmita Bhandare ◽

Susanne Pfalzner

Keyword(s):

Planetary System ◽

Planetary Systems ◽

Gravitational Effect ◽

Parameter Study ◽

Orbital Inclination ◽

Particle Properties ◽

Disk Size ◽

Stellar Group ◽

Cluster Environment ◽

Parabolic Orbits

Abstract Most stars form as part of a stellar group. These young stars are mostly surrounded by a disk from which potentially a planetary system might form. Both, the disk and later on the planetary system, may be affected by the cluster environment due to close fly-bys. The here presented database can be used to determine the gravitational effect of such fly-bys on non-viscous disks and planetary systems. The database contains data for fly-by scenarios spanning mass ratios between the perturber and host star from 0.3 to 50.0, periastron distances from 30 au to 1000 au, orbital inclination from 0∘ to 180∘ and angle of periastron of 0∘, 45∘ and 90∘. Thus covering a wide parameter space relevant for fly-bys in stellar clusters. The data can either be downloaded to perform one’s own diagnostics like for e.g. determining disk size, disk mass, etc. after specific encounters, obtain parameter dependencies or the different particle properties can be visualized interactively. Currently the database is restricted to fly-bys on parabolic orbits, but it will be extended to hyperbolic orbits in the future. All of the data from this extensive parameter study is now publicly available as DESTINY.

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SUSI’s Potential for Double Star Research

International Astronomical Union Colloquium ◽

10.1017/s0252921100007041 ◽

1992 ◽

Vol 135 ◽

pp. 521-526

Author(s):

John Davis

Keyword(s):

Angular Resolution ◽

Double Star ◽

Double Stars ◽

Stellar Interferometer ◽

New Instrument

AbstractThe Sydney University Stellar Interferometer (SUSI) is currently undergoing commissioning and will soon commence its astronomical program in which observations of double stars will form a major component. With its 640-m long North–South array of input siderostats, the new instrument will have unprecedented angular resolution.

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