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Дата изменения: Unknown Дата индексирования: Tue Apr 12 05:30:07 2016 Кодировка: Поисковые слова: annular |
FGS Instrument Handbook for Cycle 24 |
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It is possible to use the FGS in both Transfer and Position mode during a given observing session (visit). As was mentioned in Section 3.4, by using Transfer mode observations to determine a binary system’s true relative orbit, and using Position mode observations of nearby reference stars (and perhaps the binary as well) to determine the binary’s parallax, the system’s total mass can be derived. Furthermore, if the data are of sufficient quality, i.e., if the uncertainty in the position of each component with respect to the reference stars is small compared to the semi-major axis of the binary’s orbit, then the motion of each component about the system’s barycenter can be determined. From this information, the mass ratio, and hence the mass to luminosity ratio of each of the two stars, can be calculated.