Spectroscopic detection and characterization of extreme flux-ratio binary systems

dc.contributor.advisorKraus, Adam L.en
dc.contributor.committeeMemberJaffe, Daniel Ten
dc.contributor.committeeMemberDodson-Robinson, Sarahen
dc.contributor.committeeMemberRobinson, Edward Len
dc.contributor.committeeMemberMeyer, Michaelen
dc.creatorGullikson, Kevin Carlen
dc.creator.orcid0000-0002-9056-2052en
dc.date.accessioned2016-08-16T16:23:46Z
dc.date.available2016-08-16T16:23:46Z
dc.date.issued2016-05
dc.date.submittedMay 2016
dc.date.updated2016-08-16T16:23:46Z
dc.description.abstractBinary stars and higher-order multiple systems are a ubiquitous outcome of star formation, especially as the system mass increases. The companion mass-ratio distribution is a unique probe into the conditions of the collapsing cloud core and circumstellar disk(s) of the binary fragments. Inside a ~1000 AU the disks from the two forming stars can interact, and additionally companions can form directly through disk fragmentation. We might therefore expect the mass-ratio distribution of close companions to differ from that of wide companions. This prediction is difficult to test with intermediate-mass primary stars using traditional methods because the contrast ratios that would be required to detect low-mass companions at narrow working angles are not yet achievable. In this thesis, we present a spectroscopic method to detect and characterize close companions to a variety of stars. We demonstrate applications of the method to detection of stars and even planets around sun-like stars, and present the results of a survey searching for companions to A- and B-type stars. As part of the survey, we estimate the temperatures and surface gravity of most of the 341 sample stars, and derive their masses and ages. We additionally estimate the temperatures and masses of the 64 companions we find, 23 of which are new detections. We find that the mass-ratio distribution for our sample has a turnover near q ~0.3, in contrast to the scale-free power law that describes the widely separated binary systems. We take this characteristic scale as evidence that companions are accreting a significant of material through disk interactions as they form, and that the scale is largely set by the disk lifetime and the time at which the fragments form.en
dc.description.departmentAstronomyen
dc.format.mimetypeapplication/pdfen
dc.identifierdoi:10.15781/T2QJ77Z44en
dc.identifier.urihttp://hdl.handle.net/2152/39460en
dc.language.isoenen
dc.subjectBinary starsen
dc.subjectStar formationen
dc.titleSpectroscopic detection and characterization of extreme flux-ratio binary systemsen
dc.typeThesisen
dc.type.materialtexten
thesis.degree.departmentAstronomyen
thesis.degree.disciplineAstronomyen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen
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