A search for low mass companions and a new determination of effective temperatures for T-Tauri stars

Simple item page
dc.contributor.advisorHartigan, Patrick M.en_US
dc.creatorHuerta, Marcosen_US
dc.date.accessioned2009-06-03T21:13:31Zen_US
dc.date.available2009-06-03T21:13:31Zen_US
dc.date.issued2007en_US
dc.description.abstractI present an analysis of over 300 spectra of the photospheres of young stars in order to address three outstanding questions of current interest: (1) whether or not the youngest stars are accompanied by massive substellar companions, (2) the degree to which starspots influence radial velocity measurements in young stars, and (3) establishment of a scale to convert spectral observations to effective temperatures and determining effective temperature for a large sample of stars. The first question is essential for understanding the star and planet formation process, the second question sets fundamental limits on ability of radial velocity surveys to detect young planets, and the third is a key for getting accurate mass and age estimates. Results from a new radial velocity survey of T Tauri stars focus on three specific stars---BP Tau, DN Tau, and LkCa19---with the largest number of observations. All the objects show far greater radial velocity variability than our radial velocity standards. Using a new simulation of the effect of star spots on the photometric and radial velocity variability of T Tauri star, I show the data for LkCa19 is fully consistent with variations caused by large star spots present on this rapidly rotating young star. In the case of BP Tau and DN Tau, the origin of the velocity variability is currently not well established. I also present the results of a new method to determine the effective temperature for weak-lined T Tauri stars, from the direct fitting of TiO bands near 7000 to NextGen synthetic spectra. The new temperatures are consistently warmer (by as much as 400K) than previous determinations based on spectral type. For the lowest mass young stars, the revised effective temperature doubles the mass inferred from evolutionary models.en_US
dc.format.extent116 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS PHYS. 2007 HUERTAen_US
dc.identifier.citationHuerta, Marcos. "A search for low mass companions and a new determination of effective temperatures for T-Tauri stars." (2007) Diss., Rice University. <a href="https://hdl.handle.net/1911/20684">https://hdl.handle.net/1911/20684</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/20684en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectAstronomyen_US
dc.subjectAstrophysicsen_US
dc.titleA search for low mass companions and a new determination of effective temperatures for T-Tauri starsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentPhysicsen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
3257335.PDF
Size:
4.67 MB
Format:
Adobe Portable Document Format
Download
Collections
Rice University Theses and Dissertations