Asteroseismic Study of the Subgiant HD 82074

This thesis analyzes HD 82074, a solar-mass and low-metallicity subgiant star, using ground-based asteroseismology with the CHIRON spectrometer at the Cerro Tololo Inter-American Observatory (CTIO) and interferometry with the CHARA array on Mt. Wilson. The physical parameters of subgiant stars are of particular interest in the exoplanetary field due to their importance in understanding the relationships between planet occurrence rate and stellar properties such as age, metallicity and mass. Potential systematic uncertainties in the canonical stellar models make it especially important to independently determine the masses and radii of these stars. We determine HD 82074's radius using interferometry from CHARA, and we combine this result with measurements of the spacing and frequencies of the asteroseismic oscillations of HD 82074 to determine a stellar mass. We find that the star has a radius of 3.96 0.12 solar radii and a mass of 1.20 0.11 solar masses. While the radius is in excellent agreement with predictions from spectral analysis, the mass is 2.9-o- greater than the predicted mass. This suggests that errors of stellar models may be underestimated for low-metollicity or evolved stars. This study makes HD 82074 the third subgiant for which a physical radius is confirmed interferometrically and one of ten asteroseismically studied subgiants.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2014

Author dc:creator

• Villar, Victoria Ashley

Advisor dc:contributor.advisor

• John A. Johnson and Joshua N. Winn.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/92674

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/92674