Physical Sciences and Mathematics Commons^™

Molecular Gas In The Circumstellar Environment Of Unusual Evolved Stars, Sarah E. Malek

Electronic Thesis and Dissertation Repository

As low- and intermediate mass stars (with masses up to 8-9 solar masses) age, they experience a series of evolutionary changes which culminate in the removal of nearly their entire envelope through extensive mass loss. The ejected material cools down, which allows for the formation of molecules and the nucleation of dust grains in the circumstellar environment (CSE) of the star. Much about the properties and composition of the gas and dust in these CSEs is not well understood.

Here, we study the rich CSEs of two unusual evolved stars by analyzing spectral observations in the infrared and using molecular …

A Variability Study Of The Typical Red Supergiant Antares A, Teznie J D Pugh

Electronic Thesis and Dissertation Repository

Red giants and red supergiants have long been known to be variable. In the last 40 years many of the features of this variability have been associated with large convective cells. Unfortunately, due to the long timescales of these variations they are not well studied, with the exception of the bright M-class supergiant Betelgeuse (α Orionis, M2 Iab). Betelgeuse has been well studied both observationally and theoretically, and has many features that are well described by models of convection. It was these studies of Betelgeuse that provided the main motivation for this thesis. We ask if the dramatic motions seen …

A Multispectral Assessment Of Complex Impact Craters On The Lunar Farside, Bhairavi Shankar

Electronic Thesis and Dissertation Repository

Hypervelocity collisions of asteroids onto planetary bodies have catastrophic effects on the target rocks through the process of shock metamorphism. The resulting features, impact craters, are circular depressions with a sharp rim surrounded by an ejecta blanket of variably shocked rocks. With increasing impact energy, the inner crater cavity can preserve complex morphologies including terraced walls, central uplifts, and melted rocks. The lack of erosion due to the absence of water or an atmosphere makes the Moon the perfect target to study impact crater processes, in particular the distribution of highly shocked materials within impact craters of different sizes. …