Undergraduate Honors Theses

Thesis Defended

Spring 2016

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Astronomy

First Advisor

Dr. Kevin France

Second Advisor

Dr. Erica Ellingson

Third Advisor

Dr. Robert Marshall

Abstract

The Rosetta Alice (R-Alice) ultraviolet spectrograph on the European Space Agency Rosetta spacecraft, currently escorting the comet 67P/Churyumov-Gerasimenko in its orbit around the Sun, has observed the activity of the comet since encounter in August 2014. Fortuitous observations taken in October and November 2015, two and three months after perihelion respectively, show large increases in the Lyman-Beta, OI 1304, CII 1335, OI] 1356, and CI 1657 atomic emission lines that indicate gas outbursts. Due to the electron impact on gases in the cometary coma the data is compared to measured cross sections and line ratios to put constraints on outburst composition. Analysis of these emission lines and the ratios indicates that each primary outburst was driven by molecular oxygen and followed by a smaller secondary outburst. In both cases the secondary outburst contained a different composition of CO2 or H2O than in the primary outburst. These observations support the findings of Bieler et al. 2015 and detail the need for a formation mechanism that traps O2 in comets during formation.

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