S. Towers

Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Manuel Bautista

Second Advisor

Dr. Kirk Korista

Third Advisor

Dr. Elena Litvinova


Eta Carinae, massive stars, stellar explosions, [Fell] Spectra, HST spectra

Access Setting

Masters Thesis-Open Access


Eta Carinae is an unparalleled object crossing many divisions of astrophysics. It has multiple, complicated and dynamic processes leading to absorption and emission spectra across all wavelengths from radio to hard x-ray. The spectra differ spatially across Eta Carinae's extended envelope and are changing rapidly over time.

The Weigelt Knots of Eta Carinae's ejecta emit spectra of numerous forbidden iron species lines, rare on Earth, but prevalent in the unique conditions surrounding this star. The Weigelt Knots' unique conditions occur almost nowhere else, making Eta Carinae, useful not only for understanding massive stars similar to it, but for understanding the inner workings of atoms.

This object has been observed with the Hubble Space Telescope extensively from 1998 to 2004 and the data still needs to be analyzed in more depth to finally shed light onto Eta Carinae's puzzling nature. Eta Carinae is very difficult to understand because of its uniqueness and complexity, so every avenue of study should be exercised.

I have systematically measured the fluxes of over 100 forbidden Fe II spectral lines in each of the six epochs of Eta Carinae's 5.54 year spectral cycle. These data are used as a probe to better understand the physical process of the star's variability and as a test against current theoretical Fe II spectral models. There is a lack of consensus in current theoretical iron models, which can only be solved by comparing theory to observation using measurements such as these.

Eta Carinae has arrested the interest of astronomers for centuries and still leaves many unanswered questions. There is much to resolve about Eta Carinae, its probable binary nature, its periodicity, and the reasons for its various outbursts. The nature and fate of the most massive stars in general is still poorly understood. Through this research I hope to play my small part in resolving Eta Carinae's mysteries.