Host galaxy morphology catalog

At a glance

My role

One of 10 undergraduate and graduate students on a team project at the University of Illinois. We all shared the work of writing the code and building the database.

What we did

Pulled a large sample of Type Ia supernovae from public databases, classified each host galaxy's shape, and looked for links between galaxy type and how the supernovae behaved.

What we compared

Intrinsic brightness, how fast each supernova faded, and metallicity (how rich in heavy elements it was).

Hubble image of NGC 5643, a face-on spiral galaxy with a bright core, two main spiral arms laced with dark dust lanes, and pink star-forming regions. — An example of a supernova host galaxy: the spiral galaxy NGC 5643, home of Type Ia supernova 2017cbv (after our project, so not in our sample). Image: ESA/Hubble (opens in a new tab) & NASA, A. Riess et al.; acknowledgement: Mahdi Zamani, CC BY 4.0 (opens in a new tab).

The question

Type Ia supernovae are used to measure distances across the universe, because they all reach about the same peak brightness. But "about the same" isn't exactly the same. We wanted to know whether the galaxy a supernova lives in helps explain the differences.

What we did

I looked at a large sample of Type Ia supernovae taken from the supernova database at the Harvard-Smithsonian Center for Astrophysics, the UC Berkeley Filippenko Group's Supernova Database, and other sources. We looked for correlations between host galaxy morphology and intrinsic brightness, decline rates, and metallicities.

The project involved cataloging 514 host galaxy morphologies, then using MySQL and Python to compare composite spectra, built by combining spectra from nearby supernovae measured at maximum brightness.