Sam (Samuel) was born in Kanagawa prefecture in Japan but was raised in White Bear Lake, Minnesota. Currently pursuing a bachelor’s degree in astronomy at University of Hawaii at Hilo. After completing his bachelor’s, he may pursue a doctorate. In his free time he likes to watch movies or play spike ball with his friends.
Home Island: Hawaii Island
Institution when accepted: University of Hawaii at Hilo
Akamai Project: Determining the Distance to the M33 Galaxy Using Cepheid Variable Stars
Cepheids are pulsating variable stars that periodically increase and decrease in luminosity as their diameter regularly grows and shrinks over the span of a few days. The strong relationship between a Cepheid’s pulsation period and its luminosity is well known, and it can therefore be used as a distance indicator. If a neighboring galaxy has enough known Cepheids, an estimated distance to that galaxy can be found by using the Cepheid period-luminosity relation. For this project, I analyzed archival data of M33 (the Triangulum Galaxy) taken by Hartman et al. using MegaCam at the Canada-France-Hawaii Telescope, in g, r, and i-band filters. To determine the distance to M33, I created Python code that performed several analytical steps: first, the code read in light curves of variable sources from the archival data and used the Lomb-Scargle algorithm to find a period in each filter. Using these periods, I plotted phased light curves and manually identified 1989 variable stars. Since Cepheids occupy a specific region called the instability strip on the H-R diagram, I used that to differentiate Cepheids from other variables. This identified a sample of 1622 Cepheids, the largest Cepheid sample from M33 to date. I further classified these Cepheids into different sub-classes, then used fundamental-mode Cepheids to estimate the distance for M33 to be 898.26 kpc. This result is in agreement with past results from different methods.