Adair Sam midp site pic

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

High School: 

Institution when accepted: University of Hawaii at Hilo

Akamai Project: Determining the Distance to the M33 Galaxy Using Cepheid Variable Stars

Project Site: Big Island, Waimea 

Mentor: Chien-Hsiu Lee


Project Abstract:

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.