2019 Summer Undergraduate Research Program (SURP)

Presentation Type

Open Access Poster Presentation

Keywords

Cepheids; Fourier analysis;

Abstract

Cepheid stars are valuable due to their usefulness in determining distances within our galaxy, and to other galaxies. Cepheid stars’ light variation can be parameterized using a Fourier series with coefficients Ai and 𝜙i . Fourier coefficients have been shown to have trends linked to physical characteristics of Cepheids and RR Lyrae stars, such as luminosity, radius, pulsation modes and metallicity. Using data from the OGLE III and IV surveys, we determined relationships between Fourier coefficients in different photometric system and observed the influence of metallicity on the Cepheids in the Small Magellanic Cloud and the Large Magellanic Cloud. The results obtained for each galaxy will be compared with each other and with data from prior studies to provide a more complete overall picture of trends observed in the Fourier coefficients for Cepheids.

Start Date

2-8-2019 11:30 AM

End Date

2-8-2019 1:30 PM

Event Host

Summer Undergraduate Research Program, University of Northern Iowa

Faculty Advisor

Siobahn Morgan

Department

Department of Earth and Environmental Sciences

File Format

application/pdf

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Aug 2nd, 11:30 AM Aug 2nd, 1:30 PM

Investigating Fourier Coefficient Relationships of Cepheid Variable Stars

Cepheid stars are valuable due to their usefulness in determining distances within our galaxy, and to other galaxies. Cepheid stars’ light variation can be parameterized using a Fourier series with coefficients Ai and 𝜙i . Fourier coefficients have been shown to have trends linked to physical characteristics of Cepheids and RR Lyrae stars, such as luminosity, radius, pulsation modes and metallicity. Using data from the OGLE III and IV surveys, we determined relationships between Fourier coefficients in different photometric system and observed the influence of metallicity on the Cepheids in the Small Magellanic Cloud and the Large Magellanic Cloud. The results obtained for each galaxy will be compared with each other and with data from prior studies to provide a more complete overall picture of trends observed in the Fourier coefficients for Cepheids.