Physics & Astronomy ETDs

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The problem of determining the periods of objects oscillating in one or more modes is discussed. Although the methods described are applicable to many different kinds of objects and observations, the discussion has been limited to double mode Cepheid stars.

Two methods of solution are followed in detail. An autocorrela­tion technique based on the scatter of points in an amplitude-phase plane is used for most cases. A means of calculating smoothed mean curves is discussed. A Fourier transform method is presented for closely spaced data points, with prewhitening included for accurate secondary period and amplitude determinations.

Three test problems are used to verify the feasibility of the methods. In most cases, the results agree with input data with less than one percent error.

Data from four of the eight known double mode Cepheid stars are used to cross-check previous period determinations. Oscillation amp­litudes previously unavailable for two of the stars are obtained. Results indicate that these four stars have similar secondary to primary period ratios near 0.70.

A description of the computer program used and requirements for its useage are given.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

David S. King

Second Committee Member

Howard Carnes Bryant

Third Committee Member

Christopher Pratt Leavitt

Document Type