Optical fiber-fed spectroscopy of pulsating variable stars.
Poster Number
14
Format
Poster Presentation
Abstract/Artist Statement
Cepheid variable stars are giant stars with unstable outer atmospheres which pulsate radially with periods of days to weeks. As the surface of the star approaches and recedes from the observer, there is a measureable Doppler shift in the star's spectrum. This Doppler shift can be used to measure the rate of change of stellar radius in kilometers per second, which can be used to infer astrophysically interesting properties of the star, such as size and radius. In this poster, I describe a portable observational setup used to observe spectra of Cepheid variable stars. I used a 10-inch reflecting telescope, fiber-coupled to a small grating spectrograph, which imaged spectra with a CCD camera. The telescope and CCD were controlled by the same laptop computer. I designed and helped to construct a mirror fibercoupling for the telescope which allowed simultaneous guiding and spectroscopy. This component greatly improved the efficiency and reliability of the observations. I performed observations with this setup in an orchard in Salida from June 2002 to January 2003. I wrote a software package called "lambda" in the Interactive Data Language (IDL) which perfoms data processing and doppler shift measurements for the observations. I also performed similar measurements of the same data with the Image Reduction and Analysis Facility (IRAF) to double-check the results. In this poster I describe the results from the current observations with a particular emphasis on the radial velocity versus time and phase for the star Delta Cepheus.
Location
Pacific Geosciences Center
Start Date
26-4-2003 9:00 AM
End Date
26-4-2003 5:00 PM
Optical fiber-fed spectroscopy of pulsating variable stars.
Pacific Geosciences Center
Cepheid variable stars are giant stars with unstable outer atmospheres which pulsate radially with periods of days to weeks. As the surface of the star approaches and recedes from the observer, there is a measureable Doppler shift in the star's spectrum. This Doppler shift can be used to measure the rate of change of stellar radius in kilometers per second, which can be used to infer astrophysically interesting properties of the star, such as size and radius. In this poster, I describe a portable observational setup used to observe spectra of Cepheid variable stars. I used a 10-inch reflecting telescope, fiber-coupled to a small grating spectrograph, which imaged spectra with a CCD camera. The telescope and CCD were controlled by the same laptop computer. I designed and helped to construct a mirror fibercoupling for the telescope which allowed simultaneous guiding and spectroscopy. This component greatly improved the efficiency and reliability of the observations. I performed observations with this setup in an orchard in Salida from June 2002 to January 2003. I wrote a software package called "lambda" in the Interactive Data Language (IDL) which perfoms data processing and doppler shift measurements for the observations. I also performed similar measurements of the same data with the Image Reduction and Analysis Facility (IRAF) to double-check the results. In this poster I describe the results from the current observations with a particular emphasis on the radial velocity versus time and phase for the star Delta Cepheus.