SX Phoenicis Stars Suzanne Shuda Faculty Advisor: Dr. Oluseyi, Dept of Physics and Space Sciences, Florida Institute of Technology Introduction Methods and Design Results SX Phoenicis stars are usually found in I crossmatched the SDSS and SIMBAD A total of 42 SX Phoenicis stars were the outer regions of the galaxy which is databases to compile a list of likely SX found with metallicity measurements, called galactic halo. Their luminosity Phoenicis stars. I used SQL queries to much more than the previously known varies with a period of 1-2 hours. They display the information I wanted. I used 13 SX Phe stars. An O-C diagram are interesting because they are very old known characteristics such as spectral describes the observed minus but have not become white dwarfs as type and period to narrow down the stars calculated luminosity of a specific star. expected. Fewer than 20 field SX in the database. I learned the best queries The purpose is to study the long term Phoenicis stars are known to exist. By by experimenting with the suggestions in changes in luminosity. CY Aquarii, one studying these stars, we can learn about the tutorials on the website for SDSS. of the more well-known SX Phe stars how they formed, the makeup of the Using the data list from the SDSS which has been studied in the past. An galactic halo, and possibly locate dwarf Database, I crossmatched the list with the O-C diagram for CY Aquarii is shown in galaxies. The origin of SX Phe stars is SIMBAD database using the internal Fig 2. still unknown. function in SIMBAD. I also found the Conclusions/ Future Work metallicity of the stars in the databases. Fig 1: H-R diagram relates surface temperature The results show that there are very The metallicity or [Fe/H] is a measure of with luminosity. SX Phoenicis stars are located few SX Phoenicis stars in the galaxy the density of heavy elements within a in the instability strip, close to the main and very little data from them. By sequence. star. The metallicity can then be used to studying the metallicities, the origin of determine whether or not the star has these stars can be determined. If gone through s-process element there is a high metallicity, the star has enrichment and therefore determine the gone through s-process element origin of the star. enrichment and was most likely Fig 2: O-C formed by stellar cannibalism. If not, it diagram of CY was most likely formed through stellar Aquarii. Shows collisions. The methods used for this long-term experiment can be applied to any changes in the period other type of variable star. Other uses would be determining the overall metallicity of the galactic halo. .