SX Phoenicis variable
An SX Phoenicis variable is a type of variable star. These stars exhibit a short period pulsation behavior that varies on time scales of 0.03–0.08 days (0.7–1.9 hours). They have spectral classifications in the range A2-F5 and vary in magnitude by up to 0.7. Compared to the Sun, these stars have a lower metallicity, which means they have a reduced abundance of elements other than hydrogen and helium. They also have relatively high space velocity and low luminosities for stars of their stellar classification. These properties distinguish the SX Phoenicis variables from their cousins, the Delta Scuti variables. The latter have longer periods, strong metallicity and large amplitudes.
SX Phoenicis variables are found primarily in globular clusters and galactic halos. The variability cycle has a periodicity-luminosity relation. All known SX Phoenicis variables in globular clusters are blue straggler stars. These are stars that appear more blue (having a higher temperature) than the main sequence stars in the same cluster that have similar luminosities.
A well known SX Phoenicis is CY Aquarii
- "GCVS Variability Types". General Catalogue of Variable Stars. Moscow, Russia: Russian Foundation for Basic Research, Sternberg Astronomical Institute. Retrieved 2010-03-17.
- Burki, G.; Mayor, M. (1986). "Radial velocities with CORAVEL - Results on stellar variability and duplicity". Instrumentation and research programmes for small telescopes; Proceedings of the IAU Symposium. Christchurch, New Zealand: Dordrecht, D. Reidel Publishing Co. p. 392. Bibcode:1986IAUS..118..385B.
- Breger, M. (Jan 1980). "The nature of dwarf Cepheids. V - Analysis and conclusions". Astrophysical Journal, Part 1 235: 156. Bibcode:1980ApJ...235..153B. doi:10.1086/157620.
- McNamara, D. H. (-April 1995). "Period-luminosity relations of SX Phoenicis stars". Astronomical Journal 109 (4): 1751–1756. Bibcode:1995AJ....109.1751M. doi:10.1086/117405.
- Templeton, Matthew. "Variable Star of the Season: Delta Scuti and the Delta Scuti variables". American Association of Variable Star Observers.
- Jeon, Young-Beom; Lee, Myung Gyoon; Kim, Seung-Lee; Lee, Ho (July 2004). "SX Phoenicis Stars in the Globular Cluster NGC 5466". The Astronomical Journal 128 (1): 11. arXiv:astro-ph/0404069. Bibcode:2004AJ....128..287J. doi:10.1086/421735.
- Santolamazza, P.; Marconi, M.; Bono, G.; Caputo, F.; Cassisi, S.; Gilliland, R. L. (June 2001). "Linear Nonadiabatic Properties of SX Phoenicis Variables". The Astrophysical Journal 554 (2): 1124–1140. arXiv:astro-ph/0102029. Bibcode:2001ApJ...554.1124S. doi:10.1086/321408.