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.[2] 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.[3][4] These properties distinguish the SX Phoenicis variables from their cousins, the Delta Scuti variables. The latter have longer periods, higher metallicity and large amplitudes.[5]
SX Phoenicis variables are found primarily in globular clusters and galactic halos. The variability cycle has a period-luminosity relation.[6] All known SX Phoenicis variables in globular clusters are blue straggler stars.[7] These are stars that appear more blue (having a higher temperature) than the main sequence stars in the same cluster that have similar luminosities.[8]
List
editThe following list contains selected SX Phoenicis variable that are of interest to amateur or professional astronomy. Unless otherwise noted, the given magnitudes are in the V-band.[citation needed]
| Star |
Maximum magnitude |
Minimum magnitude |
Period (in days) |
Spectral type |
|---|---|---|---|---|
| SX Phoenicis[n 1] | 6.76 | 7.53 | 0.055 | A2V |
| KZ Hydrae | 9.46 | 10.26 | 0.060 | B9III/IV |
| DY Pegasi | 10.00 | 10.56 | 0.073 | F5 |
| CY Aquarii | 10.42 | 11.20 | 0.061 | B8 |
| AE Ursae Majoris[n 1] | 10.86 | 11.52 | 0.086 | A9 |
| XX Cygni | 11.28 | 12.13 | 0.135 | A5-F5 |
| BL Camelopardalis | 12.92 | 13.25 | 0.039 | |
| BX Sculptoris | 13.42 | 13.71 | 0.037 | A |
Notes
editReferences
edit- ^ Stankov, A.; Sinachopoulos, D.; Elst, E.; Breger, M. (February 2002). "Stromgren photometry of SX Phe = HD 223065". Communications in Asteroseismology. 141: 72–83. Bibcode:2002CoAst.141...72S. Retrieved 20 February 2022.
- ^ "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. S2CID 17310076.
- ^ 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. S2CID 17711408.