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.^[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]

A visual band light curve for SX Phoenicis, adapted from Stankov et al. (2002)^[1]

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

The 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

1. double-mode