XX Pyxidis

XX Pyxidis is a star located in the constellation Pyxis. It has an apparent magnitude that varies slightly at about 11.5, and is about 2,300 light years away.

XX Pyxidis

Visual band light curves for XX Pyxidis, adapted from Arentoft et al. (2001)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Pyxis
Right ascension	08h 58m 39.03s[2]
Declination	−24° 35′ 10.6″[2]
Apparent magnitude (V)	11.49[3]
Characteristics
Spectral type	A4V + M3V[4]
Variable type	Delta Scuti variable[3]
Astrometry
Proper motion (μ)	RA: −13.830[2] mas/yr Dec.: +6.985[2] mas/yr
Parallax (π)	1.4301±0.0341 mas[2]
Distance	2,280 ± 50 ly (700 ± 20 pc)
Orbit[4]
Period (P)	1.15 d
Eccentricity (e)	0.0
Inclination (i)	25-30°
Semi-amplitude (K1) (primary)	17.8±0.4 km/s
Details
Hot star
Mass	1.85±0.05[4] M☉
Radius	1.9[2] R☉
Luminosity	27[2] L☉
Surface gravity (log g)	4.21[2] cgs
Temperature	9,431[2] K
Metallicity [Fe/H]	+0.09[2] dex
Rotation	1.5 d[4]
Rotational velocity (v sin i)	52[5] km/s
Age	316[2] Myr
Cool star
Mass	0.3[4] M☉
Other designations
XX Pyxidis, CD−24 7599, GSC 06589-00261[6]
Database references
SIMBAD	data

XX Pyxidis is one of the more-studied members of a class of stars known as Delta Scuti variables^[4]—short-period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology.^[7] Astronomers made more sense of its pulsations when it became clear that it is also a binary star system. The main star is a white main sequence star of spectral type A4V that is around 1.85±0.05 times as massive as the Sun. Its companion is most likely a red dwarf star of spectral type M3V, around 0.3 times as massive as the Sun. The two are very close—possibly only 3 times the diameter of the Sun between them—and orbit each other every 1.15 days. The brighter star is deformed into an egg-shape,^[4] and pulsates in several overlapping modes 26-76 times per day.^[8]