V701 Coronae Australis

V701 Coronae Australis (HD 176723; HR 7197; 40 G. Coronae Australis), or simply V701 CrA, is a solitary,^[16] yellowish-white hued variable star located in the southern constellation Corona Australis. It has an average apparent magnitude of 5.72,^[17] making it faintly visible to the naked eye under ideal conditions. The object is located relatively close at a distance of 213 light-years based on Gaia DR3 parallax measurements,^[1] and it is currently receding with a poorly constrained heliocentric radial velocity of 4 km/s.^[6] At its current distance, V701 CrA's brightness is diminished by a quarter of a magnitude due to extinction^[18] and it has an absolute magnitude of +1.55.^[7]

A light curve for V701 Coronae Australis, plotted from TESS data^[19]

V701 Coronae Australis

Location of HD 168592 (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Corona Australis
Right ascension	19h 03m 17.69619s[1]
Declination	−38° 15′ 11.3335″[1]
Apparent magnitude (V)	5.69 to 5.73[2]
Characteristics
Spectral type	F2 III/IV[3] or F0 IIIn[4]
B−V color index	+0.32[5]
Variable type	δ Scuti[2]
Astrometry
Radial velocity (Rv)	4±7.4[6] km/s
Proper motion (μ)	RA: +12.794 mas/yr[1] Dec.: +14.271 mas/yr[1]
Parallax (π)	15.2952±0.0559 mas[1]
Distance	213.2 ± 0.8 ly (65.4 ± 0.2 pc)
Absolute magnitude (MV)	+1.55[7]
Details
Mass	1.83+0.07 −0.06[8] M☉
Radius	2.85±0.14[9] R☉
Luminosity	17.5+0.2 −0.1[1] L☉
Surface gravity (log g)	3.75±0.12[10] cgs
Temperature	7,046±240[11] K
Metallicity [Fe/H]	−0.21[12] dex
Rotational velocity (v sin i)	265[13] km/s
Age	1.25[11] Gyr
Other designations
40 G. Coronae Australis[14], V701 CrA, CD−38°13300, CPD−38°7685, GC 26177, HD 176723, HIP 93552, HR 7197, SAO 210859[15]
Database references
SIMBAD	data

The object was first suspected to be variable in 1990. The variations matched that of δ Scuti variables.^[20] Three years later, it was confirmed to be variable and was given the variable star designation V701 Coronae Australis.^[21] It ranges from magnitude 5.69 to 5.73^[2] within 3.25 hours.^[22]

V701 CrA has a stellar classification of F2 III/IV,^[3] indicating that it is an evolved F-type star with the blended luminosity class of a subgiant and giant star. It has also been given a class of F0 IIIn,^[4] indicating broad or nebulous absorption lines due to rapid rotation. It has 1.83 times the mass of the Sun^[8] and a slightly enlarged radius of 2.85 R_☉.^[9] It radiates 17.5 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 7,046 K.^[11] The star spins rapidly with a projected rotational velocity of 265 km/s,^[13] which causes it to have an equatorial bulge that is 26% larger than the poles.^[23] It is metal deficient with an iron abundance 62% that of the Sun ([Fe/H] = −0.21)^[12] and it is estimated to be 1.25 billion years old.^[11] V701 CrA was considered to be a chemically peculiar star and was given a class of FpSr. Its peculiarity is now considered to be doubtful.^[24]