V692 Coronae Australis
SX Areits variable; Corona Australis / From Wikipedia, the free encyclopedia
V692 Coronae Australis (HD 166596; HR 6804; 3 G. CrA), or simply V692 CrA, is a whitish-blue hued variable star located in the southern constellation Corona Australis. It has a maximum apparent magnitude of 5.46,[2] making it faintly visible to the naked eye. The object is located relatively far at a distance of approximately 1,900 light years based on Gaia DR3 parallax measurements,[1] but it is approaching the Solar System with a fairly constrained heliocentric radial velocity of −15.3 km/s.[8] At its current distance, V692 CrA's brightness is heavily diminished by 0.46 magnitudes due to extinction due to interstellar dust.[18] Its absolute magnitude depends on the source: Westin (1985) gave a value of −6.44[9] while the extended Hipparcos catalogue gave a value of −2.26.[10]
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Corona Australis |
Right ascension | 18h 13m 12.69843s[1] |
Declination | −41° 20′ 09.9972″[1] |
Apparent magnitude (V) | 5.46[2] (5.46 - 5.51)[3] |
Characteristics | |
Spectral type | B2 III[4] or B1.5 IIIp[5] |
B−V color index | −0.17[6] |
Variable type | SX Arietis[7] |
Astrometry | |
Radial velocity (Rv) | −15.3±2.8[8] km/s |
Proper motion (μ) | RA: −2.050 mas/yr[1] Dec.: −6.210 mas/yr[1] |
Parallax (π) | 1.7423 ± 0.0977 mas[1] |
Distance | 1,900 ± 100 ly (570 ± 30 pc) |
Absolute magnitude (MV) | −6.44[9] or −2.26[10] |
Details | |
Mass | 7.35±0.48[11] M☉ |
Radius | 12.6±0.7[12] R☉ |
Luminosity (bolometric) | 4,181[11] L☉ |
Surface gravity (log g) | 3.52+0.33 −0.14[1] cgs |
Temperature | 17,061+1,474 −1,357[13] K |
Rotational velocity (v sin i) | 212±9[14] km/s |
Age | 31.6±5.1[15] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Astronomers Carlos and Mercedes Jaschek along with a colleague listed HD 166596 as a Be star in 1964.[20] However, its status as an Ap star was not observed until 1979 by astronomers N. Vogt and A.M Faundez.[21] A year later, HD 166596 was observed to be variable and it had a period of 1.67 days.[22] In 1981, its variability was confirmed and it was given the variable star designation V692 Coronae Australis—the 692nd variable star in Corona Australis.[23] The star might have a shorter period of 49.8 hours.[7]
V692 CrA has a stellar classification of B2 III[4] or B1.5 IIIp,[5] both indicating that it is a slightly evolved B-type giant star. The second classification indicates that V692 CrA has peculiarities in its spectrum. It has 7.35 times the mass of the Sun[11] and 12.6 times the Sun's radius.[12] It radiates at a bolometric luminosity 4,181 times that of the Sun[11] from its photosphere at an effective temperature of 17,061 K.[13] V692 CrA is estimated to be 31.6 million years old[15] and it spins rapidly with a projected rotational velocity of 212 km/s.[14]