Eta2 Coronae Australis
Star in the constellation Corona Austrlis
From Wikipedia, the free encyclopedia
Eta2 Coronae Australis is a solitary star[14] located in the southern constellation of Corona Australis. Its name is a Bayer designation that is Latinized from η2 Coronae Australis, and abbreviated Eta2 CrA or η2 CrA. This object is faintly visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.59.[3] Gaia DR3 parallax measurements imply a distance of 770 light-years (235 pc) from the Sun,[2] but it is drifting closer with a radial velocity of −23 km/s.[7] At its current distance Eta2 CrA's brightness is diminished by 0.27 magnitudes due to stellar extinction from interstellar dust[15] and it has an absolute magnitude of −0.24.[1]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Corona Australis[1] |
| Right ascension | 18h 49m 34.99649s[2] |
| Declination | −43° 26′ 02.7522″[2] |
| Apparent magnitude (V) | 5.59±0.01[3] |
| Characteristics | |
| Evolutionary stage | main sequence star[4] |
| Spectral type | B9 IV[5] |
| B−V color index | −0.08[6] |
| Astrometry | |
| Radial velocity (Rv) | −23.0±4.3[7] km/s |
| Proper motion (μ) | RA: −2.963 mas/yr[2] Dec.: −25.374 mas/yr[2] |
| Parallax (π) | 4.2500±0.1158 mas[2] |
| Distance | 770 ± 20 ly (235 ± 6 pc) |
| Absolute magnitude (MV) | −0.24[1] |
| Details | |
| Mass | 3.23±0.08[4] M☉ |
| Radius | 5.82±0.31[8] R☉ |
| Luminosity | 171+20 −18[4] L☉ |
| Surface gravity (log g) | 3.47[9] cgs |
| Temperature | 10,940±255[4] K |
| Metallicity [Fe/H] | +0.06[9] dex |
| Rotational velocity (v sin i) | 30[10] km/s |
| Age | 213[11] Myr |
| Other designations | |
| Eta2 CrA, 26 G. Coronae Australis[12], CD−43°12854, CPD−43°8779, GC 25766, HD 173861, HIP 92382, HR 7068, SAO 229307[13] | |
| Database references | |
| SIMBAD | data |
This object has a stellar classification of B9 IV,[5] suggesting that is a slightly evolved a B-type subgiant star. However, Zorec & Royer (2012) model it to be a dwarf star that has completed 80.4% of its main sequence lifetime.[4] It is estimated to be 213 million years old[11] and is spinning with a projected rotational velocity of 30 km[10] The star has a mass that is 3.23 times that of the Sun,[4] and 5.82 times the Sun's radius.[8] It is radiating 171 times the luminosity of the Sun[4] from its photosphere at an effective temperature of 10,940 K.[4]
Eta2 CrA has a near-solar metallicity at [Fe/H] = +0.06.[9] Some earlier catalogues listed the object as a chemically peculiar star but that status is now considered to be doubtful.[16]