Epsilon Piscis Austrini
Star in the constellation Piscis Austrinus
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Epsilon Piscis Austrini, Latinized from ε Piscis Austrini, is a blue-white hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.17.[3] Based upon an annual parallax shift of 5.92mas as seen from the Gaia satellite, the system is located at a distance of roughly 550 light years.[2]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Piscis Austrinus[1] |
| Right ascension | 22h 40m 39.34826s[2] |
| Declination | â27° 02â² 37.0151â³[2] |
| Apparent magnitude (V) | +4.17[3] |
| Characteristics | |
| Evolutionary stage | subgiant[2] |
| Spectral type | B8 Ve[4] or B8 IVe[1] |
| UâB color index | â0.31[3] |
| BâV color index | â0.11[3] |
| Astrometry | |
| Radial velocity (Rv) | +1.1±2.8[5] km/s |
| Proper motion (μ) | RA: +21.839 mas/yr[2] Dec.: â1.588 mas/yr[2] |
| Parallax (Ï) | 5.9219±0.2931 mas[2] |
| Distance | 550 ± 30 ly (169 ± 8 pc) |
| Absolute magnitude (MV) | â1.66[1] |
| Details | |
| Mass | 5.95±0.30[6] Mâ |
| Radius | 7.51±0.38[6] Râ |
| Luminosity | 661[7] Lâ |
| Surface gravity (log g) | 3.93[8] cgs |
| Temperature | 11,066[7] K |
| Rotational velocity (v sin i) | 216[7] km/s |
| Other designations | |
| ε PsA, 18 Piscis Austrini, CDâ27°16010, FK5 854, HD 214748, HIP 111954, HR 8628, SAO 191318[9] | |
| Database references | |
| SIMBAD | data |
Characteristics
This is a B-type main sequence star with a stellar classification of B8 Ve.[4] It is a Be star that is spinning rapidly with a projected rotational velocity of 216 km/s,[7] compared to an equatorial critical velocity of 301 km/s.[8] The star has 6.0 times the mass of the Sun, 7.5 times the Sun's radius,[6] and is radiating 661 times the solar luminosity from its photosphere at an effective temperature of 11,066 K.[7]
Epsilon Piscis Austrini is part of a wide binary star system, the companion is likely a low-mass red dwarf with a projected separation of 11,700 astronomical units. It also exhibits a strong discrepancy between proper motion measurements taken by the Hipparcos and Gaia satellites, hinting the presence of an astrometric companion, possibly a solar-mass star, with a separation between 6 and 30 au.[6]
The star is moving through the Galaxy at 18.7 km/s relative to the Sun. Its projected Galactic orbit carries it between 23,917 and 28,138 light-years from the center of the Galaxy.[1]
Naming
In Chinese, ç¾½æè» (YÇ LÃn JÅ«n), meaning Palace Guard, refers to an asterism consisting of:
- ε Piscis Austrini
- 29 Aquarii
- 35 Aquarii
- 41 Aquarii
- 47 Aquarii
- 49 Aquarii
- λ Piscis Austrini
- HD 212448
- 21 Piscis Austrini
- 20 Piscis Austrini
- Ï Aquarii
- 68 Aquarii
- 66 Aquarii
- 61 Aquarii
- 53 Aquarii
- 50 Aquarii
- 56 Aquarii
- 45 Aquarii
- 58 Aquarii
- 64 Aquarii
- 65 Aquarii
- 70 Aquarii
- 74 Aquarii
- Ï2 Aquarii
- Ï1 Aquarii
- δ Aquarii
- 77 Aquarii
- 88 Aquarii
- 89 Aquarii
- 86 Aquarii
- 101 Aquarii
- 100 Aquarii
- 99 Aquarii
- 98 Aquarii
- 97 Aquarii
- 94 Aquarii
- Ï3Aquarii
- Ï2Aquarii
- Ï1Aquarii
- 87 Aquarii
- 85 Aquarii
- 83 Aquarii
- Ï Aquarii
- Ï1 Aquarii
- Ï2 Aquarii
Consequently, the Chinese name for ε Piscis Austrini itself is ç¾½æè»å « (YÇ LÃn JÅ«n bÄ, English: the Eighth Sixth Star of Palace Guard.)[10]