Pi Arietis
Multiple star system in the constellation Aries
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Pi Arietis is a multiple star system in the northern constellation of Aries. Its name is a Bayer designation that is Latinized from π Arietis, and abbreviated Pi Ari or π Ari. Based upon parallax measurements made during the Hipparcos mission, this system is approximately 800 light-years (250 parsecs) distant from Earth,[2] and has an apparent visual magnitude of 5.314.[3] This is bright enough to be faintly seen with the naked eye. The position of this system near the ecliptic means it is subject to lunar occultation.[9]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries[1] |
| Right ascension | 02h 49m 17.55924s[2] |
| Declination | +17° 27′ 51.5168″[2] |
| Apparent magnitude (V) | 5.314[3] |
| Characteristics | |
| Spectral type | B6 V + A0 V + F8 V[4] |
| U−B color index | −0.47[5] |
| B−V color index | −0.06[5] |
| Astrometry | |
| Radial velocity (Rv) | +8.8±0.9[6] km/s |
| Proper motion (μ) | RA: +2.60 mas/yr[2] Dec.: −14.10 mas/yr[2] |
| Parallax (π) | 4.18±0.69 mas[2] |
| Distance | approx. 800 ly (approx. 240 pc) |
| Absolute magnitude (MV) | −1.56[1] |
| Details | |
| Mass | 4.4+0.55 −0.51[3] M☉ |
| Luminosity | 538[1] L☉ |
| Surface gravity (log g) | 4.5±0.25[3] cgs |
| Temperature | 16,000±1,000[3] K |
| Rotational velocity (v sin i) | 70[7] km/s |
| Age | 13+9 −6[3] Myr |
| Other designations | |
| π Ari, 42 Arietis, NSV 944, BD+16°355, GC 3378, HD 17543, HIP 13165, HR 836, SAO 93127, PPM 118581[8] | |
| Database references | |
| SIMBAD | data |
The primary member of this system is an intermediate-mass,[3] B-type main sequence star with a stellar classification of B6 V. It is a close, single-lined[10] spectroscopic binary with an orbital period of 3.854 days, an eccentricity of 0.04, and a combined visual magnitude of 5.30. At an angular separation of 3.28 arcseconds is a magnitude 8.46 A-type main sequence star with a classification of A0 Vp. Finally, a fourth member of the system is a magnitude 11.0 F-type main sequence star with a classification of F8V at an angular separation of 25.2 arcseconds from the primary.[4]
Name
This star, along with δ Ari, ε Ari, ζ Ari, and ρ3 Ari, were Al Bīrūnī's Al Buṭain (ألبطين), the dual of Al Baṭn, the Belly.[11] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Buṭain were the title for five stars : δ Ari as Botein, π Ari as Al Buṭain I, ρ3 Ari as Al Buṭain II, ε Ari as Al Buṭain III dan ζ Ari as Al Buṭain IV.[12]
In Chinese, 左更 (Zuǒ Gēng), meaning Official in Charge of the Forest, refers to an asterism consisting of π Arietis, ν Arietis, μ Arietis, ο Arietis and σ Arietis.[13] Consequently, the Chinese name for π Arietis itself is 左更五 (Zuǒ Gēng wu, English: the Fifth Star of Official in Charge of the Forest.)[14]