| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 02h47m 54.54142s[1] |
| Declination | +29° 14′ 49.6132″[1] |
| Apparent magnitude (V) | 4.514[2] |
| Characteristics | |
| Spectral type | K1.5 III[3] |
| U−B color index | +1.083[2] |
| B−V color index | +1.118[2] |
| R−I color index | 0.58 |
| Astrometry | |
| Radial velocity (Rv) | –15.53 ± 0.14[4] km/s |
| Proper motion (μ) | RA: +149.47 ± 0.25[1] mas/yr Dec.: –127.05 ± 0.18[1] mas/yr |
| Parallax (π) | 19.01 ± 0.21 mas[1] |
| Distance | 172 ± 2 ly (52.6 ± 0.6 pc) |
| Details | |
| Mass | 1.6[5] M☉ |
| Radius | 11.1 ± 0.8[3] R☉ |
| Luminosity | 56[4] L☉ |
| Surface gravity (log g) | 2.7[4] cgs |
| Temperature | 4,603[4] K |
| Metallicity [Fe/H] | –0.02[4] dex |
| Rotational velocity (v sin i) | 4.5[4] km/s |
| Other designations | |
Lilii Borea, BD+28° 462, HD 17361, HIP 13061, HR 824, SAO 75578.[6] | |
| Database references | |
| SIMBAD | data |
39 Arietis (abbreviated 39 Ari), officially named Lilii Borea /ˈlɪliaɪ ˈbɔːriə/,[7] is a star in the northern constellationofAries. It is visible to the naked eye with an apparent visual magnitude of +4.5.[2] The distance to this star, as determined from an annual parallax shift of 19.01 mas,[1] is approximately 172 light-years (53parsecs). This star was formerly located in the obsolete constellation Musca Borealis.
39 Arietis is the star's Flamsteed designation.
This star was described as Lilii BoreabyNicolas-Louis de Lacaille in 1757,[8][9] as a star of the now-defunct constellation of Lilium (the Lily). The words are simply the Latin phrase Līliī Boreā 'in the north of Lilium'. Līliī Austrīnā /ɔːˈstraɪnə/ 'in the south of Lilium' was 41 Arietis.
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalog and standardize proper names for stars. The WGSN approved the name Lilii Borea for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[7]
InChinese, 胃宿 (Wèi Su), meaning Stomach, refers to an asterism consisting of 39 Arietis, 35 Arietis and 41 Arietis.[11] Consequently, the Chinese name for 39 Arietis itself is 胃宿二 (Wèi Su èr, English: the Second Star of Stomach).[12]
39 Arietis is a giant star with a stellar classification of K1.5 III.[3] It is currently at an evolutionary stage known as the red clump, indicating that it is generating energy through the fusion of helium at its core.[5] It has 1.6[5] times the mass of the Sun, but its outer envelope has expanded to around 11[3] times the Sun's radius. It shines with 56 times the luminosity of the Sun.[4] This energy is being radiated into outer space from its outer atmosphere at an effective temperature of 4,603 K,[4] giving it the cool orange-hued glow of a K-type star.[13]
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