Global InformationBeta2 Sagittarii information
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 23m 13.13745s[1] |
| Declination | −44° 47′ 59.2051″[1] |
| Apparent magnitude (V) | +4.29[2] |
| Characteristics | |
| Spectral type | F2/3 V[3] or F2 III[4] |
| U−B color index | +0.07[2] |
| B−V color index | +0.34[2] |
| Astrometry | |
| Radial velocity (Rv) | +19.0[5] km/s |
| Proper motion (μ) | RA: +93.45[1] mas/yr Dec.: −54.09[1] mas/yr |
| Parallax (π) | 24.31 ± 0.19 mas[1] |
| Distance | 134 ± 1 ly (41.1 ± 0.3 pc) |
| Absolute magnitude (MV) | +1.20[6] |
| Details | |
| Mass | 1.43[7] M☉ |
| Luminosity | 20[8] L☉ |
| Surface gravity (log g) | 3.57[7] cgs |
| Temperature | 7,035±239[7] K |
| Metallicity [Fe/H] | −0.54[5] dex |
| Rotational velocity (v sin i) | 155[9] km/s |
| Age | 933[7] Myr |
| Other designations | |
Arkab Posterior, β2 Sgr, CD−45° 13171, HD 181623, HIP 95294, HR 7343, SAO 229654[10] | |
| Database references | |
| SIMBAD | data |
Beta2 Sagittarii (β2 Sagittarii, abbreviated Beta2 Sgr, β2 Sgr) is a star in the zodiac constellation of Sagittarius. It is visible to the naked eye, having an apparent visual magnitude of +4.29.[2] Based upon an annual parallax shift of 24.31 mas as seen from Earth,[1] it is located 134 light-years from the Sun.
Based upon variations in its proper motion, this is a probable astrometric binary system.[11] As such, its two components would be designated Beta2 Sagittarii A (officially named Arkab Posterior /ˈɑːrkæb pɒˈstɪəriər/, the traditional name of the system)[12][13] and B.
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Eggleton2008was invoked but never defined (see the help page). - ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
- ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.