HD 129899
Ap star in the constellation Apus
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HD 129899 (HIP 72670; 15 G. Apodis), is a solitary star located in the southern circumpolar constellation Apus, the bird-of-paradise. It has an apparent magnitude of 6.44,[2] placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively far at a distance of 928 light-years based on Gaia DR3 parallax measurements[1] and it is receding with a heliocentric radial velocity of 2.5 km/s.[6] At its current distance, HD 129899's brightness is heavily diminished by an interstellar extinction of 0.55 magnitudes[14] and it has an absolute bolometric magnitude of −1.28.[8]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 14h 51m 30.03619s[1] |
| Declination | −77° 10′ 33.4952″[1] |
| Apparent magnitude (V) | 6.44[2] (6.46 - 6.47)[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | Ap Si[5] |
| B−V color index | −0.03[2] |
| Variable type | suspected α2 CVn[3] |
| Astrometry | |
| Radial velocity (Rv) | 2.5±0.7[6] km/s |
| Proper motion (μ) | RA: −14.060 mas/yr[1] Dec.: −10.327 mas/yr[1] |
| Parallax (π) | 3.5129±0.028 mas[1] |
| Distance | 928 ± 7 ly (285 ± 2 pc) |
| Absolute magnitude (MV) | −0.57[7] |
| Absolute bolometric magnitude (Mbol) | −1.28[8] |
| Details | |
| Mass | 3.43±0.19[4] M☉ |
| Radius | 4.95[9] R☉ |
| Luminosity | 190+61 −46[10] L☉ |
| Surface gravity (log g) | 3.81[8] cgs |
| Temperature | 10,617+500 −479[10] K |
| Metallicity [Fe/H] | −0.01[11] dex |
| Rotation | 1.035 d[10] |
| Rotational velocity (v sin i) | 199±30[10] km/s |
| Age | 229+28 −25[4] Myr |
| Other designations | |
| 15 G. Apodis[12], CD−76°677, CPD−76°894, GC 19920, HD 129899, HIP 72670, SAO 257202, TIC 402517183[13] | |
| Database references | |
| SIMBAD | data |
HD 129899 has a stellar classification of ApSi,[5] indicating that it is an Ap star with an overabundance of silicon in its spectrum. It has 3.43 times the mass of the Sun[4] and 4.95 times the radius of the Sun.[9] It radiates 190 times the luminosity of the Sun from its photosphere at an effective temperature of 10,617 K,[10] giving it a bluish-white hue when viewed in the night sky. It has a near solar metallicity, having an iron abundance of [Fe/H] = −0.01 or 97.7% of the Sun's.[11] At the age of 229 million years, HD 129899 has completed 95% of its main sequence lifetime.[4] Unlike most chemically peculiar stars, HD 129899 spins rapidly with a rotational velocity of 199 km/s.[10]
The object was observed to be an Alpha2 Canum Venaticorum variable that fluctuates between 6.46 and 6.47 within 1.03 days,[3] which corresponds to the period of the rotation. However, this has not been confirmed. HD 129899 has a relatively weak magnetic field of approximately 402±48 gauss.[15]