| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Apus |
| Right ascension | 17h 57m 41.686s [1] |
| Declination | −76° 10′ 40.62″ [1] |
| Apparent magnitude (V) | 6.07±0.01 [2] |
| Characteristics | |
| Evolutionary stage | red giant branch [3] |
| Spectral type | K2 III [4] |
| U−B color index | +1.28 [5] |
| B−V color index | +1.20 [5] |
| Astrometry | |
| Radial velocity (Rv) | +36.8±0.4 [6] km/s |
| Proper motion (μ) | RA: +2.464 mas/yr [1] Dec.: −1.867 mas/yr [1] |
| Parallax (π) | 5.2546±0.022 mas [1] |
| Distance | 621 ± 3 ly (190.3 ± 0.8 pc) |
| Absolute magnitude (MV) | −0.26 [7] |
| Details | |
| Mass | 3.05 [8] M☉ |
| Radius | 20.8 [9] R☉ |
| Luminosity | 185 [10] L☉ |
| Surface gravity (log g) | 2.04±0.02 [3] cgs |
| Temperature | 4,498 [10] K |
| Metallicity [Fe/H] | −0.13 [11] dex |
| Rotational velocity (v sin i) | 2.1±1.3 [12] km/s |
| Other designations | |
| 63 G. Apodis [13] , CD−76°919, CPD−76 1226, HD 161988, HIP 87926, HR 6635, SAO 257542, WDS J17577-7611A [14] | |
| Database references | |
| SIMBAD | data |
HD 161988, also known as HR 6635, is a solitary, orange hued star located in the southern circumpolar constellation Apus. It has an apparent magnitude of 6.07, [2] allowing it to be faintly visible to the naked eye. Parallax measurements place it at a distance of 621 light years, [1] and it is currently receding with a heliocentric radial velocity of 36.8 km/s . [6]
The object has a stellar classification of K2 III, [4] indicating that it is a red giant. Gaia Data Release 3 models place it on the red giant branch. At present it has 3.05 times the mass of the Sun [8] and an enlarged radius of 20.8 R☉ . [9] It shines at 185 times the luminosity of the Sun from its photosphere at an effective temperature of 4,498 K . [10] HD 161988 has an iron abundance 74% that of the Sun, [11] making it slightly metal deficient. Like most giants, it spins modestly with a projected rotational velocity of 2.1 km/s . [12]
HD 161988 has a 14th magnitude optical companion located 26.4 arcseconds away along a position angle of 122°. [15]