| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Microscopium [1] |
| Right ascension | 21h 13m 03.06827s [2] |
| Declination | −39° 25′ 29.7097″ [2] |
| Apparent magnitude (V) | 5.26 [3] |
| Characteristics | |
| Evolutionary stage | main sequence [2] |
| Spectral type | F5 IV-V [4] or F6 V Fe−0.9 CH−0.5 [5] |
| B−V color index | +0.44 [3] |
| Astrometry | |
| Radial velocity (Rv) | −41±1 [6] km/s |
| Proper motion (μ) | RA: +185.855 mas/yr [2] Dec.: −113.449 mas/yr [2] |
| Parallax (π) | 29.2823±0.0827 mas [2] |
| Distance | 111.4 ± 0.3 ly (34.15 ± 0.10 pc) |
| Absolute magnitude (MV) | +2.66 [1] |
| Details | |
| Mass | 1.5 [2] M☉ |
| Radius | 2.18±0.09 [7] R☉ |
| Luminosity | 7.83±0.04 [2] L☉ |
| Surface gravity (log g) | 3.91±0.09 [8] cgs |
| Temperature | 6,519±80 [9] K |
| Metallicity [Fe/H] | −0.18±0.03 [10] dex |
| Rotational velocity (v sin i) | 10 [11] km/s |
| Age | 2.23±0.04 Gyr |
| Other designations | |
| 56 G. Microscopii [12] , CD−39°14152, CPD−39°8898, GC 29640, HD 201772, HIP 104738, HR 8104, SAO 212793, LTT 8413 [13] | |
| Database references | |
| SIMBAD | data |
HD 201772, also known as HR 8104, is a yellowish-white hued star located in the southern constellation of Microscopium. It has an apparent magnitude of 5.26, [3] making it one of the brighter members of this generally faint constellation. The object is located relatively close at a distance of 111 light-years based on Gaia DR3 parallax measurements [2] but is approaching closer with a heliocentric radial velocity of −41 km/s . [6] At its current distance, HD 201772's brightness is diminished by 0.11 magnitudes due to interstellar dust. [14]
The star has been given multiple stellar classifications over the years. It was given the luminosity class of a subgiant and main sequence star (IV/V; IV-V) [15] [4] and a dwarf (V). [16] [17] Most sources generally agree that it is a F5 star. Richard O. Gray and colleagues give HD 201772 a class of F6 V Fe−0.9 CH−0.5, which indicates that it is a F-type main-sequence star with an underabundance of iron and CH molecules in its spectrum. [5]
It has 1.47 times the mass of the Sun [18] and an enlarged radius of 2.2 R☉. [7] It radiates 7.8 times the luminosity of the Sun from its photosphere at an effective temperature of 6,519 K . [9] At an age of 2.5 billion years, HD 201722 is currently 1.33 magnitudes above the ZAMS, consistent with a star that is evolving off the main sequence. [11] The star has an iron abundance 66% that of the Sun, [10] making it metal deficient. It spins modestly with a projected rotational velocity of 10 km/s . [11]
HD 201772 is suspected to be a spectroscopic binary consisting of the subgiant described above and an ordinary F6 V star with a mass of 1.31 M☉. [19] However, the stars have no separation or an orbital period. [20] This is because the companion might be a result of spectrum contamination, so HD 201772 is more likely to be a solitary star. [21]