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Star in the constellation Draco From Wikipedia, the free encyclopedia
HD 191939 is a single yellow (G-type) main-sequence star, located approximately 174 light-years away in the constellation of Draco, taking its primary name from its Henry Draper Catalogue designation.
Location of HD 191939 in the night sky. The star is marked within the red diamond. | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Draco |
| Right ascension | 20h 08m 05.75515s[1] |
| Declination | +66° 51′ 02.0766″[1] |
| Apparent magnitude (V) | 8.971[2] |
| Characteristics | |
| HD 191939 | |
| Evolutionary stage | main sequence |
| Spectral type | G9V[3] |
| Astrometry | |
| Radial velocity (Rv) | −9.23±0.16[1] km/s |
| Proper motion (μ) | RA: 150.194±0.015 mas/yr[1] Dec.: −63.988±0.017 mas/yr[1] |
| Parallax (π) | 18.6967 ± 0.0133 mas[1] |
| Distance | 174.4 ± 0.1 ly (53.49 ± 0.04 pc) |
| Absolute magnitude (MV) | 5.32 |
| Details[3] | |
| HD 191939 | |
| Mass | 0.81±0.04 M☉ |
| Radius | 0.94±0.02 R☉ |
| Luminosity (bolometric) | 0.65±0.02 L☉ |
| Surface gravity (log g) | 4.3±0.1 cgs |
| Temperature | 5348±100 K |
| Metallicity [Fe/H] | −0.15±0.06 dex |
| Rotational velocity (v sin i) | 0.6±0.5[4] km/s |
| Age | 7±3[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 191939 is a Sun-like G-type main-sequence star, likely older than the Sun and relatively depleted in metals.
In 2020, an analysis carried out by a team of astronomers led by astronomer Mariona Badenas-Agusti of the TESS project confirmed the existence of three gaseous planets, all smaller than Neptune, in orbit around HD 191939.[4] Another non-transiting gas giant planet designated HD 191939 e was detected in 2021, along with a substellar object on a highly uncertain, 9 to 46 year orbit.[3] In 2022, a sixth planet, with a mass comparable to Uranus, was discovered in the system's habitable zone.[6] The 2021 study also suggested the possible presence of an additional non-transiting planet with a period of 17.7 days,[3] but the 2022 study did not support this.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.00±0.70 M🜨 | 0.0804+0.0025 −0.0023 |
8.8803256 | 0.031+0.010 −0.011 |
88.10+0.14 −0.10° |
3.410±0.075 R🜨 |
| c | 8.0±1.0 M🜨 | 0.1752+0.0055 −0.0050 |
28.579743 | 0.034+0.034 −0.013 |
89.10+0.06 −0.08° |
3.195±0.075 R🜨 |
| d | 2.80±0.60 M🜨 | 0.2132+0.0065 −0.0061 |
38.353037 | 0.031+0.018 −0.012 |
89.49+0.05 −0.08° |
2.995±0.070 R🜨 |
| e | ≥112.2±4.0 M🜨 | 0.407±0.012 | 101.12±0.13 | 0.031+0.008 −0.016 |
88.7±0.7[3]° | — |
| g | ≥13.5±2.0 M🜨 | 0.812±0.028 | 284+10 −8 |
0.030+0.025 −0.011 |
— | — |
| f | >2.08 MJ | >3.2 | >2200 | — | — | — |
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