HD 191939

HD 191939 is a single yellow (G-type) main-sequence star, located approximately 175 light-years away in the constellation of Draco, taking its primary name from its Henry Draper Catalogue designation.

HD 191939

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 5.75s[1]
Declination +66° 51′ 2.1″[1]
Apparent magnitude (V) 8.971[2]
Characteristics
HD 191939
Evolutionary stage main sequence star
Spectral type G0V[1] or G8V[3]
Astrometry
Radial velocity (Rv)+9.266 ± 0.0018[1] km/s
Proper motion (μ) RA: +150.256 [1] mas/yr
Dec.: -63.909 [1] mas/yr
Parallax (π)18.6247 ± 0.0253[1] mas
Distance175.1 ± 0.2 ly
(53.69 ± 0.07 pc)
Absolute magnitude (MV)5.32
Details
HD 191939
Mass0.92 M☉
Radius0.945[3] R☉
Luminosity (visual, LV)0.64 L☉
Surface gravity (log g)4.44 cgs
Temperature5400 K
Metallicity [Fe/H]-0.16 dex
Age7±3 Gyr
Other designations
HIP 99175, TYC 4244-964-1, USNO-A2 1500-07227721, 2MASS J20080574+6651019, Gaia DR2 2248126315275354496, TOI 1339
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

Characteristics

HD 191939 is a Sun-like G-type main-sequence star, likely older than the Sun and relatively depleted in metals.

Planetary system

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 gas giants,[3] all smaller than Neptune, in orbit around HD 191939. 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.[4]

The HD 191939 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 10.4±0.9[4] M🜨 0.089 +0.010
−0.012		 8.880411 +0.000069
−0.000069		 0 88.66° 3.37+0.13
−0.13 R🜨
c 7.2±1.4[4] M🜨 0.178 +0.033
−0.026		 28.58060 +0.00048
−+0.00045		 0 89.14° 3.22+0.15
−0.14 R🜨
d <5.8[4] M🜨 0.216 +0.011
−0.011		 38.3561 +0.0012
−0.0012		 0 89.49° 3.16+0.11
−0.11 R🜨
e 0.34±0.01[4] MJ 0.397±0.005 101.4±0.4 0 88.7±0.7° —
f 8-59 MJ — 3285-16790 — — —

See also

References
  1. HD 191939, entry, SIMBAD. Accessed online February 12, 2020.
  2. news.sky-map.org HD 191939 data
  3. Badenas-Agusti, Mariona; Günther, Maximilian N.; Daylan, Tansu; Mikal-Evans, Thomas; Vanderburg, Andrew; Huang, Chelsea X.; Matthews, Elisabeth; Rackham, Benjamin V.; Bieryla, Allyson; Stassun, Keivan G.; Kane, Stephen R.; Shporer, Avi; Fulton, Benjamin J.; Hill, Michelle L.; Nowak, Grzegorz; Ribas, Ignasi; Pallé, Enric; Jenkins, Jon M.; Latham, David W.; Seager, Sara; Ricker, George R.; Vanderspek, Roland K.; Winn, Joshua N.; Abril-Pla, Oriol; Collins, Karen A.; Pere Guerra Serra; Niraula, Prajwal; Rustamkulov, Zafar; Barclay, Thomas; et al. (2020). "HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away". The Astronomical Journal. 160 (3): 113. arXiv:2002.03958. doi:10.3847/1538-3881/aba0b5. S2CID 211069628.
  4. TESS-Keck Survey IX: Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian Plus a Distant Sub-Stellar Companion, 2021, arXiv:2108.02208





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