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

History and nomenclature

The designation HD 191939 is from the Henry Draper Catalogue, which is based on spectral classifications made between 1911 and 1915 by Annie Jump Cannon and her co-workers, and was published between 1918 and 1924.

Characteristics

HD 191939 is a Sun-like G-type main-sequence star. It is 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 a three gas giants,[3] all smaller than Neptune, in orbit around HD 191939.

The HD 191939 planetary system[3]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ? M⊕ 0.089 +0.010
−0.012		 8.880411 +0.000069
−0.000069		 0 88.66° 3.37+0.13
−0.13 R⊕
c ? M⊕ 0.178 +0.033
−0.026		 28.58060 +0.00048
−+0.00045		 0 89.14° 3.22+0.15
−0.14 R⊕
d ? M⊕ 0.216 +0.011
−0.011		 38.3561 +0.0012
−0.0012		 0 89.49° 3.16+0.11
−0.11 R⊕
gollark: If a drone is going around ramming you you can just scrench it. If a drone drops HECf-251 on you, it can go high enough that you can't see it, drop it once, and fly away before you know what happened.
gollark: Yes, and it's very hard to defend against.
gollark: It has radars. By default those can only get your distance, but there's an option for providing coords and trilateration is a thing.
gollark: Computronics does, though.
gollark: That's a fair point. I don't think OC has stuff for that.

See also
  • List of extrasolar planets

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". arXiv:2002.03958 [astro-ph.EP].

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