Astronomy:HD 191939

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Short description: Star in the constellation Draco
HD 191939
300px
Location of HD 191939 in the night sky. The star is marked within the red diamond.
Observation data
Equinox J2000.0]] (ICRS)
Constellation Draco[1]
Right ascension  20h 08m 05.75515s[2]
Declination +66° 51′ 02.0766″[2]
Apparent magnitude (V) 8.971[3]
Characteristics
HD 191939
Evolutionary stage main sequence[2]
Spectral type G9V[4]
Astrometry
Radial velocity (Rv)−9.23±0.16[2] km/s
Proper motion (μ) RA: 150.194±0.015[2] mas/yr
Dec.: −63.988±0.017[2] mas/yr
Parallax (π)18.6967 ± 0.0133[2] mas
Distance174.4 ± 0.1 ly
(53.49 ± 0.04 pc)
Absolute magnitude (MV)+5.17[1]
Details[4]
HD 191939
Mass0.81±0.04 M☉
Radius0.94±0.02 R☉
Luminosity (bolometric)0.65±0.02 L☉
Surface gravity (log g)4.3±0.1 cgs
Temperature5348±100 K
Metallicity [Fe/H]−0.15±0.06 dex
Rotational velocity (v sin i)0.6±0.5[5] km/s
Age7±3[5] Gyr
Other designations
Gaia DR2 2248126315275354496, HD 191939, HIP 99175, TYC 4244-964-1, 2MASS J20080574+6651019[6]
Database references
SIMBADdata
Exoplanet Archive191939 data
Extrasolar Planets
Encyclopaedia		data

HD 191939 is a single yellow (G-type) main-sequence star, located approximately 174 light-years away in the northern constellation of Draco, taking its primary name from its Henry Draper Catalogue designation.

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 gaseous planets, all smaller than Neptune, in orbit around HD 191939.[5] 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] In 2022, a sixth planet, with a mass comparable to Uranus, was discovered in the system's habitable zone.[7] The 2021 study also suggested the possible presence of an additional non-transiting planet with a period of 17.7 days,[4] but the 2022 study did not support this.[7] The outermost planet, HD 191939 f, was better characterized in a 2026 study, which also presented astrometric measurements of its inclination and true mass: 98° and 4.8 MJ.[8]

The HD 191939 planetary system[7]
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[4]° —
g ≥13.5±2.0 M⊕ 0.812±0.028 284+10
−8 		0.030+0.025
−0.011 		— —
f 4.81+0.60
−0.77[8] MJ 		5.50+0.56
−0.71[8] 		5,100+760
−960[8] 		0.213+0.069
−0.064[8] 		98+12
−16[8]° 		—

See also

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ "HD 191939 - Star - SKY-MAP". http://news.sky-map.org/starview?object_type=1&object_id=1114234&object_name=HIP+99175&locale=KX. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Lubin, Jack et al. (2022). "TESS-Keck Survey. IX. Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian plus a Distant Substellar Companion". The Astronomical Journal 163 (2): 101. doi:10.3847/1538-3881/ac3d38. Bibcode: 2022AJ....163..101L. 
  5. ↑ 5.0 5.1 5.2 Badenas-Agusti, Mariona; Günther, Maximilian N.; Daylan, Tansu; Mikal-Evans, Thomas; Vanderburg, Andrew; Huang, Chelsea X.; Matthews, Elisabeth; Rackham, Benjamin V. et al. (2020). "HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away". The Astronomical Journal 160 (3): 113. doi:10.3847/1538-3881/aba0b5. Bibcode: 2020AJ....160..113B. 
  6. ↑ "HD 191939". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+191939. 
  7. ↑ 7.0 7.1 7.2 Orell-Miquel, J.; Nowak, G.; Murgas, F.; Palle, E.; Morello, G.; Luque, R.; Badenas-Agusti, M.; Ribas, I. et al. (2023). "HD 191939 revisited: New and refined planet mass determinations, and a new planet in the habitable zone". Astronomy & Astrophysics 669: A40. doi:10.1051/0004-6361/202244120. Bibcode: 2023A&A...669A..40O. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Xiao, Guang-Yao; Teng, Huan-Yu et al. (September 2026). "Transiting Planetary Systems with Distant Giant Companions Remain Moderately Coplanar". The Astrophysical Journal Letters. 

Coordinates: Sky map 20h 08m 5.75s, ++66° 51′ 2.1″

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