HD 191939

Short description: Star in the constellation Draco

HD 191939

Location of HD 191939 in the night sky. The star is marked within the red diamond.

Observation data
Epoch J2000.0 Equinox (celestial coordinates)
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[1] mas/yr
Dec.: −63.988±0.017[1] mas/yr
Parallax (π)| 18.6967 ± 0.0133[1] mas
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

Gaia DR2 2248126315275354496, HD 191939, HIP 99175, TYC 4244-964-1, 2MASS J20080574+6651019[5]

Database references
SIMBAD| data
Exoplanet Archive| data
Extrasolar Planets
Encyclopaedia| data

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.

## Contents

* 1 Characteristics
* 2 Planetary system
* 3 See also
* 4 References

## 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.[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]

The HD 191939 planetary system[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  | —  | —  | —

## See also

* List of extrasolar planets
* List of exoplanets discovered in 2020 (HD 191939 b, c and d)
* List of exoplanets discovered in 2021 (HD 191939 e)
* List of exoplanets discovered in 2022 (HD 191939 f & g)

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 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.
2. ↑ "HD 191939 - Star - SKY-MAP". http://news.sky-map.org/starview?object_type=1&object_id=1114234&object_name=HIP+99175&locale=KX.
3. ↑ 3.0 3.1 3.2 3.3 3.4 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.
4. ↑ 4.0 4.1 4.2 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.
5. ↑ "HD 191939". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+191939.
6. ↑ 6.0 6.1 6.2 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.

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

* v
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* e

2020 in space

* « 2019

2021 »

Space probe launches |

* Solar Orbiter (Feb 2020)
* Hope Mars Mission (Jul 2020)
* Tianwen-1 (Jul 2020)
* Mars 2020 (Jul 2020)
* Perseverance
* Mars Helicopter Ingenuity
* Chang'e 5 (lunar sample return mission; Oct 2020)

Selected NEOs|

* Asteroid close approaches
* 2020 BX12
* 2020 CD3 (temporary satellite)
* (52768) 1998 OR2
* 2020 JJ
* 2020 LD
* (163348) 2002 NN4
* 2011 ES4
* 2018 VP1
* (501647) 2014 SD224

Exoplanets |

* AU Mic b
* Gliese 229 Ac
* Gliese 433 (b * c * d)
* GJ 1151 b radio emissions
* Kepler-160d
* Kepler-1649c
* Lacaille 9352 (b * c)
* TOI 700 (b * c * d)
* TOI 732 (b * c)
* TOI 1338 b
* TOI 1339 (b * c * d)

Discoveries|

* 2020 AV2
* FRB 180916 source location and periodicity
* Radcliffe wave
* Ophiuchus Supercluster explosion
* PSO J03094+27
* 2MASS J10475385+2124234 wind speed measurements
* SGR 1935+2154
* HR 6819 black hole
* SWIFT J1818.0–1607
* South Pole Wall

Comets |

* C/2019 Y4 (ATLAS)
* C/2017 T2 (PANSTARRS)
* C/2020 F8 (SWAN)
* C/2019 U6 (LEMMON)
* C/2020 F3 (NEOWISE)
* 2P/Encke
* 88P/Howell

Space exploration|

* Spitzer retirement (Jan)
* BepiColombo (Earth gravity assist; Apr)
* OSIRIS-REx (collecting sample from asteroid Bennu; Oct)
* Hayabusa2 (sample return from asteroid Ryugu to Earth; Dec)

* Category:2019 in space — Category:2020 in space — Category:2021 in space

Template:2021 in space

* v
* t
* e

Draco constellation

Stars
(list)|

| Bayer|

* α (Thuban)
* β (Rastaban)
* γ (Eltanin)
* δ (Altais)
* ε (Tyl)
* ζ (Aldhibah)
* η (Athebyne)
* θ
* ι (Edasich)
* κ
* λ (Giausar)
* μ (Alrakis)
* ν (Kuma)
* ξ (Grumium)
* ο
* π
* ρ
* σ (Alsafi)
* τ
* υ
* φ
* χ
* ψ1 (Dziban)
* ψ2
* ω

|

Flamsteed|

* 6
* 7 (Tianyi)
* 8 (Taiyi)
* 10 (i)
* 15 (A)
* 18 (g)
* 19 (h)
* 26
* 36
* 39 (b)
* 42 (Fafnir)
* 45 (d)
* 64 (e)
* 68

Variable|

* AG
* BY
* CL
* CM

HR|

* 3751
* 4126
* 5811
* 6237
* 6618 (Alruba)
* 6817
* 7137
* 7783

HD|

* 81817
* 101364

Gliese|

* Gliese 420
* Gliese 625
* Gliese 687

Kepler|

* 1
* 4
* 10
* 12
* 90
* 296

Other|

* G 240-72
* GD 356
* GRW +70 8247
* LP 71-82
* 2M 1237+6526
* Struve 2398
* WISE 1647+5632

Star clusters|

| Stellar streams|

* LAMOST 1

|

Nebulae|

| Planetary|

* Cat's Eye Nebula

|

Galaxies|

| NGC|

* 3147
* 4121
* 4125
* 4236
* 4319
* 4345
* 4513
* 5866
* 5879
* 5907
* 5949
* 5965
* 5982
* 5985
* 6090
* 6248
* 6285
* 6286
* 6340
* 6373
* 6394
* 6412
* 6503
* 6566
* 6621
* 6670
* 6786

|

Other|

* 3C 249.1
* 3C 305
* 3C 319
* 3C 371
* 3C 390.3
* 3C 401
* H1821+643
* HFLS3
* PGC 39058

Galaxy clusters|

* Abell 2218
* CL1358+62

Other|

* GRB 110328A
* SN 2005B
* Draco Supercluster

* List

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Original source: https://en.wikipedia.org/wiki/HD 191939. Read more

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