HD 190007

HD 190007

Four representative light curves for HD 190007, adapted from Burt et al. (2020)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Aquila[2]
Right ascension	20^h 02^m 47.04569^s[3]
Declination	+03° 19′ 34.2658″[3]
Apparent magnitude (V)	7.46[1]
Characteristics
Evolutionary stage	main sequence[4]
Spectral type	K5 V[5]
U−B color index	+1.09[6]
B−V color index	+1.11[6]
Variable type	BY Dra[7]
Astrometry
Radial velocity (Rv)	−30.268±0.0013[8] km/s
Proper motion (μ)	RA: −90.383 mas/yr[3] Dec.: 119.430 mas/yr[3]
Parallax (π)	78.6465 ± 0.0198 mas[3]
Distance	41.47 ± 0.01 ly (12.715 ± 0.003 pc)
Absolute magnitude (MV)	6.91[2]
Details
Mass	0.77±0.02[1] M☉
Radius	0.80[9] R☉
Luminosity	0.24[9] L☉
Surface gravity (log g)	4.50[10] cgs
Temperature	4,610±20[1] K
Metallicity [Fe/H]	0.16[10] dex
Rotation	28.626±0.046 d[1]
Other designations
V1654 Aql, BD+02°4076, GJ 775, HD 190007, HIP 98698, SAO 125379[11]
Database references
SIMBAD	data
ARICNS	data

HD 190007, also known as Gliese 775, is a star with a close orbiting exoplanet in the constellation of Aquila. Parallax measurements by Gaia put the star at a distance of 41.5 light-years (12.7 parsecs) away from the Sun. It is drifting closer with a radial velocity of −30.3 km/s,[8] and is predicted to come within 11.8 light-years in 375,000 years.[12] The star has an absolute magnitude of 6.91,[2] but at its present distance the apparent visual magnitude is 7.46,[1] which is too faint to be viewed with the naked eye.

The variability of the brightness of HD 190007 was discovered by George Wesley Lockwood et al. from data taken during a photometry program at Lowell Observatory carried out from 1984 through 1995.[13] It was given its variable star designation, V1654 Aquilae, in 1997.[14]

The spectrum of HD 190007 matches a K-type main-sequence star with a stellar classification of K5 V.[5] It is classified as a BY Draconis variable, showing a moderate level of magnetic activity in its chromosphere[4] with a suspected activity cycle lasting 13.7 years.[15] The star displays a mild enhancement of metals and its age is uncertain. It has 77%[1] of the mass of the Sun, 80% of the Sun's radius,[9] and is spinning with a rotation period of 28.6 days.[1] HD 190007 is radiating 24%[9] of the luminosity of the Sun from its photosphere at an effective temperature of 4,610 K.[1]

Planetary system

The exoplanet HD 190007 b on a close orbit was first detected in 2020 by the radial-velocity method.[1] Between 2015 and 2019, the Roque de los Muchachos Observatory in the Canary Islands observed HD 190007 to accumulate 37 spectrographs. This, combined with 33 spectrographs from the W. M. Keck Observatory in Hawaii over 6 years (1998 to 2014), flux measurements from the Fairborn Observatory in Arizona over 20 years, and a two-minute cadence with the Transiting Exoplanet Survey Satellite in 2022 provided the data to update the exoplanetary parameters by M. Stalport and associates in 2023.[4]

As the inclination of the orbital plane is uncertain, only a lower bound on the exoplanet mass can be determined. It has at least 15.5 times the mass of the Earth. It is orbiting close to its parent star with a moderate eccentricity and a period of just 11.7 days.

The HD 190007 planetary system[1][4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥15.5+1.2 −1.3 M🜨	0.092±0.0008	11.724128(99)	0.136+0.085 −0.080	—	—

See also

• List of exoplanets discovered in 2023 – HD 190007 b

References

1. Burt, Jennifer; et al. (2021). "A Collage of Small Planets from the Lick–Carnegie Exoplanet Survey: Exploring the Super-Earth and Sub-Neptune Mass Regime". The Astronomical Journal. 161 (1): 10. arXiv:2011.08867. Bibcode:2021AJ....161...10B. doi:10.3847/1538-3881/abc2d0. S2CID 227013469.
2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
3. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
4. Stalport, M.; et al. (August 2023). "A review of planetary systems around HD 99492, HD 147379 and HD 190007 with HARPS-N". Astronomy & Astrophysics. 678: A90. arXiv:2308.05669. Bibcode:2023A&A...678A..90S. doi:10.1051/0004-6361/202346887. S2CID 260775534. A90.
5. Kirkpatrick, J. D.; et al. (1991). "A standard stellar spectral sequence in the red/near-infrared - Classes K5 to M9". Astrophysical Journal Supplement Series. 77: 417. Bibcode:1991ApJS...77..417K. doi:10.1086/191611.
6. J.-C., Mermilliod (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
7. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
8. Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
9. Chandler, Colin Orion; et al. (2016). "The Catalog of Earth-Like Exoplanet Survey Targets (CELESTA): A Database of Habitable Zones Around Nearby Stars". The Astronomical Journal. 151 (3): 59. arXiv:1510.05666. Bibcode:2016AJ....151...59C. doi:10.3847/0004-6256/151/3/59. S2CID 119246448.
10. Mishenina, T. V.; et al. (2013). "Abundances of neutron-capture elements in stars of the Galactic disk substructures". Astronomy & Astrophysics. 552: A128. arXiv:1303.1730. Bibcode:2013A&A...552A.128M. doi:10.1051/0004-6361/201220687. S2CID 119268097.
11. "HD 190007". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 4 September 2017.
12. Bailer-Jones, C.A.L.; et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv:1805.07581. Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456. S2CID 56269929.
13. Lockwood, G. W.; Skiff, Brian A.; Radick, Richard R. (August 1997). "The Photometric Variability of Sun-like Stars: Observations and Results, 1984-1995". The Astrophysical Journal. 485 (2): 789–811. Bibcode:1997ApJ...485..789L. doi:10.1086/304453. Retrieved 22 November 2024.
14. Kazarovets, E. V.; Kireeva, N. N.; Samus, N. N.; Durlevich, O. V/ (May 2003). "The 77th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 5422 (1–56): 1. Bibcode:2003IBVS.5422....1K. Retrieved 22 November 2024.
15. Obridko, V. N.; et al. (October 2022). "Solar and stellar activity cycles - no synchronization with exoplanets". Monthly Notices of the Royal Astronomical Society. 516 (1): 1251–1255. arXiv:2208.06190. Bibcode:2022MNRAS.516.1251O. doi:10.1093/mnras/stac2286.

External links

• Sol Station: http://www.solstation.com/stars3/100-ks.htm Archived 2017-12-24 at the Wayback Machine