HD_195019 Latitude and Longitude:
Sky map 20h 28m 18.6363s, +18° 46′ 10.188″
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HD 195019
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Delphinus
Right ascension 20h 28m 18.6367s [1]
Declination +18° 46′ 10.180″ [1]
Apparent magnitude (V) 6.97 + 10.60 [2]
Characteristics
Spectral type G1V [3] + K3: [4]
B−V color index 0.662±0.007 [5]
Astrometry
Radial velocity (Rv)−91.290±0.0039 [6] km/s
Proper motion (μ) RA: 349.620(16)  mas/ yr [1]
Dec.: −56.618(19)  mas/ yr [1]
Parallax (π)26.6465 ± 0.0225  mas [1]
Distance122.4 ± 0.1  ly
(37.53 ± 0.03  pc)
Absolute magnitude (MV)4.01 [5]
Details [7]
HD 195019 A
Mass1.08±0.01 [8]  M☉
Radius1.47±0.04 [8]  R☉
Luminosity2.23±0.02 [8]  L☉
Surface gravity (log g)4.13±0.02 [8]  cgs
Temperature5,825±56 [8]  K
Metallicity [Fe/H]0.068±0.030 [9]  dex
Rotational velocity (v sin i)2.47±0.50 [9] km/s
Age7.7±0.7 [8]  Gyr
HD 195019 B
Mass0.7 [10]  M☉
Surface gravity (log g)4.46 [11]  cgs
Temperature4,652 [11]  K
Rotational velocity (v sin i)1.71 [11] km/s
Other designations
BD+18° 4505, Gaia DR2 1815418118373631360, HD 195019, HIP 100970, SAO 106138, WDS J20283+1846A, LTT 15981, NLTT 49312, GCRV 12790, 2MASS J20281860+1846103 [12]
Database references
SIMBAD data

HD 195019 is a binary star system in the northern constellation of Delphinus. The brighter star has a close orbiting exoplanet companion. This system is located at a distance of 122  light years from the Sun based on parallax measurements, [1] but it is drifting closer with a radial velocity of −91.3 km/s. [6] Although it has an absolute magnitude of 4.01, [5] at that distance the system is considered too faint to be viewed with the naked eye, having a combined apparent visual magnitude of 6.87. [5] However, it should be readily visible with a pair of binoculars or a small telescope. [13]

The spectrum of the primary member, designated component A, presents as a G-type main-sequence star with a stellar classification of G1V. [3] An older stellar classification of G3 V/IV [14] suggested it may be near the end of its main sequence lifespan and is evolving into a subgiant star. [13] This is an older star with an estimated age of nearly 8 [8] billion years and a low level of magnetic activity in its chromosphere. [8] The abundance of iron is near solar. [9] The star has a mass similar to the Sun but a larger radius. It is radiating 2.23 times the luminosity of the Sun from its photosphere at an effective temperature of 5,825 K. [8]

The co-moving companion, component B, was first reported by G. W. Hough in 1881. As of 2016, it is located at an angular separation of 3.40 ″ along a position angle of 334° relative to the primary. [2] This corresponds to a projected separation of 131  AU. This is a K-type star with 70% of the mass of the Sun [10] and is magnitude 10.60. [2]

Planetary system

In 1998, a planet was discovered at Lick Observatory utilizing a radial velocity method, orbiting around Star HD 195019 A. [14] A search of astrometric observations from Hipparcos suggested this may be a stellar object in a near polar orbit. [15] [16] [13] However, interferometric observations ruled out a stellar companion in this orbit with high likelihood. [17]

The HD 195019 planetary system [9]
Companion
(in order from star) 		Mass Semimajor axis
( AU) 		Orbital period
( days) 		Eccentricity Inclination Radius
b >3.69 ± 0.30  MJ 0.1388 ± 0.0080 18.20132 ± 0.00039 0.0138 ± 0.0044 — —

See also

References

  1. ^ a b c d e 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.
  2. ^ a b c Mason, Brian D.; et al. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode: 2001AJ....122.3466M. doi: 10.1086/323920. ISSN  0004-6256. S2CID  119533755.
  3. ^ a b Gray, R. O.; et al. (April 2001). "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars". The Astronomical Journal. 121 (4): 2148–2158. Bibcode: 2001AJ....121.2148G. doi: 10.1086/319956. ISSN  0004-6256. S2CID  117076031.
  4. ^ Bidelman, W. P. (October 1985). "G. P. Kuiper's spectral classifications of proper-motion stars". Astrophysical Journal Supplement Series. 59: 197–227. Bibcode: 1985ApJS...59..197B. doi: 10.1086/191069.
  5. ^ a b c d 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.
  6. ^ a b 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.
  7. ^ Takeda, Yoichi (February 2005). "Precise Differential Analysis of Stellar Metallicities: Application to Solar Analogs Including 16 Cyg A and B". Publications of the Astronomical Society of Japan. 57 (1): 83–96. Bibcode: 2005PASJ...57...83T. doi: 10.1093/pasj/57.1.83.
  8. ^ a b c d e f g h i Bonfanti, A.; et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv: 1511.01744. Bibcode: 2016A&A...585A...5B. doi: 10.1051/0004-6361/201527297. S2CID  53971692. A5.
  9. ^ a b c d Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv: astro-ph/0607493. Bibcode: 2006ApJ...646..505B. doi: 10.1086/504701. S2CID  119067572.
  10. ^ a b Quarles, Billy; et al. (2020). "Orbital stability of circumstellar planets in binary systems". The Astronomical Journal. 159 (3): 80. arXiv: 1912.11019. Bibcode: 2020AJ....159...80Q. doi: 10.3847/1538-3881/ab64fa. S2CID  209444271.
  11. ^ a b c Rice, Malena; Brewer, John M. (August 2020). "Stellar Characterization of Keck HIRES Spectra with The Cannon". The Astrophysical Journal. 898 (2): 119. arXiv: 2007.02942. Bibcode: 2020ApJ...898..119R. doi: 10.3847/1538-4357/ab9f96. 119.
  12. ^ "HD 195019". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-01-03.
  13. ^ a b c Kaler, James. "HD 195019 Delphini". The Planet Project. Retrieved 2024-01-03.
  14. ^ a b Fischer, Debra A.; et al. (1999). "Planetary Companions around Two Solar-Type Stars: HD 195019 and HD 217107". Publications of the Astronomical Society of the Pacific. 111 (755): 50–56. arXiv: astro-ph/9810420. Bibcode: 1999PASP..111...50F. doi: 10.1086/316304. S2CID  17980987.
  15. ^ Han, Inwoo; et al. (February 2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal. 548 (1): L57–L60. Bibcode: 2001ApJ...548L..57H. doi: 10.1086/318927. S2CID  120952927.
  16. ^ Sahlmann, J.; et al. (April 2011). "HD 5388 b is a 69 MJup companion instead of a planet". Astronomy & Astrophysics. 528: L8. arXiv: 1102.3372. Bibcode: 2011A&A...528L...8S. doi: 10.1051/0004-6361/201116533. S2CID  55566004. L8.
  17. ^ Koresko, C. D.; et al. (December 2002). "Long baseline interferometric observations of HD 195019: no K dwarf companion detected". Bulletin of the American Astronomical Society. 34: 1177. Bibcode: 2002AAS...201.4613K.


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