Astronomy:HD 195019

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Short description: Binary star in the constellation Delphinus
HD 195019
Observation data
Equinox J2000.0]] (ICRS)
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)[1] mas/yr
Dec.: −56.618(19)[1] mas/yr
Parallax (π)26.6465 ± 0.0225[1] mas
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, 2MASS J20281860+1846103[12]
Database references
SIMBADdata

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 astronomical unit|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. ↑ 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. ↑ 2.0 2.1 2.2 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. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M. 
  3. ↑ 3.0 3.1 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. doi:10.1086/319956. ISSN 0004-6256. Bibcode: 2001AJ....121.2148G. 
  4. ↑ Bidelman, W. P. (October 1985). "G. P. Kuiper's spectral classifications of proper-motion stars". Astrophysical Journal, Supplement Series 59: 197–227. doi:10.1086/191069. Bibcode: 1985ApJS...59..197B. 
  5. ↑ 5.0 5.1 5.2 5.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  6. ↑ 6.0 6.1 Soubiran, C. et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics 616: A7. doi:10.1051/0004-6361/201832795. Bibcode: 2018A&A...616A...7S. 
  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. doi:10.1093/pasj/57.1.83. Bibcode: 2005PASJ...57...83T. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 Bonfanti, A. et al. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics 585: 14. doi:10.1051/0004-6361/201527297. A5. Bibcode: 2016A&A...585A...5B. 
  9. ↑ 9.0 9.1 9.2 9.3 Butler, R. P. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. doi:10.1086/504701. Bibcode: 2006ApJ...646..505B. 
  10. ↑ 10.0 10.1 Quarles, Billy et al. (2020). "Orbital stability of circumstellar planets in binary systems". The Astronomical Journal 159 (3): 80. doi:10.3847/1538-3881/ab64fa. Bibcode: 2020AJ....159...80Q. 
  11. ↑ 11.0 11.1 11.2 Rice, Malena; Brewer, John M. (August 2020). "Stellar Characterization of Keck HIRES Spectra with The Cannon". The Astrophysical Journal 898 (2): 119. doi:10.3847/1538-4357/ab9f96. 119. Bibcode: 2020ApJ...898..119R. 
  12. ↑ "HD 195019". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+195019. 
  13. ↑ 13.0 13.1 13.2 "HD 195019 Delphini". The Planet Project. http://stars.astro.illinois.edu/sow/hd195019.html. 
  14. ↑ 14.0 14.1 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. doi:10.1086/316304. Bibcode: 1999PASP..111...50F. 
  15. ↑ Han, Inwoo et al. (February 2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal 548 (1): L57–L60. doi:10.1086/318927. Bibcode: 2001ApJ...548L..57H. 
  16. ↑ Sahlmann, J. et al. (April 2011). "HD 5388 b is a 69 MJup companion instead of a planet". Astronomy & Astrophysics 528: L8. doi:10.1051/0004-6361/201116533. L8. Bibcode: 2011A&A...528L...8S. 
  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. 

Coordinates: Sky map 20h 28m 18.6363s, +18° 46′ 10.188″



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