Astronomy:HD 220689

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Short description: Star in the constellation Aquarius
HD 220689
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  23h 25m 52.99170s[1]
Declination –20° 36′ 57.6998″[1]
Apparent magnitude (V) +7.74[2]
Characteristics
Spectral type G3V[3]
B−V color index +0.603±0.002[2]
Astrometry
Radial velocity (Rv)+12.30±0.14[1] km/s
Proper motion (μ) RA: –15.328[1] mas/yr
Dec.: –177.593[1] mas/yr
Parallax (π)21.3074 ± 0.0236[1] mas
Distance153.1 ± 0.2 ly
(46.93 ± 0.05 pc)
Absolute magnitude (MV)4.50[2]
Details[4]
Mass1.016±0.048 M
Radius1.068±0.047 R
Luminosity1.491±0.005[5] L
Surface gravity (log g)4.360±0.045 cgs
Temperature5,921±26 K
Metallicity [Fe/H]−0.07±0.10 dex
Rotation~29 d
Rotational velocity (v sin i)5.5[6] km/s
Age4.586±2.487 Gyr
Other designations
BD–21°6419, GC 32591, HD 220689, HIP 115662, SAO 191898, G 273-43[7]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia
data

HD 220689 is a single[8] star in the equatorial constellation of Aquarius. It is a challenge to view with the naked eye, having an apparent visual magnitude of +7.74,[2] but is readily viewed with a pair of binoculars.[9] The star is located at a distance of 153 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +12 km/s.[1] A survey in 2015 has ruled out the existence of any additional stellar companions at projected distances from 26 to 305 astronomical units.[8]

The stellar classification of HD 220689 is G3V,[3] matching a yellow hued G-type main-sequence star that is generating energy through core hydrogen fusion. It is roughly 4.6 billion years old and is spinning with a projected rotational velocity of 5.5 km/s,[6] giving it a rotation period of around 29 days.[4] The star has a similar size, mass, and elemental abundances as the Sun. It is radiating 1.5[5] times the luminosity of the Sun from its photosphere at an effective temperature of 5,921 K.[4]

Planetary system

From 1998 to 2012, the star was under observation from the CORALIE echelle spectrograph at La Silla Observatory. In 2012, a long-period, wide-orbiting exoplanet was deduced from radial velocity variations. This was published in November.[10] The maximum orbital period allowing for dynamic stability of a hypothetical inner planet is 3.9 years.[4] In 2023, the inclination and true mass of HD 220689 b were determined via astrometry.[11]

The HD 220689 planetary system[11]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(years)
Eccentricity Inclination Radius
b 1.2+0.22
−0.11
 MJ
3.433+0.065
−0.064
6.23+0.15
−0.14
0.053+0.06
−0.037
71+13
−18
or 109+18
−13
°

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 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.
  2. 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode2012AstL...38..331A. 
  3. 3.0 3.1 Houk, Nancy; Smith-Moore, M. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. 4. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode1988mcts.book.....H. 
  4. 4.0 4.1 4.2 4.3 Barbato, D. et al. (August 2018). "Exploring the realm of scaled solar system analogues with HARPS". Astronomy & Astrophysics 615: 21. doi:10.1051/0004-6361/201832791. A175. Bibcode2018A&A...615A.175B. 
  5. 5.0 5.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  6. 6.0 6.1 Luck, R. Earle (March 2018). "Abundances in the Local Region. III. Southern F, G, and K Dwarfs". The Astronomical Journal 155 (3): 31. doi:10.3847/1538-3881/aaa9b5. 111. Bibcode2018AJ....155..111L. 
  7. "HD 220689". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+220689. 
  8. 8.0 8.1 Mugrauer, M.; Ginski, C. (12 May 2015). "High-contrast imaging search for stellar and substellar companions of exoplanet host stars". Monthly Notices of the Royal Astronomical Society 450 (3): 3127–3136. doi:10.1093/mnras/stv771. Bibcode2015MNRAS.450.3127M. https://academic.oup.com/mnras/article/450/3/3127/1063872. Retrieved 19 June 2020. 
  9. "The astronomical magnitude scale". International Comet Quarterly. http://www.icq.eps.harvard.edu/MagScale.html. 
  10. Marmier, M. et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics 551: A90. doi:10.1051/0004-6361/201219639. Bibcode2013A&A...551A..90M. 
  11. 11.0 11.1 Xiao, Guang-Yao et al. (March 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. 

External links