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]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| 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 mas/yr[1] Dec.: –177.593 mas/yr[1] |
| Parallax (π) | 21.3074 ± 0.0236 mas[1] |
| Distance | 153.1 ± 0.2 ly (46.93 ± 0.05 pc) |
| Absolute magnitude (MV) | 4.50[2] |
| Details[4] | |
| Mass | 1.016±0.048 M☉ |
| Radius | 1.068±0.047 R☉ |
| Luminosity | 1.491±0.005[5] L☉ |
| Surface gravity (log g) | 4.360±0.045 cgs |
| Temperature | 5,921±26 K |
| Metallicity [Fe/H] | −0.07±0.10 dex |
| Rotation | ~29 d |
| Rotational velocity (v sin i) | 5.5[6] km/s |
| Age | 4.586±2.487 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
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
editFrom 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]
| 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
edit- ^ a b c d e f 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.
- ^ 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.
- ^ a b Houk, Nancy; Smith-Moore, M. (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 4. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1988mcts.book.....H.
- ^ a b c d Barbato, D.; et al. (August 2018). "Exploring the realm of scaled solar system analogues with HARPS". Astronomy & Astrophysics. 615: 21. arXiv:1804.08329. Bibcode:2018A&A...615A.175B. doi:10.1051/0004-6361/201832791. S2CID 119099721. A175.
- ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b Luck, R. Earle (March 2018). "Abundances in the Local Region. III. Southern F, G, and K Dwarfs". The Astronomical Journal. 155 (3): 31. Bibcode:2018AJ....155..111L. doi:10.3847/1538-3881/aaa9b5. S2CID 125765376. 111.
- ^ "HD 220689". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-02.
- ^ a b 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. Bibcode:2015MNRAS.450.3127M. doi:10.1093/mnras/stv771. hdl:1887/49340. Retrieved 19 June 2020.
- ^ "The astronomical magnitude scale". International Comet Quarterly. Retrieved 2020-12-31.
- ^ 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. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
- ^ a b Xiao, Guang-Yao; Liu, Yu-Juan; et al. (March 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. arXiv:2303.12409.
External links
edit- "HD 220689 b". Extrasolar Planets Encyclopaedia. Retrieved 2021-01-02.