HD 220773 is a star in the northern constellation of Pegasus. It has an apparent visual magnitude of 7.10,[1] which is too faint to be visible with the naked eye. The distance to this system, as determined by parallax measurements, is 165 light years,[2] but it is drifting closer with a radial velocity of −37.7 km/s.[5] The star shows a high proper motion, traversing the celestial sphere at an angular rate of 0.187 arcsec yr−1.[10]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pegasus[1] |
| Right ascension | 23h 26m 27.445s[2] |
| Declination | +08° 38′ 37.84″[2] |
| Apparent magnitude (V) | 7.10[1] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | G0 V[3] or F9 V[4] |
| B−V color index | 0.602±0.005[1] |
| Astrometry | |
| Radial velocity (Rv) | −37.735±0.0009[5] km/s |
| Proper motion (μ) | RA: 27.096 mas/yr[2] Dec.: −222.458 mas/yr[2] |
| Parallax (π) | 19.7694 ± 0.0669 mas[2] |
| Distance | 165.0 ± 0.6 ly (50.6 ± 0.2 pc) |
| Absolute magnitude (MV) | 3.57[1] |
| Details | |
| Mass | 1.154±0.003[6] M☉ |
| Radius | 1.73±0.02[6] R☉ |
| Luminosity | 3.16±0.01[6] L☉ |
| Surface gravity (log g) | 4.02±0.01[6] cgs |
| Temperature | 5,852±26[6] K |
| Metallicity [Fe/H] | 0.09±0.06[7] dex |
| Rotational velocity (v sin i) | 3.82±1.00[8] km/s |
| Age | 6.3±0.1[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of HD 220773 presents as a late type star F-type or early G-type main-sequence star with a stellar classification of F9 V[4] or G0 V,[3] respectively. It is older than the Sun, with an estimated age of 6.3 billion years,[6] and the magnetic activity in the chromosphere is at a low level.[7] The star has 15% greater mass than the Sun but the radius is 73% larger.[6] The abundance of iron, a measure of the star's metallicity, is slightly higher than solar.[7] It is radiating over three times the luminosity of the Sun from its photosphere at an effective temperature of 5,852 K.[6]
A survey in 2015 ruled out the existence of any additional stellar companions at projected distances from 31 to 337 astronomical units.[3]
Search for planets
editThe detection of an exoplanet, HD 220773 b, by the radial velocity method was claimed in 2012 based on observations at the McDonald Observatory. As the inclination of the orbital plane is unknown, only a lower bound on the mass can be determined. This object has at least 1.45 times the mass of Jupiter. It has a very eccentric orbit with a semimajor axis of around 5 AU, taking 10.2 years to complete an orbit.[7]
However, a follow-up study in 2024 found no evidence of this planet in radial velocity data from the HARPS-N spectrograph. In addition, astrometric data from the Gaia space telescope also shows no evidence of a companion, placing an upper limit on the mass of any planet at 5 AU consistent with the claimed minimum mass of planet b. The McDonald team stated that their data collected since 2012 is also no longer consistent with the claimed planet.[11]
References
edit- ^ a b c d e 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 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.
- ^ a b c 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.
- ^ a b Wittrock, Justin M.; et al. (2017). "Exclusion of Stellar Companions to Exoplanet Host Stars". The Astronomical Journal. 154 (5): 184. arXiv:1709.05315. Bibcode:2017AJ....154..184W. doi:10.3847/1538-3881/aa8d69. S2CID 55789971.
- ^ 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.
- ^ 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.
- ^ a b c d Robertson, Paul; et al. (2012). "The McDonald Observatory Planet Search: New Long-period Giant Planets and Two Interacting Jupiters in the HD 155358 System". The Astrophysical Journal. 749 (1): 39. arXiv:1202.0265. Bibcode:2012ApJ...749...39R. doi:10.1088/0004-637X/749/1/39. S2CID 59273311.
- ^ Tejada Arevalo, Roberto A.; et al. (October 2021). "Further Evidence for Tidal Spin-up of Hot Jupiter Host Stars". The Astrophysical Journal. 919 (2): 138. arXiv:2107.05759. Bibcode:2021ApJ...919..138T. doi:10.3847/1538-4357/ac1429. 138.
- ^ "HD 220773". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 September 2020.
- ^ Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
- ^ Carleo, Ilaria; Desidera, Silvano; et al. (June 2024). "Disproving the High-eccentricity Planet HD 220773b". Research Notes of the AAS. 8 (6): 161. doi:10.3847/2515-5172/ad57b5.