HD 98649 is a star with an orbiting exoplanet in the southern Crater constellation. Based on parallax measurements, it is located at a distance of 137.5 light years from the Sun. The system is drifting further away with a heliocentric radial velocity of 4.3 km/s.[1] With an apparent visual magnitude of +8.00,[2] it is too faint to be viewed with the naked eye. The system has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.24″·yr−1.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Crater |
| Right ascension | 11h 20m 51.76855s[1] |
| Declination | −23° 13′ 02.4295″[1] |
| Apparent magnitude (V) | +8.00[2] |
| Characteristics | |
| Spectral type | G3/5V[3] |
| B−V color index | +0.658[3] |
| Astrometry | |
| Radial velocity (Rv) | 4.25±0.12[1] km/s |
| Proper motion (μ) | RA: −199.735±0.022 mas/yr[1] Dec.: −177.620±0.017 mas/yr[1] |
| Parallax (π) | 23.7206 ± 0.0216 mas[1] |
| Distance | 137.5 ± 0.1 ly (42.16 ± 0.04 pc) |
| Absolute magnitude (MV) | +4.91[2] |
| Details | |
| Mass | 0.97±0.02[4] M☉ |
| Radius | 1.01±0.02[3] R☉ |
| Luminosity (bolometric) | 0.968±0.019[4] L☉ |
| Luminosity (visual, LV) | 0.98±0.003[3] L☉ |
| Surface gravity (log g) | 4.38±0.08[2] cgs |
| Temperature | 5,759±35[2] K |
| Metallicity [Fe/H] | 0.05±0.04[3] dex |
| Rotation | 27±4.0 days[2] |
| Rotational velocity (v sin i) | 1.19[2] km/s |
| Age | 4.44+0.68 −0.58[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
The spectrum of HD 98649 presents as an ordinary G-type main-sequence star with a stellar classification of G3/5V.[3] It is around 4.4[4] billion years old and is spinning slowly with a rotation period of roughly 27 days.[2] The star is similar to the Sun, having nearly the same size, mass, and luminosity. It is considered a solar analog.[4] The level of magnetic activity in the chromosphere is minimal.[2]
Planetary system
editFrom 1998 to 2012, the star was under observance from the CORALIE echelle spectrograph at La Silla Observatory. In 2012, a long-period, wide-orbiting exoplanet was deduced by Doppler spectroscopy. This was published in November. The discoverers noted, "HD 98649b is in the top five of the most eccentric planetary orbit and the most eccentric planet known with a period larger than 600 days." The reason for this high eccentricity is unknown. The team proposed it as a candidate for direct imaging, once it gets out to 10.4 AU at apoastron, or 250 milliarcseconds of separation as viewed from Earth.[2]
Using astrometry from Gaia, astronomers were able to deduce the true mass of HD 98649 b as 9.7 MJ, somewhat higher than its minimum mass deduced from radial velocity measurements.[4][7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 9.7+2.3 −1.9 MJ |
5.97+0.24 −0.21 |
14.74+0.88 −0.75 |
0.852+0.033 −0.022 |
43.7+13 −8.1° |
— |
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 e f g h i j 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 c d e f Rickman, E. L.; et al. (May 2019). "The CORALIE survey for southern extrasolar planets. XVIII. Three new massive planets and two low-mass brown dwarfs at greater than 5 AU separation". Astronomy & Astrophysics. 625: 16. arXiv:1904.01573. Bibcode:2019A&A...625A..71R. doi:10.1051/0004-6361/201935356. S2CID 91184450. A71.
- ^ a b c d e f g Li, Yiting; Brandt, Timothy D.; Brandt, G. Mirek; Dupuy, Trent J.; Michalik, Daniel; Jensen-Clem, Rebecca; Zeng, Yunlin; Faherty, Jacqueline; Mitra, Elena L. (2021). "Precise Masses and Orbits for Nine Radial-velocity Exoplanets". The Astronomical Journal. 162 (6): 266. arXiv:2109.10422. Bibcode:2021AJ....162..266L. doi:10.3847/1538-3881/ac27ab. S2CID 237592581.
- ^ "HD 98649". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-12-20.
- ^ Luyten, W. J. (June 1995). "NLTT Catalogue (Luyten, 1979)". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
- ^ Feng, Fabo; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.