Star in the constellation Crater
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]
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
From 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 M J , somewhat higher than its minimum mass deduced from radial velocity measurements.[ 4] [ 7]
References
^ 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 .