AF Leporis

AF Leporis, also known as HD 35850, is an F-type main-sequence star located 87.5 light-years (26.8 parsecs) away from the Solar System in the constellation of Lepus. With an apparent magnitude of 6.3, it is near the limit of naked eye visibility under ideal conditions. While some studies consider it to be a close spectroscopic binary with a separation of 0.021 AU,[8] other studies show no evidence of binarity, and it is likely that the supposed binarity is an artifact resulting from the presence of starspots.[9][4]

A light curve for AF Leporis, plotted from TESS data[11]
AF Leporis
Location of AF Leporis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Lepus
Right ascension 05h 27m 04.76333s[1]
Declination −11° 54′ 03.4660″[1]
Apparent magnitude (V) 6.26 - 6.35[2]
Characteristics
Evolutionary stage Main sequence
Spectral type F8V(n)k:[3]
Apparent magnitude (B) 6.832±0.015[4]
Apparent magnitude (V) 6.295±0.010[4]
Apparent magnitude (G) 6.209±0.003[1]
Apparent magnitude (J) 5.268±0.027[4]
Apparent magnitude (H) 5.087±0.026[4]
Apparent magnitude (K) 4.926±0.021[4]
Variable type RS CVn[2]
Astrometry
Radial velocity (Rv)21.10±0.37[1] km/s
Proper motion (μ) RA: 16.915 mas/yr[1]
Dec.: −49.318 mas/yr[1]
Parallax (π)37.2539 ± 0.0195 mas[1]
Distance87.55 ± 0.05 ly
(26.84 ± 0.01 pc)
Absolute magnitude (MV)4.14[5]
Details
Mass1.09±0.06[6] M☉
Radius1.25±0.06[7] R☉
Luminosity (bolometric)1.84±0.01[8] L☉
Surface gravity (log g)4.30±0.05[6] cgs
Temperature6130±60[7] K
Metallicity [Fe/H]+0.19±0.02[7] dex
Rotation0.9660±0.0023 d[9]
Rotational velocity (v sin i)50±5[7] km/s
Age24±3[7] Myr
Other designations
AF Lep, NSV 16310, BD−12 1169, FK5 2409, HD 35850, HIP 25486, HR 1817, SAO 150461, PPM 215789, TIC 94945758, TYC 5340-1141-1, GCRV 3284, GSC 05340-01141, IRAS 05247-1156[10]
Database references
SIMBADdata

AF Leporis is a member of the Beta Pictoris moving group, with an astronomically young age of about 24 million years. It hosts a circumstellar disk and one known exoplanet.[7]

Planetary system

In 2023, a gas giant exoplanet was discovered in orbit around AF Leporis by direct imaging using the NIRC2 instrument at the W. M. Keck Observatory and the SPHERE instrument at the Very Large Telescope. It was also detected in astrometric data from the Hipparcos and Gaia spacecraft, allowing an accurate measurement of its mass.[7][4][12] Spectroscopic evidence suggests that AF Leporis b has a metal-rich atmosphere with silicate clouds.[6]

There have been multiple studies of AF Leporis b, which have found somewhat different parameters. One study finds a dynamical mass of 3.2+0.7
−0.6 MJ, somewhat lower than the predicted mass based on imaging,[7] while another study instead finds 5.5 MJ, consistent with photometric mass estimates.[4] The former study finds an orbital inclination of 50°+9°
−12°, consistent with the stellar inclination of 54°+11°
−9° and suggesting an aligned system,[7] while the latter study instead finds an inclination of 82°+22°
−23°.[4] All studies have found that the planet has a fairly eccentric orbit.

Two images of AF Lep b with the SPHERE instrument on the Very Large Telescope[13]
The AF Leporis planetary system[6]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(years)		 Eccentricity Inclination Radius
b 2.8+0.6
−0.5 MJ		 8.2+1.3
−1.7		 22.3+5.6
−6.7		 0.4+0.3
−0.2		 55+8
−13°		 1.2-1.55 RJ
Debris disk 46±9[14] AU — —

See also

References
  1. 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.
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. Gray, R. O.; Corbally, C. J.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 250741593.
  4. Mesa, D.; Gratton, R.; et al. (February 2023). "AF Lep b: the lowest mass planet detected coupling astrometric and direct imaging data". Astronomy & Astrophysics. 672: A93. arXiv:2302.06213. Bibcode:2023A&A...672A..93M. doi:10.1051/0004-6361/202345865. S2CID 256827302.
  5. 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.
  6. Zhang, Zhoujian; Mollière, Paul; et al. (September 2023). "ELemental abundances of Planets and brown dwarfs Imaged around Stars (ELPIS): I. Potential Metal Enrichment of the Exoplanet AF Lep b and a Novel Retrieval Approach for Cloudy Self-luminous Atmospheres". The Astronomical Journal. arXiv:2309.02488.
  7. Franson, Kyle; Bowler, Brendan P.; et al. (February 2023). "Astrometric Accelerations as Dynamical Beacons: A Giant Planet Imaged Inside the Debris Disk of the Young Star AF Lep". The Astrophysical Journal Letters. 950 (2): L19. arXiv:2302.05420. Bibcode:2023ApJ...950L..19F. doi:10.3847/2041-8213/acd6f6.
  8. Pawellek, Nicole; Wyatt, Mark; et al. (April 2021). "A ~75 per cent occurrence rate of debris discs around F stars in the β Pic moving group". Monthly Notices of the Royal Astronomical Society. 502 (4): 5390–5416. arXiv:2101.12049. Bibcode:2021MNRAS.502.5390P. doi:10.1093/mnras/stab269.
  9. Järvinen, S. P.; Arlt, R.; et al. (February 2015). "Doppler images and the underlying dynamo. The case of AF Leporis". Astronomy & Astrophysics. 574: A25. arXiv:1412.2892. Bibcode:2015A&A...574A..25J. doi:10.1051/0004-6361/201424229. S2CID 119205096.
  10. "V* AF Lep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 February 2023.
  11. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  12. De Rosa, Robert J.; Nielsen, Eric L.; et al. (February 2023). "Direct imaging discovery of a super-Jovian around the young Sun-like star AF Leporis". Astronomy & Astrophysics. 672: A94. arXiv:2302.06332. Bibcode:2023A&A...672A..94D. doi:10.1051/0004-6361/202345877.
  13. "Spotting a hidden exoplanet". ESO. 20 February 2023.
  14. Pearce, Tim D.; Launhardt, Ralf; et al. (March 2022). "Planet populations inferred from debris discs. Insights from 178 debris systems in the ISPY, LEECH, and LIStEN planet-hunting surveys". Astronomy & Astrophysics. 659: A135. arXiv:2201.08369. Bibcode:2022A&A...659A.135P. doi:10.1051/0004-6361/202142720. S2CID 246063879.
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