40 Leonis
  | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Leo[1] |
| Right ascension | 10h 19m 44.16688s[2] |
| Declination | +19° 28′ 15.2943″[2] |
| Apparent magnitude (V) | 4.80[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | F6 IV-V[5][3] |
| U−B color index | +0.01[3] |
| B−V color index | +0.45[3] |
| Astrometry | |
| Radial velocity (Rv) | 5.9±0.1[6] km/s |
| Proper motion (μ) | RA: −231.73[2] mas/yr Dec.: −214.33[2] mas/yr |
| Parallax (π) | 46.80±0.24 mas[2] |
| Distance | 69.7 ± 0.4 ly (21.4 ± 0.1 pc) |
| Absolute magnitude (MV) | 3.13[1] |
| Details[7] | |
| Mass | 1.35±0.06 M☉ |
| Radius | 1.68±0.07 R☉ |
| Luminosity | 4.4±0.9 L☉ |
| Habitable zone inner limit | 1.49[8] AU |
| Habitable zone outer limit | 3.46[8] AU |
| Surface gravity (log g) | 4.11±0.02 cgs |
| Temperature | 6,450±140 K |
| Metallicity [Fe/H] | 0.09±0.03 dex |
| Rotational velocity (v sin i) | 17±2 km/s |
| Age | 2.63±0.21 Gyr |
| Other designations | |
| 40 Leo, BD+20°2466, HD 89449, HIP 50564, HR 4054, SAO 99065[9] | |
| Database references | |
| SIMBAD | data |
40 Leonis is a spectroscopic binary system[10] in the zodiac constellation of Leo. It is faintly visible to the naked eye, having an apparent visual magnitude of 4.80.[3] An annual parallax shift of 46.80 mas, as seen from Earth's orbit, yields a distance estimate of 69.7 light years. It is moving away from the Sun with a radial velocity of 5.9[6] km/s and has a relatively high proper motion, traversing the sky at the rate of 0.315[11] arcseconds per year.
The visible component is an F-type star with a stellar classification of F6 IV-V,[3] which indicates the spectrum shows traits of both a main sequence star and a more evolved subgiant star. It is a suspected Delta Scuti variable[12] and shows a depleted lithium abundance.[10] The star is about 2.6 billion years old with a relatively high rate of spin for its age, showing a projected rotational velocity of about 17 km/s. It has 1.35 times the mass of the Sun and 1.68 times the Sun's radius. 40 Leonis is radiating around 4.4 times the Sun's luminosity from its photosphere at an effective temperature of roughly 6,450 K.[7]
40 Leonis was reported as a single-lined spectroscopic binary in 2003, but with no details regarding the orbit or the companion's nature. An X-ray emission with a luminosity of (1.09±0.38)×1029 erg/s has been detected at the star's position, which may be coming from a short-period, low-mass companion.[10]
There are two common proper motion companions to 40 Leonis, NLTT 23781 and NLTT 23782,[13] with a combined magnitude of 16.48, a spectral class of M5 and a wide angular separation from the primary of 5,230″ (1.453°), corresponding to a projected separation of 110,000 AU (1.7 ly).[10] They form a visual binary with a separation of 5.24" from each other.[13] Later data has shown that the companions are much farther away than the primary and therefore do not form a gravitationally bound system.[14]
40 Leonis presents a significant difference on proper motion measurements taken by the Hipparcos and Gaia spacecraft, suggesting the presence of a giant planet.[8]
See also
[edit]References
[edit]- 1 2 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.
- 1 2 3 4 5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- 1 2 3 4 5 6 Huang, Y.; et al. (2015), "Empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs and giants based on interferometric data", Monthly Notices of the Royal Astronomical Society, 454 (3): 2863, arXiv:1508.06080, Bibcode:2015MNRAS.454.2863H, doi:10.1093/mnras/stv1991.
- ↑ 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.
- ↑ Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID 119417105.
- 1 2 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
- 1 2 Maestro, V.; et al. (2013), "Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties", Monthly Notices of the Royal Astronomical Society, 434 (2): 1321, arXiv:1306.5937, Bibcode:2013MNRAS.434.1321M, doi:10.1093/mnras/stt1092.
- 1 2 3 Painter, Katie E.; Bowler, Brendan P.; Franson, Kyle; Becker, Juliette C.; Burt, Jennifer A. (2025-06-26), "Astrometric Accelerations of Provisional Targets for the Habitable Worlds Observatory", The Astronomical Journal, arXiv:2506.21768.
- ↑ "40 Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-19.
- 1 2 3 4 Makarov, V. V.; et al. (November 2008), "Common Proper Motion Companions to Nearby Stars: Ages and Evolution", The Astrophysical Journal, 687 (1): 566–578, arXiv:0808.3414, Bibcode:2008ApJ...687..566M, doi:10.1086/591638, S2CID 17811620, 566−578.
- ↑ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854, S2CID 2603568.
- ↑ Hauck, B. (March 1971), "Short period variable stars. V. Delta Scuti-type stars in the Geneva system", Astronomy and Astrophysics, 11: 79, Bibcode:1971A&A....11...79H.
- 1 2 Fuhrmann, K.; Chini, R. (2015-08-13), "Multiplicity among F-type stars. II.", The Astrophysical Journal, 809 (1): 107, doi:10.1088/0004-637X/809/1/107, ISSN 1538-4357.
- ↑ Fuhrmann, Klaus; Chini, Rolf (2018-06-01), "Nearby Gaia DR2 Companions", Research Notes of the AAS, 2 (2): 56, Bibcode:2018RNAAS...2...56F, doi:10.3847/2515-5172/aacc72, ISSN 2515-5172.
