)  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Right ascension | 10h 32m 48.67168s[1] |
| Declination | +09° 18′ 23.7094″[1] |
| Apparent magnitude (V) | 3.83 - 3.90[2] |
| Characteristics | |
| Spectral type | B1 Iab[3] |
| U−B color index | –0.945[4] |
| B−V color index | –0.153[4] |
| Variable type | α Cyg[2] |
| Astrometry | |
| Radial velocity (Rv) | +42.0[5] km/s |
| Proper motion (μ) | RA: –5.93 ± 0.20[1] mas/yr Dec.: –3.40 ± 0.11[1] mas/yr |
| Parallax (π) | 0.60 ± 0.18[1] mas |
| Distance | approx. 5,000 ly (approx. 1,700 pc) |
| Absolute magnitude (MV) | –6.8[6] |
| Details | |
| Mass | 27.1 ± 8.4[7] M☉ |
| Radius | 37.4[8] R☉ |
| Luminosity | 295,000[6] L☉ |
| Surface gravity (log g) | 3.09[9] cgs |
| Temperature | 24,200[9] K |
| Metallicity [Fe/H] | –0.89[9] dex |
| Rotation | 7 ± 2 days[10] |
| Rotational velocity (v sin i) | 60[11] km/s |
| Age | 4.5 ± 0.1[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Rho Leonis (ρ Leo) is a binary star in the zodiac constellation of Leo, and, like the prominent nearby star Regulus, is near the ecliptic. With an apparent visual magnitude of 3.9,[4] this star can be readily seen with the naked eye. Parallax measurements give a distance estimate of about 5,400 light-years (1,700 parsecs) from the Earth.[12]
This is an enormous star with about 21 times the Sun's mass (M☉)[13] and 37 times the Sun's radius.[8] Its spectrum matches a stellar classification of B1 Iab,[3] with the 'Iab' luminosity class indicating that it is in the supergiant stage of its evolution. Rho Leonis is radiating about 295,000 times the Sun's luminosity[6] at an effective temperature of 24,200 K,[9] giving it the blue-white hue typical of a B-type star. A strong stellar wind is expelling mass from the outer envelope at a rate of 3.5 × 10−7 M☉ per year, or the equivalent of 1 M☉ every 2.8 million years.[8] The rotation rate is probably about once per 7 days, with an upper limit of 47 days.[10]
Rho Leonis is classified as a runaway star, which means it has a peculiar velocity of at least 30 km s−1 relative to the surrounding stars. It has radial velocity of 42 km s−1 away from the Sun and a proper motion that is carrying it about 1.56 Astronomical Units per year, equivalent to 7 km s−1,[14] in a transverse direction. The star is situated about 2,300 light-years (710 parsecs) above the galactic plane.[15]
Rho Leo is 0.15 degree north of the ecliptic, so it can be occulted by the moon. Unusual light variation during these occultations has been explained as the result of a possible close companion. The companion would be just over one magnitude fainter and separated by 0.01 arcsec.[16] The companion has not been detected by any other means although it should be easily detected with modern observations.[17]
References
- ^ a b c d e van Leeuwen, F. (November 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
- ^ a b 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. Bibcode:2009yCat....102025S.
- ^ a b Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179
- ^ a b c Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publ. Dept. Astron. Univ. Chile, 1: 1–17, Bibcode:1966PDAUC...1....1G
- ^ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Washington, Bibcode:1953GCRV..C......0W
- ^ a b c Crowther, P. A.; Lennon, D. J.; Walborn, N. R. (January 2006), "Physical parameters and wind properties of galactic early B supergiants", Astronomy and Astrophysics, 446 (1): 279–293, arXiv:astro-ph/0509436, Bibcode:2006A&A...446..279C, doi:10.1051/0004-6361:20053685
- ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x
- ^ a b c Kraus, M.; Borges Fernandes, M.; Kubát, J. (May 2009), "Parameters of galactic early B supergiants. The influence of the wind on the interstellar extinction determination", Astronomy and Astrophysics, 499 (1): 291–299, Bibcode:2009A&A...499..291K, doi:10.1051/0004-6361/200810319
- ^ a b c d Gies, Douglas R.; Lambert, David L. (March 10, 1992), "Carbon, nitrogen, and oxygen abundances in early B-type stars", Astrophysical Journal, Part 1, 387: 673–700, Bibcode:1992ApJ...387..673G, doi:10.1086/171116
- ^ a b Kholtygin, A. F.; et al. (November 2007), "Microvariability of line profiles in the spectra of OB stars: III. The supergiant ρ LEO", Astronomy Reports, 51 (11): 920–931, Bibcode:2007ARep...51..920K, CiteSeerX 10.1.1.618.7621, doi:10.1134/S1063772907110054
- ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B
- ^ Perryman, M. A. C.; et al. (July 1997), "The HIPPARCOS Catalogue", Astronomy & Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P
- ^ Conlon, E. S.; et al. (September 1990), "The runaway nature of distant early-type stars in the galactic halo", Astronomy and Astrophysics, 236 (2): 357–361, Bibcode:1990A&A...236..357C
- ^ An Astronomical Unit (AU) is 1.5 × 108 km, while a year is 3.2 × 107 seconds. Thus, 1.56 AU/year = (1.56 AU/yr) × (1.5 × 108 km/AU) / (3.2 × 107 s/yr) = 7 km/s.
- ^ Lauroesch, J. T.; Meyer, David M. (July 2003), "Variable Na I Absorption toward ρ Leonis: Biased Neutral Formation in the Diffuse Interstellar Medium?", The Astrophysical Journal, 591 (2): L123–L126, arXiv:astro-ph/0306005, Bibcode:2003ApJ...591L.123L, doi:10.1086/377164
- ^ Radick, R. R.; Africano, J. L.; Flores, M. R.; Klimke, D. A.; Tyson, E. T. (1982). "Cloudcroft occulation summary. II - April 1980-December 1981". The Astronomical Journal. 87: 1874. Bibcode:1982AJ.....87.1874R. doi:10.1086/113277. ISSN 0004-6256.
- ^ McAlister, H. A. (1978). "Binary stars unresolved by speckle interferometry". Publications of the Astronomical Society of the Pacific. 90: 288. Bibcode:1978PASP...90..288M. doi:10.1086/130327. ISSN 0004-6280.
External links
- Kaler, James B., "Rho Leonis", Stars, University of Illinois, retrieved 2012-01-11