54 Leonis
Star in the constellation Leo
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54 Leonis is a binary star[13] system in the zodiac constellation of Leo, located around 321[3] light years from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 4.30.[14] As of 2017, the pair had an angular separation of 6.60″ along a position angle of 113°.[15] They have a physical separation of around 533 AU (79,700 Gm).[11]
 | |
| Observation data Epoch J2000.0 Equinox | |
|---|---|
| Constellation | Leo |
| 54 Leo A | |
| Right ascension | 10h 55m 36.80266s[1] |
| Declination | +24° 44′ 59.0440″[1] |
| Apparent magnitude (V) | 4.477[2] |
| 54 Leo B | |
| Right ascension | 10h 55m 37.24836s[3] |
| Declination | +24° 44′ 56.5478″[3] |
| Apparent magnitude (V) | 6.29[4] |
| Characteristics | |
| 54 Leo A | |
| Spectral type | A0 V[5] |
| B−V color index | +0.001[5] |
| 54 Leo B | |
| Spectral type | A2 Vn[5] |
| B−V color index | +0.07[4] |
| Astrometry | |
| 54 Leo A | |
| Radial velocity (Rv) | −0.49±0.98[6] km/s |
| Proper motion (μ) | RA: −78.057[1] mas/yr Dec.: −16.520[1] mas/yr |
| Parallax (π) | 9.8275±0.3537 mas[1] |
| Distance | 330 ± 10 ly (102 ± 4 pc) |
| Absolute magnitude (MV) | –0.29[7] |
| 54 Leo B | |
| Radial velocity (Rv) | 1.30±0.92[6] km/s |
| Proper motion (μ) | RA: −75.374[3] mas/yr Dec.: −18.595[3] mas/yr |
| Parallax (π) | 10.1748±0.0569 mas[3] |
| Distance | 321 ± 2 ly (98.3 ± 0.5 pc) |
| Details | |
| 54 Leo A | |
| Mass | 2.37[8] M☉ |
| Radius | 4.9[8] R☉ |
| Luminosity | 163[8] L☉ |
| Surface gravity (log g) | 3.43[8] cgs |
| Temperature | 9,337[8] K |
| Rotational velocity (v sin i) | 185[9] km/s |
| Age | 411+137 −168[10] Myr |
| 54 Leo B | |
| Mass | 2.23[8] M☉ |
| Radius | 2.02[8] R☉ |
| Luminosity | 22.8[8] L☉ |
| Surface gravity (log g) | 4.17[8] cgs |
| Temperature | 8,868[8] K |
| Rotational velocity (v sin i) | 250±20[11] km/s |
| Other designations | |
| 54 Leo, BD+25 2314, CCDM J10556+2445, HIP 53417, Struve 1487[12] | |
| 54 Leo A: HD 94601, HR 4259, SAO 81583 | |
| 54 Leo B: HD 94602, HR 4260, SAO 81584 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
The magnitude 4.477[2] primary, designated component A, is an A-type main-sequence star with a stellar classification of A0 V,[5] which indicates it is generating energy through hydrogen fusion at its core. It has a high rate of spin, showing a projected rotational velocity of 185 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 8% larger than the polar radius.[9] The star is roughly 411 million years old[10] with 2.4 times the mass of the Sun and about 4.9 times the Sun's radius.[8]
The fainter magnitude 6.29[4] secondary, component B, is a smaller A-type main-sequence star with a class of A2 Vn.[5] The 'n' suffix indicates wide "nebulous" lines due to rapid rotation. It is spinning with an even higher projected rotational velocity of 250 km/s.[11] The star has about twice the Sun's radius.[8]
Asteroid 729 Watsonia occulted HIP 53417 on March 3, 2013 at 01:48.[16]