Iota Leonis

ι Leonis
Location of ι Leonis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Leo
Right ascension 11h 23m 55.45273s[1]
Declination +10° 31′ 46.2195″[1]
Apparent magnitude (V) 4.00[2]
Characteristics
Spectral type F4 IV[3]
U−B color index +1.420[4]
B−V color index +0.456[4]
Variable type Suspected[5]
Astrometry
Radial velocity (Rv)−10.3[6] km/s
Proper motion (μ) RA: +141.45[1] mas/yr
Dec.: −79.14[1] mas/yr
Parallax (π)41.26 ± 1.16 mas[1]
Distance79 ± 2 ly
(24.2 ± 0.7 pc)
Absolute magnitude (MV)+2.13[7]
Orbit[8]
Primaryι Leo A
Companionι Leo B
Period (P)186 yr
Semi-major axis (a)1.91″
Eccentricity (e)0.53
Inclination (i)128°
Longitude of the node (Ω)235°
Periastron epoch (T)B 1948.8
Argument of periastron (ω)
(secondary)		325°
Details
Mass1.62−1.70[3] M☉
Radius2.1[9] R☉
Luminosity11.5[3] L☉
Surface gravity (log g)3.98[10] cgs
Temperature6,739[10] K
Metallicity [Fe/H]0.06[10] dex
Rotational velocity (v sin i)16[3] km/s
Age1.7[3] Gyr
Other designations
ι Leo, 78 Leonis, Gliese426.1(B:GJ11625)[11],BD+11°2348, HD 99028, HIP 55642, HR 4399, SAO 99587[2]
Database references
SIMBADdata

Iota Leonis, Latinized from ι Leonis, is a triple star system in the constellation Leo. The system is fairly close to the Sun, at only 79 light-years (24.2 parsecs) away, based on its parallax.[1] The system has a combined apparent magnitude of 4.00[2] making it faintly visible to the naked eye. It is moving closer to the Sun with a radial velocity of −10 km/s.[6]

Iota Leonis has a spectral type of F3 IV,[3] matching that of an F-type subgiant star. It is a spectroscopic binary, which means it is a binary star with components that are too close together to be able to resolve individually through a telescope. In this case, light from only the primary star can be detected, and it is considered single-lined.[3]

The third component in the star system is designated Iota Leonis B. It orbits the central pair almost every 200 years, and with its perihelion passage in 1948, the separation between the two is steadily growing.[12] Iota Leonis B has a mass approximately 8% greater than that of the Sun.[12] It is a G-type main-sequence star, like the Sun.[13]

  1. ^ a b c d e f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  3. ^ a b c d e f g Cite error: The named reference apj673_2 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference aass26 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference kukarin81 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference gcsrv was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 1 August 2017. Retrieved 13 May 2017.
  9. ^ Cite error: The named reference aass85_3_1015 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference apj354 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference CNS5 was invoked but never defined (see the help page).
  12. ^ a b Fuhrmann, Klaus (2008). "Nearby stars of the Galactic disc and halo - IV". Monthly Notices of the Royal Astronomical Society. 384 (1): 173–224. Bibcode:2008MNRAS.384..173F. doi:10.1111/j.1365-2966.2007.12671.x.
  13. ^ "BD+11 2348B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 9 May 2017.