Zosma, Delta Leonis, is another rapid rotator in Leo, with a projected rotational velocity of 180 km/s. Like Regulus and Denebola, Zosma has an equatorial bulge and an oblate shape.
Zosma is a white main sequence star of the spectral type A4 V, approximately 58.4 light years from Earth. It has a visual magnitude of 2.56.
Delta Leonis is slightly larger and hotter than the Sun. It has 214% of the solar radius and is about 15 times more luminous than the Sun. In about 600 million years, it will become a red giant.
The star is suspected to be a member of the Ursa Major Moving Group, a group of stars that includes most of the brightest stars in Ursa Major that share a common origin and motion through space.
The star’s traditional name, Zosma, comes from ancient Greek and means “the girdle.” Zosma is located on the lion’s hip.
Gamma Leonis is a double star in Leo. Its traditional name, Algieba or Al Gieba, comes from the Arabic Al-Jabhah, which means “the forehead.” The star is sometimes also known by its Latin name, Juba.
Algieba is composed of a giant star with the spectral classification K1-IIIbCN0.5 and a dimmer companion star which belongs to the spectral class G7IIICN-I. The brighter giant is 180 times more luminous than the Sun and has an apparent magnitude of 2.28. The G7 class star has a visual magnitude of 3.51, is 50 times brighter than the Sun, and has 10 times the solar diameter. The two stars have an orbital period of 500 years. A planet was discovered in the orbit of the primary star in November 2009.
The Gamma Leonis system has a combined apparent magnitude of 1.98 and is approximately 130 light years distant from the Sun. It is easy to observe in a small telescope under good conditions and appears as a bright double star with orange red and greenish yellow components.
Regulus, Alpha Leonis, is the brightest star in Leo and the 22nd brightest star in the sky. It has an apparent magnitude of 1.35 and is approximately 77 light years distant.
Regulus is a four-star system composed of two pairs of stars. Regulus A is a spectroscopic binary star composed of a blue-white main sequence star belonging to the spectral class B7 V, and a companion star which cannot be resolved, but is believed to be a white dwarf. The two stars complete an orbit around their common centre of mass every 40 days or so.
Regulus B and Regulus C share a common proper motion. They are located at an angular distance of 177 arc seconds from Regulus A. They are dimmer main sequence stars with an apparent magnitude of 8.14 and 13.5. Regulus B is a K2V star and the companion is believed to belong to the spectral class M4V. The two stars are separated by about 100 astronomical units and have an orbital period of 2,000 years.
Denebola is the second brightest star in Leo and the 61st brightest star in the sky. It is a main sequence star with the stellar classification A3 V. It has an apparent magnitude of 2.113 and is approximately 35.9 light years distant from Earth. The star can easily be seen without binoculars.
Denebola has 75% more mass than the Sun, 173% of the solar radius, and is 12 times more luminous. It is classified as a Delta Scuti variable, which means that its brightness varies slightly over a period of a few hours. Denebola exhibits variations in luminosity of 0.025 magnitudes about ten times a day.
Beta Leonis is a relatively young star. Its estimated age is less than 400 million years. Like Regulus, Denebola is a rapid rotator, which results in an oblate shape of the star, with a bulge at the equator. The star’s projected rotational velocity is 128 km/s.
Theta Leonis is another white main sequence star. It has the stellar classification A2 V and a mass 2.5 times that of the Sun. The star is visible to the naked eye. It has an apparent magnitude of 3.324 and is approximately 165 light years distant from the solar system.
Theta Leonis has an estimated age of 550 million years, which means that it is much younger than the Sun. It exhibits an excess emission of infrared, which indicates the presence of a circumstellar disk of dust. The star has a relatively high projected rotational velocity, 23 km/s.
The star is sometimes known by its traditional names Chort (from the Arabic al-kharāt or al-khurt, which means “small rib”), Coxa (Latin for “hip”) and Chertan (from the Arabic al-kharātān, meaning “two small ribs”).
Zeta Leonis is a giant star belonging to the spectral class F0 III. Its traditional name, Adhafera, comes from the Arabic al-ðafīrah, which means “the curl” or “the braid.”
Zeta Leonis has a visual magnitude of 3.33 and is about 274 light years distant from the solar system. It is 85 times more luminous than the Sun.
The star has an optical companion, 35 Leonis, which has an apparent magnitude of 5.90. 35 Leonis is located 325.9 arc seconds away from Adhafera and it is only a line-of-sight companion, as it is only 100 light years distant from Earth.