Star Constellation Facts: Lepus

Constellation of Lepus
Image Credit: Stellarium

The name “Lepus” derives from the Latin word for “hare”, and although there are no myths associated with this constellation, it is often depicted on old charts as a hare being chased by the dogs of Orion, represented by the nearby constellations of Canis Major and Canis Minor. This northern sky constellation is the 51st largest in the night sky, and can be seen by observers located between +63° and -90° of latitude. The brightest star in Lepus is  Arneb, a yellow-white supergiant found 2,200 light years distant that shines with a visual magnitude of 2.589. No meteor showers are associated with Lepus.

Orion Family of Constellations

Lepus is a member of the Orion family of constellations, together with Canis Major, Canis Minor, Monoceros and Orion. Other constellations bordering Lepus includes Caelum, Columba, and Eridanus.

Notable Stars

– Arneb (Alpha Leporis), the most luminous star in Lepus (2.589 mag), is located about 2,200 light years away, and derives its name from the Arabic word for “the hare”. It is about 129 times bigger than the Sun, 14 times as massive, and around 32,000 times brighter. Arneb is also estimated to be only 13 million years old, which is still considered extremely ancient for a F0 Ib class yellow-white supergiant star. Having almost consumed all its fuel, the star is now heating up as it collapses to end its life in a supernova explosion.

– Nihal (Beta Leporis), the constellation’s second most luminous star, is a yellow giant (G5 II) situated 160 light years from our solar system with a magnitude of 2.84. It is around 240 million years old, and is 16 times bigger than our sun, and 3.5 times more massive. Nihal derives from the Arabic for “quenching their thirst.”

Star Constellation Facts: Lepus

– Epsilon Leporis, the third most luminous star in Lepus, is an orange giant (K4 III) found 213 light years away with an apparent magnitude of 3.166. Epsilon Leporis is estimated to be about 1.7 billion years old, and is 40 times bigger than the Sun, with 1.7 times its mass, and 327 times its brightness.

Other notable stars in Lepus includes the blue subgiant Mu Leporis; the blue subgiants Lambda Leporus and Kappa Leporus; the white dwarf Theta Leporus; the yellow-white dwarf stars Gamma Leporus and Eta Leporus; and the orange subgiant Delta Leporus.

Also of note is Zeta Leporis, located about 70 light years away, that is around 1.46 times more massive than our sun, and 14 times brighter. What makes it special is its classification of A2 IV-V(n), with the (n) indicating that it is a very fast rotator, in this case of 245 kms/s. This is close to the point at which a star’s gravity cannot hold itself together to counteract the centrifugal forces created by its angular velocity, and this star spins so fast that the absorption lines in its spectrum are widened by the Doppler effect to the point where they take on a nebulous appearance. Zeta Leporis is also the only other star known to be surrounded by a massive asteroid belt, which was confirmed to surround the star in 2001. Zeta Leporis has an apparent visual magnitude of 3.524, and is estimated to be only about 230 million years old.

Hind’s Crimson StarWorth mentioning, too, is Hind’s Crimson Star (R Leporis), a carbon star that is arguably the most famous variable star in the entire sky. It is classified as a long-period Mira variable star with two distinct periods of variability; one being a period of 418 to 441 days, and another that spans roughly 40 years. During these periods the star can vary in magnitude from 5.5 to as dim as 11.7. Hind’s Crimson Star is about 1,300 light years away, and when its discoverer, J.R Hind, first observed it, he described it as being like “a drop of blood on a black field.” Apart from its distinctively red color, R Leporis is around 500 times bigger than the Sun, and between 5,000 and 7,000 times brighter. Look for Hind’s Crimson Star close to the border with Eridanus, where it is the reddest star in the sky when it is at its dimmest, which occurs about every 14.5 months.

Notable Deep Sky Objects

Lepus contains only one Messier object, the globular cluster M79 (NGC 1904), and is home to one of the most intricately shaped planetary nebulae ever discovered called the Spirograph Nebula (IC 418).

Spirograph Nebula (IC 418)– Spirograph Nebula (IC 418) is located about 1,100 light years away, and has an apparent magnitude of 9.6. There are no simple planetary nebulae, as all have complex structures that are in most cases still awaiting explanation, but this nebula can only be described as “physics become art”. The intricate arrangement of shells-within-shells of gas and dust seems like they were traced with a spirograph, hence the name, the Spirograph Nebula. There is as yet no clear explanation of the mechanisms and forces at work within the nebula, and as a result, it is probably one of the most intensely studied planetary nebula.

– Messier 79 (M79, NGC 1904) is a globular cluster located about 41,000 light years away that is 104 light years across and is thought to contain some 150,000 stars, many of which are red giants. M79 is believed to have originated outside of the Milky Way, in the Canis Major Dwarf Galaxy to be precise. However, the diminutive Canis Major Dwarf Galaxy is engaged in a gravitational tug-of-war with the Milky Way, and it seems highly unlikely that the smaller galaxy will escape being destroyed by the encounter.