Regulus, the brightest star within the constellation Leo the Lion, is a harbinger of spring within the Northern Hemisphere. It crept increased within the sky with every passing day in March and April, as winter favorites like Orion descended westward. And now, in Might, this blue-white star is sensible within the jap night sky as quickly because the sun goes down.
You’ll be able to find Regulus – also called Alpha Leonis – on the base of a star sample that seems like a backwards query mark. This sample, referred to as the Sickle, makes up the pinnacle and forequarters of Leo the Lion.
Regulus can also be one among three vibrant stars to make up the asterism referred to as the Spring Triangle.
Regulus ranks twenty first within the listing of brightest stars in our sky. Nonetheless, though it seems to be like one star to the attention, it’s really 4 stars.
Regulus is seen many of the 12 months
Round February 18, Regulus was reverse the sun. It rose above the horizon because the sun set, stayed up all evening lengthy, and reached its highest level due south (as seen from the Northern Hemisphere) at native midnight. By early April, Regulus was properly up within the southeast an hour after sundown. By early June, it’ll be excessive within the southwest an hour after sundown. Come early July, Regulus shall be low to the west an hour after sundown. And from mid-September by way of mid-February, Regulus shall be within the morning sky.
So, Regulus is seen at a while of evening all year long, aside from a couple of month on both aspect of August 22. Look in direction of Regulus round that date and also you’ll see the sun.
Planets and the moon cross close to it
Regulus is the one 1st magnitude star to sit down nearly squarely on the ecliptic, which marks the trail of the sun, moon and planets throughout our sky.
So vibrant planets typically cross close to Regulus. For instance, in mid-July 2023, each Venus and Mars will go to Regulus within the night sky. In truth, planets can typically occult – or cross in entrance of – Regulus. The final planet to occult Regulus was Venus on July 7, 1959. Then on October 1, 2044, Venus will occult Regulus once more.
And, each month, the moon passes close to Regulus. In some years, the moon occults this star as seen from Earth. There shall be a collection of 20 lunar occultations of Regulus from July 2025 to December 2026. Through the December 2026 occultation, Mars and Jupiter shall be close by.
A blue, egg-shaped star
Regulus is situated about 79 light-years from Earth. It’s a a number of system with at the very least 4 element stars. The primary star – Regulus A – is massive and blue with a spectral type of B8 IVn. Its floor temperature averages about 12,460 kelvin (21,970 levels F or 12,190 levels C), which is way increased than our sun’s floor temperature. Regulus A is 3.8 occasions the mass of our sun, about 4 occasions as broad, and nearly 300 occasions as vibrant.
Regulus spins on its axis as soon as each 16 hours. In distinction, our sun spins on its axis about as soon as each 27 days. This quick rotation causes Regulus A to bulge at its equator, so it seems oblate, or egg-shaped. In truth, if Regulus rotated only a bit sooner, it could fly aside! And Regulus just isn’t the one star with a quick spin. The celebrities Altair and Achernar are additionally quick spinners with flattened, oblate shapes.
Regulus is 4 stars
Look by way of a small telescope utilizing at the very least 50x magnification, and you’ll see Regulus as two objects separated by 177 arcseconds. The brighter of the pair is known as Regulus A.
The fainter one is Regulus B, a cool “orange” dwarf star with a spectral classification of K2 V. The B star has a mass that’s 80% of the sun’s, and it’s half as vibrant. It has a floor temperature of 4,885 kelvin (8,333 F or 4,612 C), and it shines at magnitude 8.1.
Regulus B, in the meantime, has its personal companion: Regulus C. At magnitude 13.5, it’s solely seen with highly effective telescopes. With simply 1/3 the mass of the sun, Regulus C is a red dwarf star with a spectral classification of M4 V. Regulus B and C are gravitationally certain to one another, and collectively they’re referred to as Regulus BC. The distances between B and C ranged from 4.0 to 2.5 arc seconds between 1867 and 1943. There aren’t any not too long ago out there measurements.
The fourth star within the system has by no means been straight resolved through imaging, however its presence is revealed by spectroscopic analysis of Regulus A. Astronomers suppose it could be a intently orbiting white dwarf star.
You might need heard of a star referred to as Regulus D. This doesn’t consult with the spectroscopic companion of Regulus A, however to a Twelfth-magnitude star that sits 212 arcseconds from Regulus. For many years, folks believed it to be a companion of Regulus, however current research from the Gaia satellite present this to be a background star not associated to the Regulus system.
A galaxy photobombs Regulus
Located 1/3 diploma north of Regulus is the galaxy Leo 1 – you may see it as a faint patch of sunshine within the picture beneath. Leo 1 is tough to see as a consequence of its proximity to Regulus. Albert George Wilson discovered it on photographic plates taken as a part of the National Geographic Society-Palomar Observatory Sky Survey in 1950. It could be one other 40 years earlier than anybody seen it visually.
Leo 1 is a dwarf galaxy, and a member of our local group. Newbie astronomers can view it, however this requires darkish skies and a big telescope.
A rex by another identify
The identify Regulus is from the diminutive type of the Latin rex, that means little king.
Historical Arab stargazers referred to as Regulus by the identify Qalb al-Asad, which implies Coronary heart of the Lion. It additionally bears the nickname Cor Leonis, once more that means Lion’s Coronary heart. Fittingly, King Richard I of England was additionally famously referred to as the Lionheart, or extra generally Couer de Lion in French.
There’s an excessive amount of mythology related to Leo, maybe the most typical story being that Leo was the Nemean Lion of the Hercules story. Some Peruvians additionally knew these stars because the Mountain Lion, whereas in China it was typically seen as a horse, and at different occasions as a part of a dragon. Christians within the Center Ages typically referred to it as one among Daniel’s lions.
Backside line: Regulus, the brightest star within the constellation Leo the Lion, is related to the arrival of spring and is distinguished in Might skies. It seems to be like a single level of sunshine, however is de facto 4 stars.
