A Crouching Rabbit Hides A Crimson Star

The rabbit Lepus crouches below the constellation Orion (upper right) in this photo taken earlier this week. See map below for the rabbit's outline. Details: 16mm lens at f/2.8, ISO 2500, 25-seconds. Photo: Bob King

Snowshoe hares hop around our yards and woods in the winter months, but I’ve yet to see one this year. Either their fur coats haven’t morphed from brown to white due to lack of snow or the rabbits making all those tracks in my yard are a different species.

A snowshoe hare in proper winter attire. Credit: USDA

The Y-shaped tracks of rabbits are a familiar sight in suburban and rural areas, but you’ll also find them in the sky. Our distant ancestors, who created the constellation outlines we still use today, populated the sky with plenty of animals including a rabbit named Lepus (LEE-pus) the Hare. The ancients were impressed with the hare’s swiftness and prodigious fertility, reasons enough to place it in the heavens along with the great hero Perseus and the mighty Hercules.

You’ll find the white bunny crouching under Orion the Hunter as if in hiding. And why shouldn’t it? A chilled hunter on a February night would enjoy a hot hasenpfeffer stew just like my grandmother used to make. To date however, Orion seems not to have noticed what’s under his feet, giving you and I the opportunity to get familiar with the sky bunny.

The bright stars Sirius and Rigel make Lepus easy to find even though its stars aren't particularly bright. Maps created with Stellarium

Orion is easy to find thanks to those three belt stars. Finding Lepus requires only a little hop below Rigel and a moderately dark suburban sky.

Look to the south-southeast as soon as it gets dark. To the right or west of Sirius is the rabbit’s tail – a short arc of stars – while directly below Rigel are two prongs of faint stars that form his ears. The ears are faint, but the rest of the rabbit’s form isn’t difficult to trace.  Whenever I see Lepus, I’m reminded of a kite or dragonfly until I “add” the fainter ears – then it looks like a proper rabbit.

R Leporis is a carbon star notable for its deep red hue. Start with Mu and point your telescope east to the little "trapezoid". From there, look a short distance north to find the star. It currently shines at about magnitude 8.5. Stars are shown to about 8th magnitude. R will stand out from the others by color alone.

Directly across from the ears not far from the star Mu Leporis is one of the reddest stars in the sky. Called R Leporis, observers have described it as a glowing red coal, a red bulb on a Christmas tree, a ruby. You get the idea. If you have any kind of telescope, be sure to take the time to hunt it down. Every time I see this star I’m amazed at the depth of its color.

R Leporis is a variable star ranging in brightness from around 6th magnitude to as faint as 12th over a period of 432 days superimposed on a second cycle lasting about 40 years.  Also known as Hind’s Crimson Star after its discoverer J.R. Hind, R Leporis’ light varies because it expands and contracts like a slow-beating heat.

You'll find few stars as intensely red as R Leporis. Carbon in the star's atmosphere is responsible for the intense color.

The sun fuses hydrogen into helium in its core and produces energy in the process. R is further along in its evolution than the sun and cooking up elements like carbon and oxygen in its core. Convective heat currents dredge the carbon up from deep below and spread it into a layer of “soot” in the star’s outer layers. The soot dims and reddens the star dramatically. When winds in R’s outer atmosphere blow the carbon into space, the star re-brightens until more carbon is dredged up and the cycle begins anew. The Crimson Star belongs to a special category of red giants called carbon stars.

So whether you enjoy hunting rabbits or rare carbon stars, Lepus is where it’s at.

7 Responses

  1. Jim

    Hi Bob,

    That star actually looks red in the picture. You sure that isn’t photoshopped? 🙂

    I will have to take a look again this weekend at Korrki.


  2. Jon Dannehy

    I finally managed to see it for the first time this morning. It is the reddest star I have seen. I am not very good at estimating magnitudes but I think it was brighter than it’s dimmest magnitude.

    1. astrobob

      I agree. Every time I return to R Leporis I can’t believe how red it looks. So Orion must have looked pretty nice, too I bet. Have you seen the nova? Take care – see you on the 9th!

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