Sand and Stars

Beautiful Carbon Stars

TW Horologii. DSS2 image.

6 Nov 2016

Carbon stars are absolutely beautiful stars. I’ll never tire of looking at them. Not only because of their vivid red colours, but also because I find it stupefying to view a sun nearing the end of its life, knowing that one day it will shed the soot it has dredged up from its nuclear innards, seeding the cosmos with the very element that makes life possible.

In these beautifully dark Kalahari skies some carbon stars smoulder like red-hot embers, others glitter like stellar rubies, and some are the blood-red of J.R. Hind’s famous blood-drop – R Leporis.  

Most carbon stars are stand-alone beauties; some are a member of an open cluster, some share the field with a star of a very different colour for a striking contrast. Each one is unique, fascinating, and absolutely gorgeous.

All carbon stars are variable stars and vary in brightness with periods that range from a couple months to more than a year. They  are shrinking when they brighten (increasing surface temperature) and expanding as they dim (surface temperature goes down). They appear reddest as they expand, especially near the lower end of the range. 

And talking of red…

it’s ridiculous how many reds the carbon stars display… it’s very difficult to describe the variations in red! The ones veering into orangey-red are easier… but red and different red and more different red? Not so easy!

Which brings me a peculiarity of observing carbon stars that has to do with the wonderful Purkinje Effect in the retina which makes red stars grow brighter (compared to white ones) the longer you stare at them.

Here are some of my favourite southern hemisphere carbon stars. 



10″ f/5 Dobs; 90x, 144x and 208x 


Ruby Crucis (DY Crucis) 

RA 12 47 24   Dec -59 41 41   Mag 8.0 – 12.0   Dist 4,077 ly    

Ruby Crucis is one of the loveliest sights in the sky – utterly gorgeous Mimosa is a dazzling diamond on a backdrop of black satin, and there, just 2′ away and in striking contrast, is tiny Ruby Crucis, a rich, deep, incandescent red. And how serendipitous is it that this magnificent and well-named ruby lies a mere nudge of the telescope away from the famed Jewel Box where a profusion of other stellar jewels can be seen… diamonds and rubies intermingled with topazes and sapphires in a profusion of sparkling light. 


TW Horologii

RA 01 12 33   Dec -57 19 17   Mag 5.52 – 5.95   Dist 1,370 ly

(The image at the top of the page.) TW Horologiismolders like a red-hot ember against the sky – bright, striking and brilliantly red. Absolutely gorgeous. It is made more gorgeous by the small galaxy PGC11984 that lies just 4′ away.


NP Puppis

RA 06 54 26   Dec -42 21 56   Mag 6.3 – 6.5   Dist 1,400 ly

This carbon star is a deeper red than the brilliant reds of Ruby Crucis and TW Horologgi. Its deep red has a touch of ruddiness to it that deepens the brilliance of its red. It’s set in a rich field of sparkling stars. Very lovely!


U Antliae

RA 10 35 12   Dec -39 33 45  Mag   5.3 – 6.0   Dist 840 ly

This is an extremely red carbon star! A beautiful red-hot chili red.


R Sculptoris

RA 01  26 58   Dec –32 32  35   Mag 5.8 – 8.8   Dist 1,500 ly

This carbon star is a glorious flaming orangey-red. 


Y Hydrae

RA 09 51 03   Dec -23 01 02   Mag 6.5 – 9.0   Dist 1100 ly

Superb. It is an intense, bright tomato red, set against a rich backdrop of sparkling stars.


V Hydrae

RA 10 51 37   Dec – 21 15 00   Mag 6.5 – 12   Dist –

Very rich orangey-red. I confess it’s so strange to gaze at a carbon star, knowing that stars just like it went through their metamorphosis and forged most of the nitrogen in Earth’s air as well as much of our planet’s carbon, the basis for all terrestrial life. 


Hind’s Crimson Star (R Leporis)

RA  04 59 36   Dec – 14 48 22   Mag  5.5 – 11.7   Dist 820 ly

The British astronomer,  John Russell Hind (1823 – 1895) discovered this carbon star in October 1834 and described it as being “… of the most intense crimson, resembling a blood-drop on the background of the sky; as regards depth of colour, no other star visible in these latitudes could be compared with it.” And it truly is absolutely gorgeous, a deep red blood-drop lying on a deep black satin sky in a beautiful field.

Seared into my memory is when Comet Lovejoy shared the field with Hind’s blood-drop back on 1 Jan 2015  – the big glowing puffball of a comet juxtaposed with the tiny, brilliantly red star. There is something entirely magical about seeing a comet, one of our strange, insubstantial visitors from outer space… but to see one flying past a small blood-red carbon star… I ask you, how much better can it get?


U Hydrae

RA 10 37 33   Dec -13 23 04   Mag 4.5 – 6.2   Dist 540 ly

Absolutely gorgeous. This carbon star is ridiculously red!

And to end..


NGC 2108 (Globular cluster with a carbon star)

RA 05 43 56.8   Dec -69 10 50   Dist 163,000 ly

NGC 2108. Image credit Hubble/ESO

NGC 2108 lies in the Large Magellanic Cloud and it is a rich “mid-aged” globular cluster, about 600 million years old. The most striking feature of this globular cluster’s beautiful Hubble image is the gleaming ruby-red carbon star to the lower left of the cluster’s center!

Alas for human eyes and no Hubble telescope… at 228x the globular cluster appeared as a fairly faint, round, knot, ~1 diameter with no resolution. 

Copyright © Susan Young 2016