Starship Asterisk*

This is another extremely beautiful piece of art and science by Rogelio Bernal Andreo.

I love the mosaic of the Double Cluster and the Heart Nebula with today's popular comet "superimposed". Rogelio's picture makes me think of something that should have been obvious all along, but which hasn't exactly occurred to me earlier, namely that the Double Cluster and the Heart Nebula (and the Soul Nebula) are all part of a giant molecular cloud in the Perseus Arm of our galaxy, which is further out from the center of the Milky Way than the Orion Spur that our solar system belongs to.

So consider the nebulae that the Double Cluster must have been born from! Those nebulae must have been huge! Hey, the Heart Nebula is certainly big, but the (now evaporated) Double Cluster Nebulae would have dwarfed it, if they had existed at the same time as the Heart.

Note all the nebulosity that seems to permeate the field. Note, in particular, the feature that looks like a long dark dust lane between the two clusters of the Double Cluster!

I'm in awe of the tremendous effort that goes into producing Rogelio's enormous mosaics. As a Color Commentator, I feel obliged to point out that occasionally, very very occasionally, his color data for small parts of his huge mosaics hasn't been really good. I must keep that in mind when I look at the most interesting part of his picture, from a star-loving Color Commentator's point of view, namely the Double Cluster. Well, I think, I really do, that his color data for the Double Cluster is quite good. Therefore, please note the subtle colors of the Double Clusters. Any color picture of these majestic cluster twins will bring out the red supergiants that can be found in and around one to the two clusters, namely NGC 884. (Which one is that? Well, really, just look for yourself until you see the orange stars! )

The other cluster, NGC 869, doesn't contain any red supergiants. Okay, but now look at NGC 869 (which, if you still feel uncertain, is the more compact cluster of the two). There are no really bright and brilliantly orange-colored stars in it, no, but there are stars that are yellowish. And indeed, hot blue stars of type O and B become less blue when they give up hydrogen fusion in their cores and begin to expand. The brightest stars of NGC 869 are early B-type suptergiants, but they have become noticably less blue than they were when they were O-type stars on the main sequence. And the supergiants are also less blue than several of the smaller stars in the cluster, stars which are still on the main sequence. To me it is fascinating to see these different colors of the stars in NGC 869.

Of course it is also nice to see the beautiful aqua-colored comet here, a small interloper which is so incredibly close to us compared with the majestic clusters and nebulae in the Perseus Arm, but which certainly holds its own in this picture, seen from an Earthly point of view!

Ann