We are please to announce the release of Annals of the Deep Sky – Vol.6
Stars and galaxies, like grains of beach sand, each have their own evolutionary story that can be traced back to the primordial universe. Volume 6, which abounds in through the-looking-glass examples of stars and deep-sky objects. Covering the constellations of Chamaeleon, Circinus, Columba, Coma Berenices and Corona Australis.
Alpha Chamaeleontis for example, a star that is not what it appears. Its spectrum resembles an old giant, but its luminosity and temperature indicate that it’s a younger dwarf. NGC 2915 optical observations show it to be a modest-size galaxy with a nucleus that exhibits coarse star streams. Radio observations, however, reveal that the galaxy is immersed in a vast pool of neutral hydrogen with a radius at least a dozen times that of the visible disk.
The Circinus Galaxy (ESO 97-13) exhibits both Seyfert 1 and Seyfert 2 characteristics (broad and narrow emission lines), while its ratio of infrared to nonthermal radio luminosity resembles that of the starburst galaxy M82 in Ursa Major. It apparently harbors an active galactic nucleus cloaked in a dusty torus that has produced a bipolar radio lobe.
Columba, too, has its cabinet of curiosities. NGC 2188, one wonders how it came to look like a bar in a barred galaxy, but without a surrounding disk. It was once theorized that this galaxy was not a disk system, per se, but a spinning rod!
There is simply no end to stellar and nonstellar curios in Coma Berenices, beginning with its alpha star Diadem, a close binary that is seen virtually edge-on. Because the components are so close in brightness, making it difficult to differentiate the primary from the secondary, it took years before a period. NGC 5053, a globular cluster that may have been plucked by our galaxy from the Sagittarius dwarf spheroidal galaxy, and M53, a first-generation globular cluster, i.e., one of the oldest known in our galaxy: age, 12.7 billion years. And, of course, we have to include NGC 4676 AB (Arp
242), known as the Mice for their double-tailed structure, the result of a close interaction that will lead to their eventual merger and reincarnation as an elliptical galaxy hundreds of millions of years hence. Other galaxies, such as NGC 4565 (the Needle Galaxy), M95 (with its prominent bar), the grand design spiral M100, and the two supergiant central elliptical galaxies in the Coma Cluster, NGC 4889 and NGC 4874, are just beautiful systems to study visually or imaging.
And let’s not forget little Corona Australis, the Southern Crown, which despite its southerly location can be seen in the southerly latitudes of the Northern Hemisphere. This little jewel hosts a very old globular cluster (NGC 6541) and a binary galaxy (NGC 6768), with overlapping halos.