Spiral galaxies are among the most beautiful objects in the Universe. Their grand, majestic nature is sweeping on a scale of hundreds of thousands of light years; their delicate arms are composed of a hundred billion stars blurred into a milky stream; and as for their cores… well, that’s a different story.
Let me present to you two surpassingly beautiful galaxies, each with a dark secret in its heart.
First is NGC 4698, as seen by Adam Block using the 0.8 meter Schulman Telescope at Mt. Lemmon in Arizona:
[Click to galactinate.]
NGC 4698 is relatively close, at a distance of 60 million light years. This image is lovely, with the faint outer arms clearly visible, the inner arms lined with clouds of dust like black pearls on a string. The core looks odd, though, which I noticed right away. It’s brighter than I would’ve expected, and appearing almost as if it’s popping right out of the plane of the galaxy.
And here’s a second spiral, M77, one with which I’m fairly familiar — I spent a long evening photographing it for an observational astronomy class in grad school. This remarkable image, however, was constructed by Andre vd Hoeven, who downloaded dozens of Hubble images of M77 from the online archive, and painstakingly assembled them into this amazing shot:
[Click to embiggen.]
Wee see M77 a bit more face-on than NGC 4698, and by coincidence it’s also roughly 60 million light years away. The red glow dotting the arms is indicative of star formation; those are vast gas clouds glowing from the heat of young, hot stars embedded in them. It too is thick with dust, and like NGC 4698 the core looks… odd. Too bright, too compact. In the high-res version you can also see a greenish glow off to the left of the core, like a searchlight shining in that direction.
So both of these galaxies look normal at a perfunctory glance, but clearly have something else going on, something not obvious that makes them special. A secret, if you will. Read More