The galaxy in this image is known as M104. It was the 104th celestial object noted by Charles Messier in his 1774 catalogue of “extended objects.” It’s 31.1 million light years away, and is slightly smaller than our own Milky Way galaxy
The mass of M104 is estimated to be 800 billion solar masses. It has a diameter of 50,000 light years. In comparison, our own Milky Way galaxy has a mass of 1.5 trillion solar masses, and a diameter of 105,700 light years. M104 has a distinct dust lane where stars are forming, easily visible because it’s galactic disc is oriented at 6° to our line of sight.
M104 is a popular target for amateur astronomers. It’s not visible to the naked eye, but shows up in binoculars and small telescopes. Its central bulge is prominent and contains billions of stars. Its resemblance to a Mexican hat style earned it the moniker “Sombrero Galaxy.”
But what you see in visible light is never the whole story. Astronomers use multispectral imaging to extract more data from the object in question. Here’s another image of M104 taken by the Spitzer Space Telescope in infrared wavelengths:
This is a false color image. It was assembled from four separate images taken at: 3.6 μ (blue), 4.5 μ (green), 5.8 μ (orange), and 8.0 μ (red). All of them are considered infrared because their wavelengths are longer than those of visible light. The longer wavelengths allow them to pass through dust and gas that would block visible light. Hence the title of this post.
Spitzer uncovered the bright, smooth ring of dust circling the galaxy, seen in red. In visible light, because this galaxy is seen nearly edge-on, only the near rim of dust can be seen (in silhouette). Spitzer’s view shows the galaxy’s disk is warped, often the result of a gravitational encounter with another galaxy. Clumpy areas seen near the far edge of the ring are likely young star-forming regions — much like our own Eagle Nebula.
Multispectral imaging is not new. The images in this post are around 20 years old. But when I encountered them online recently I felt I had to share them. They’re a great example of the additional insights this technique can provide. Multispectral imaging is not limited to the electromagnetic spectrum — astronomers can now “look” at objects with neutrino and gravitational wave detectors. And no doubt other channels will be opened by future technological developments.
Next Week in Sky Lights ⇒ Santa’s Sleigh Sighted?