I have no shame in admitting I love face-on spiral galaxies. Scientifically, of course, they’re fascinating; spread out in front of us are all the inner workings of a galaxy. It’s like having an X-ray of human body in front of you, making it easier to understand anatomy.
But their beauty… well. The scope and grandeur of a face-on spiral is unparalleled, I think, in astronomy, or perhaps any field of science. But don’t take my word on it. See for yourself.
[Click to galactinate, or get a 1900 x 1200 desktop image.]
This is the wonderful nearby spiral M101, and is a composite of no fewer than four orbiting observatories! It has images from Hubble, Spitzer, Chandra, and GALEX. These represent (in order) observations in visible light (shown as yellow in the picture), infrared (red), X-ray (purple) and ultraviolet (blue).
Each shows a different aspect of the galaxy. Visible light shows stars and gas, infrared indicates warm dust, X-ray show hot gas and energetic objects like supernovae and black holes, and ultraviolet is where young stars glow and light the gas around them. Each observation is incredibly useful to a scientist, but combining them together makes them even more powerful.
The things to look for are where colors overlap, and where they don’t overlap. For example, in the outer arms you can see dust and gas and young stars all together, showing where stars are born. In the inner regions of the galaxy the infrared and visible images are next to each other, parallel spirals. Dust blocks visible light, so where there’s lots of dust there’s little light we can see, and vice-versa.
You have to be careful interpreting images like this, though. The outer arms, for example, are blue. You might think this means they’re only giving off ultraviolet light. But you have to account for the different telescopes’ field of view, exposure times, and more. Each of those affects what you see no matter what the galaxy itself may be doing. Images like the one above are useful, even important, but it’s also important to remember their scientific limitations.
But artistically? That’s a different matter. All together.
Image credit: X-ray: NASA/CXC/SAO; IR & UV: NASA/JPL-Caltech; Optical: NASA/STScI
If you were wondering what was going on with the bright new supernova in the spiral galaxy M101, it’s now getting very difficult to observe due to its proximity to the Sun in the sky. But happily my friend, the accomplished astronomer Travis Rector, got a shot of it using the Mayall 4-meter telescope at Kitt Peak National Observatory. I would venture to say it’s one of the prettiest ones I’ve seen so far:
[Click to Chandrasekharenate.]
This was taken on September 18th, and the supernova is the bright blue star above and to the right of the center of the picture (to the left of the fuzzy red nebula). Pictures like this are important in pinning down the exact location of the supernova in the galaxy, so that after it fades the potential prescursor star can be found (though in this case, we already have pretty decent Hubble images of the field). Also, of course, big telescopes with sensitive detectors can give very accurate brightness measurements, which are absolutely critical in understanding how these objects change with time. This particular flavor of supernova is key to our understanding the size and scale of the Universe itself, so the more data — and the more accurate the data — we have, the better.
Image credit: T.A. Rector (University of Alaska Anchorage), H. Schweiker & S. Pakzad NOAO/AURA/NSF
– AAS 15: Travisty of astronomy (links to many of Travis Rector’s must-see photos!)
– Supernova update: it’s peaking now!
– M101 supernova update
– AstroAlert: Type Ia supernova in M101!
– Dwarf merging makes for an explosive combo
– Hubble delivers again: M101
A couple of weeks ago, astronomers spotted a star exploding in the nearby face-on spiral M101. They quickly determined it was a Type Ia, the kind used to calibrate the cosmic distance scale, and therefore a star of exceeding importance: we don’t see them close by (well, if 20+ million light years is "close", which it is to astronomers) very often. This one promised to get bright enough to study extremely well, which will help us understand these "standard candles" better.
Astronomers at Oxford University got a great shot of the galaxy and exploding star this week using a telescope located in California:
[Click to galactenate.]
The supernova is labeled. It was found by the Palomar Transient Factory, a group of folks looking for nearby supernovae, and was given the temporary name PTF 11kly; the official designation is SN 2011fe, the 136th supernova seen so far in 2011 (they’re named alphabetically for a given year, so the first 26 are 2011a – z, the second 26 are 2011ba – bz, etc.). This image was taken using a 0.8 meter telescope at the Las Cumbres Observatory Global Telescope Network; that’s a relatively small ‘scope, which tells you this a pretty bright object!
In fact, it appears to be reaching its peak brightness right now, and should be visible in binoculars. If you have a good view of Ursa Major, currently in the northwest at sunset, finding it shouldn’t be too difficult. Any decent star chart will show it (here’s one on wikipedia, for example). It’s raining here in Boulder (figures) but I’m hoping to get a chance to see it with my binoculars soon. Supernovae usually brighten for a couple of weeks and then fade more slowly, so if you can’t see it tonight or tomorrow it’s not critical, but of course the sooner you look the better.
Image credit: BJ Fulton/LCOGT. Tip o’ the accreting white dwarf to Dan Vergano (you should follow him on Twitter for lots of sciencey updates).
Attention all astronomers! There is a new Type Ia supernova that has been seen in the nearby spiral galaxy M101, and it’s very young — currently only about a day old! This is very exciting news; getting as much data on this event as possible is critical.
Most likely professional astronomers are already aware of the supernova, since observations have already been taken by Swift (no X-rays have yet been seen, but it’s early yet) and Hubble observations have been scheduled. Still, I would urge amateur astronomers to take careful observations of the galaxy.
[As an aside, I’ll note that this supernova won’t get bright enough to see naked eye and poses no threat at all to us here on Earth. It may be visible in decent-sized telescopes, though, and as you’ll see this may be a very important event in the annals of astronomy.]
So why is this a big deal?
Spiral galaxies are among the most beautiful objects in the sky, and one of the most beautiful of them is M101, also known as the Pinwheel Galaxy. It’s a reliable favorite among amateur astronomers because it’s big, bright, and located near the north pole of the sky, so it’s easy to find for a big part of the year.
I’ve seen it many times through a telescope, but not quite like the way NASA’s Wide-field Infrared Survey Explorer (WISE) saw it: glowing fiercely in colors our eyes cannot detect:
[Click to galactinate.]
This image shows the galaxy in the far-infrared. What you see here as blue is actually starlight; green is from long organic compounds called PAHs, and red is from glowing dust, warmed by nearby star formation. Look at the gigantic red clouds where stars are being born! Thousands of these have been catalogued in the Pinwheel.
It’s actually an immense galaxy, twice the diameter of the Milky Way and possessing as many as ten times the number of stars. Our galaxy is no lightweight, but the Pinwheel is a monster. I wrote about it when Hubble released a gorgeous and incredibly detailed image of it back in 2006. There’s also a spectacular Spitzer image of it as well, which is also in the infrared, though in a different part of the IR spectrum.
The WISE mission shut its eye earlier this year when it ran out of coolant to keep its detectors cold (warm objects emit lots of IR, so keeping things cold prevents the detectors themselves from glowing in the very light they’re designed to see), but it surveyed the entire sky, returning a whole lot of data. I imagine we’ll be seeing more pictures like this coming from the database, as well as lots of amazing discoveries as scientists pore over it. The mission itself may be done, but the information it gave us goes on.
Image credit: NASA/JPL-Caltech/UCLA