There are quite a few mysteries in astronomy; things we don’t understand. The vast majority of them are smallish in scope, things that can probably be solved with a little more work, more observations. These are more like questions than outright mysteries; things we just don’t have the answers to quite yet.
But then there are some that really are mysteries: unexpected oddities that, for now, defy explanation. One of these reared its head again recently, when observations by the ground-based Subaru and Keck observatories were combined with those from the space-based telescopes Hubble and Spitzer. It doesn’t look like much of a mystery — just a red smudge — but it pushes the boundaries of what we think the very Universe itself can do.
[Click to enbigbangenate.]
First, holy cow, what an image! Incredibly, nearly every single object in that picture is an entire galaxy, a vast collection of billions of stars. They’re also very distant; I doubt any of the bigger ones are closer than several billion light years away.
And lurking off to the side, where you’d hardly notice it, is that little red guy. Named GN-108036, it’s at the soul-crushing distance of 12.9 billion light years away. That means that the light we see here left that galaxy when the Universe was only a few hundred million years old.
As you might imagine, it may look faint, but at that distance it’s remarkable we can see it at all. But we do, because it’s amazingly luminous, perhaps the most intrinsically bright galaxy seen at that distance ever found. Of course, we don’t see too many galaxies farther away than this! And that’s part of the mystery.
Astronomers may have, for the first time, directly imaged a planet still in the process of formation, gathering material from a debris disk surrounding its parent star.
First: Holy Haleakala!
Second: note the use of the word "may". It looks to me like it’s real, though.
Third: Oh, you want to see the picture? Well, let me do the honors:
The alleged planet, called LkCa 15b, is the blue spot in the image. The red shows material which is most likely accumulating onto the planet itself, building up its mass. The central star isn’t seen in this image because its light has been blocked out so the fainter material near it can be seen. The star’s position is marked by the star icon.
The image is in the infrared, taken using the monster Keck telescope in Hawaii. What’s shown in red is light at a wavelength of 3.7 microns (roughly five times what the human eye can see) and blue is from 2.1 microns, about three times what we can see. Warm material around the star is best seen at these wavelengths. If this is a planet, it’s at a temperature of about 500 – 1000 K (440° – 1340° F), and has a mass roughly six times that of Jupiter, or about 2000 times the Earth’s mass.
So is it a planet? Read More
Mike Brown is an astronomer, specifically one who studies Kuiper Belt Objects, those giant frozen iceballs that haunt the solar system out past Neptune.
In fact, Neptune’s biggest moon Triton has a lot of characteristics similar KBOs — it may be one captured by Neptune — so observing it gives an interesting opportunity for a compare-and-contrast study. So this past weekend Mike was using the Keck telescope in Hawaii to observe Triton along with its (adoptive?) parent planet, and took this fantastic image of the pair:
[Click to poseidenate.]
This false-color image shows the two worlds in the infrared, specifically at a wavelength of about 1.5 microns, twice what the human eye can see. Methane strongly absorbs this color of light, so where Neptune (in the upper left) looks dark you’re seeing lots of methane clouds, and where it’s bright there are clouds higher up, above the methane. Triton is in the lower right, and is bright because it’s covered in ice which is highly reflective.
Now this is all very pretty and interesting and sciencey, but if you know me at all you know there’s more to this story.
Mike tweeted about the image, and I oohed and ahhhed at it, of course. But then he tweeted again, saying he was also observing Jupiter’s moon Europa, but it was too bright to get good images using the monster 10-meter Keck telescope. It "saturated the detector" which is astronomer-speak for "overexposed".
That’s funny, I thought. Neptune looks fine in the image, and the random noisy grain in it makes it clear Mike wasn’t anywhere near saturating the image. Now I know Europa is closer to the Earth, so it should look brighter, but geez, it’s a moon, and a lot smaller than Neptune. How could it be too bright to image?
It turns out my all–too–human and all–too–miserable sense of scale has failed me again. Math to the rescue!
NASA just released a new image of Jupiter that confirms what amateur astronomers discovered a few days ago: Jupiter’s Southern Equatorial Belt is coming back!
[Click to enzeusenate.]
This picture is a combination of three infrared images using the monster Gemini North Telescope. Infrared light at 1.69 microns (roughly twice the wavelength our eyes can see) is colored yellow, and shows the cloudtops, much like optical light images show. Far-infrared at 4.68 microns (wavelengths roughly 5-6 times what our eyes can see) is colored red, and comes from two altitudes: high up in the clouds where convected heat from the interior comes up, as well as from areas with little cloud cover allowing us to see the ambient heat from deeper in the atmosphere. Blue represents 2.12 microns (~2.5x what our eyes perceive) and comes from particles suspended high above the cloud deck.
The Southern Equatorial Belt is usually dark, and is somewhat lower down in Jupiter’s atmosphere than other clouds. Every now and again the wind patterns change, and white ammonia ice forms above the belt, hiding it. That pattern stays around for a while, then eventually breaks up. As that happens, we get patches of clearer air, allowing us to see down into the atmosphere farther, where the dark belt still lies.
That’s what’s happening here. The NASA image looks very much like those taken by amateur astronomers recently (shown here on the right)*. You can see the three dark comma-shaped features in the amateur image, which astronomers suspected were clear patches through the white ammonia ice, letting us peek at the lower-altitude belt below them. In the infrared those patches are bright, just as you’d expect from the warmer belt air, supporting the idea that the ammonia fog is clearing and the belt is ready to come back into view.
All in all, what astronomers are hoping is that we’ve caught the re-emergence of the belt as it’s happening: something never seen before with modern high-tech instrumentation.
And it’s very important to note how this was found: by dedicated amateur astronomers who watch Jupiter like hawks with every chance they get. Christopher Go, who first saw a bright spot on Jupiter signifying the belt’s return, was watching for it specifically: he knew from the last time the belt disappeared what to look for. And he should know what Jupiter looks like, since he monitors it constantly, and in fact actually caught the flash of light from an asteroid impact on Jupiter in June 2010.
Astronomy is an awesome science: it’s one of the few where dedicated "hobbyists" can contribute, and do so in a critical and timely way. It’s a big sky, with a lot to observe. And if I may say so, I’m thankful there are so many keeping an eye on it.