Well, this is depressing: Fomalhaut b may not exist.

Fomalhaut is one of the brightest stars in the sky, and is only about 25 light years away — that’s close, on a cosmic scale. It’s young, not more than a few hundred million years old, and surrounded by a vast ring of dust, leftover from the formation of the star itself. The ring is about 20 billion km (12 billion miles) in radius, and has a sharp inner edge.

That last bit is important: the easiest way we know to make the inside edge that well-defined is if a planet is orbiting the star just inside the ring. Its gravity would draw in particles, sculpting what would otherwise be a fuzzy boundary into a clean-cut ring. Not only that, but the ring is off-center; again, that’s likely due to the gravitational influence of a planet.

In 2008, astronomers announced they had found that planet: it appeared in two different Hubble Space Telescope images (shown above; click to embiggen) separated by two years. During that time, it had moved a little bit, by just what you’d expect for a planet at that distance from the star. The news came out the same day as other planets were seen around a different star, and I, along with lots of other folks, made it a headline (see the gallery at the bottom of this post showing all the planets we’ve been able to detect directly in images). This was, after all the first direct detection of a planet orbiting a Sun-like star!

Except, maybe not so much. A new paper has come out (PDF) trying to see Fomalhaut b using the Spitzer Space Telescope. Spitzer is sensitive to infrared, where the planet is far brighter.

And what did they see? Nothing.

Dang.

This image is pretty damning for the existence of Fomalhaut b. It’s the Spitzer infrared observations of the star, with the star’s light carefully removed. On the left is the actual image, and on the right they artificially added a point of light calculated to be equal to what the planet would emit, in the same position the planet should be — that’s what Arrow 1 is pointing at. It should be one of the brightest things in the image (Arrow 2 points to an unrelated bright spot). And while it’s obvious on the right, nothing can be seen on the left, in the real image. In other words, the planet isn’t seen.

Dang again.

Looking over the paper, it’s clear the astronomers were very careful, and did a number of tests. There’s no known way to make a planet as bright as what was seen in the Hubble images yet invisible in the Spitzer images. If the planet were there, they should’ve seen it. Also, a recent study has shown that if the two images show the planet moving, it would be on an orbit that crosses the ring! That seems extremely unlikely, if not outright impossible. A planet that big and massive — more massive than Jupiter — would disrupt the ring in short order if it physically crossed it. That really does make it very, very likely this is not a planet^*.

So what is it? It’s probably a clump of dust orbiting the star, reflecting light from the star enough to show up in the Hubble images but not warm enough to show up in the infrared observations.

That’s too bad. If this is true — and it probably is — then that takes away one of the very few planets directly seen in telescopic observations. However, there are still plenty more, and those have been confirmed (again, see the gallery below). And that number will tend to increase as time goes on, even if every now and again it drops by one or two.

Hmph. I once wrote that destroying a planet is hard. Sometimes, all you need to do is try to observe it a different way, and poof! It’s gone.

And now I have to update that gallery, and all my previous pages about it too. Dang science. Always learning more stuff and changing what we thought we knew.

Image credit: Paul Kalas, U C Berkeley; NASA/Spitzer/Markus Janson et al.

^* I chatted with an astronomer friend of mine about this, and he agreed with the authors of this new study. "Overall," he wrote me, "it smells like fish.". I couldn’t help myself. I wrote him back: "Of course it does. Fomalhaut is the brightest star in Pisces!"

[Below is a gallery of exoplanets that have been directly imaged using telescopes on ground and in space. Click the thumbnail picture to get a bigger picture and more information, and scroll through the gallery using the left and right arrows.]

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In the heart of the Large Magellanic Cloud (one of the Milky Way’s many satellite galaxies), there lies a vast complex of gas called 30 Doradus. And inside that sprawling volume of space is the Tarantula Nebula, a star-forming region so huge it dwarfs even our own Orion Nebula. Thousands of stars are churning away in there, going through the process of being born.

And as they do, the hottest and brightest of them carve huge cavities in the nebula, heating the tenuous gas therein to millions of degrees. The result? This:

[Click to embiggen.]

I love this image! It’s a combination of observations from the Chandra X-Ray Observatory (in blue, showing the incredibly hot gas) and from Spitzer Space Telescope (in red, showing cooler gas). Those bubbles of hot, X-ray emitting gas are constrained by the cooler gas around them, but it’s likely the hot gas is expanding, driving the overall expansion of the nebula itself. However, it’s also possible the sheer flood of high-energy radiation from the nascent stars is behind the gas’s expansion… or it’s a combination of both. Astronomers are still arguing over this, and observations like this one will help figure out who’s right.

… but you know me. I love pareidolia, and there’s no way you can look at this image and not see a really angry screaming face, shrieking at that blue blob hovering in its way. That’s so cool!

And c’mon, NASA: you release this image two weeks after Halloween? Oh well, I’ll add it to my scary astronomy gallery anyway, which is after the jump below.

Image credit: X-ray: NASA/CXC/PSU/L.Townsley et al.; Infrared: NASA/JPL/PSU/L.Townsley et al.

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Speaking of Scorpius…

The constellation really is coincidentally shaped like a scorpion, complete with claws and a curved tail. If you look to the tail, near the stinger, there is a vast star-forming region that is not at all obvious in visible light. But if you point an infrared telescope in that direction, what you see is stunning to both the eye and brain:

Lovely, isn’t it? [Click to ennebulanate.]

That’s RCW 120, a bubble of gas several light years across, located 4300 light years from Earth. This image, taken by the Spitzer Space Telescope, shows the glow of gas we would consider bone-chillingly cold: hundreds of degrees below zero. It’s a false color image, since Spitzer sees in the far-infrared, where even these cold objects glow.

If you look to the center, you’ll see a blue star. That star may not look like much, but in fact is a mighty, massive O-type star, a powerhouse blasting out thousands of times as much light as the Sun. It also furiously emits ultraviolet light which pours out and eats away at the gas surrounding the star, carving this bubble tens of trillions of kilometers across. The light from the star is so intense it literally pushes on the gas like a snowplow through snow, collecting and compressing the material in a spherical shell around it. The result is what you see here: a cosmic soap bubble.

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I’ve been an astronomer a long, long time. Even so, I still sometimes get surprised at how different the same object can look when imaged in different ways. I just saw an excellent example of this… W5, aka the Soul Nebula:

[Click to ennebulanate.]

Pretty, isn’t it? It was taken by César Cantú, an amateur astronomer in Mexico. It’s not a true color picture. Not even close! For one thing, he used three filters which let through extremely narrow wavelengths of light (that is, the filters reject all light except for a very thin range of wavelengths; I’ve written about them before). Our eyes see broad ranges of colors, so immediately these filters change the very nature of the picture. Different atoms in space emit at different colors, and the filters he chose select for hydrogen, oxygen, and sulfur, which tend to emit light very strongly in gas clouds.

Not only that, he mixed and matched the colors. The hydrogen filter lets through red light, but he colored it green in the picture; oxygen is usually green but he made it blue^*; and sulfur is red which he actually did color red. This throws off my usual sense of what I’m seeing in a picture (I really am used to hydrogen being red and oxygen green) so it forces me to re-evaluate how I see this gas cloud.
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Spitzer Space Telescope is an orbiting infrared observatory. It ran out of coolant a few years back — needed to keep its highly sensitive IR cameras working — but before it did, it took this amazing image of a young star blasting out twin jets of matter:

Neat! [Click to collimatenate.]

The star is called Herbig Haro 34, and is only a few million years old. Stars that young rotate rapidly, have fierce magnetic fields, and thick disks of material surrounding them (out of which planets might form). All these things together help focus twin beams of matter called jets, which blast away at high velocity from the star’s poles. We see these quite often around young stars.

But the jets blowing off of HH 34 are weird. They aren’t symmetric.

Astronomers figured they should be. Sometimes the jets blow out knots of gas or sputter a little. And when that happens, whatever forces acting on the star and disk should act on both jets at the same time. But that’s not the case for HH 34: the jet on the right does the same thing the jet on the left does, but only after a 4.5 year delay!

Figuring this out at all wasn’t possible until this Spitzer image was taken. Before, visible light images only showed one jet:
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Things I love: astronomy, geeks, dorky humor, the scientific method.

So how cool is it that alpha geek Veronica Belmont did a funny video about science with the IRrelevant Astronomy folks!

And hey, Veronica pronounces Uranus correctly! She’s awesome.

If you like that video, then check out some of the others they’ve made with Friends of Bad Astronomy™:

• IRrelevant Astronomy: Dr. Wheaton edition
• Robot Wil Wheaton takes over the Universe
• Felicia Day collides galaxies

Tip o’ the anemone to Javier Pazos.