Life must suck for HD 189733b.
It’s a planet orbiting the star HD 189733, about 63 light years from Earth. It’s similar to Jupiter, being slightly more massive and slightly bigger. Unlike our own big brother, though, HD 189733b is far closer to its parent star, orbiting just about 4 million kilometers (about 2.5 million miles) above its surface! That means the cloudtops of the planet are at a scorching 840°C (1500°F), so hot that the atmosphere of the planet is getting blown away by the star itself, creating a comet-like tail of gas escaping from the planet.
And now, adding insult to injury, astronomers have discovered that the star is prone to cosmic hissy fits — and this may actually blow torch even more air from the planet.
[Illustration by NASA, ESA, and L. Calçada]
This pretty nifty: the researchers targeted the star and planet using Hubble in 2010 and didn’t see anything amiss. In 2011, though, they observed it with Hubble again, but also used NASA’s Swift satellite, which is sensitive to high energy emission like extreme ultraviolet and X-rays. They happened to be looking when the star erupted in a massive flare, quickly quadrupling its brightness in X-rays alone. And because the planet is so close to the star, it took the full brunt of this event, its atmosphere puffing up and actually getting blasted away into space by the fierce light from the star!
Just a few hours later, as seen from Earth, the planet passed directly in front of its star (like Venus did during its transit earlier this month). The atmosphere by this point was really streaming away from the planet in the aftermath of the flare, and was also blocking a bit of the star’s light. In the Hubble data the astronomers not only detected that absorption, but they could measure it to see how much hydrogen the planet was losing. It turns out something like 1000 tons of hydrogen was screaming away from the planet every second! And that’s a lower limit; they could only detect neutral hydrogen — that is, atoms that still held on to their electrons. There was probably plenty of ionized hydrogen they couldn’t detect.
NASA put out a short video that explains this as well:
Well, this is some very welcome and happy news: NASA’s 2012 Senior Review for Operating Missions has recommended to NASA that eight of the nine operating space-based astrophysics missions be extended in funding through fiscal year 2016, and NASA has complied!
This really is great news! The missions extended through FY 2016 are Hubble, Chandra, Fermi, Planck, Suzaku, Swift, XMM-Newton, and Kepler. The exception is the infrared observatory Spitzer, which ran out of coolant a few years ago but is running in an extended "warm" phase, still able to do science. It will be extended through 2015, which is earlier than hoped, but it could be worse. The details are in the report issued by the Senior Review (PDF).
I’m very excited specifically about Swift — a gamma-ray burst mission that I worked on years ago, and which has been operating for more than 7 years so far. But I’m even more excited about Kepler. This is fantastic — it has found
hundreds dozens of planets orbiting other stars, and has thousands more candidates listed that await confirmation. The reason this extension is so great is that the longer Kepler looks, the more likely it is to find lower mass planets in longer orbits. Big, massive planets orbiting close to their stars are easy to find, but ones more like Earth are much tougher. Kepler is right on the thin hairy edge of being able to detect them now, and this extension means a much higher chance it will succeed.
I strongly suspect — based on what we’ve already seen from Kepler coupled with the statistics and physics of exoplanets — that the signal from an Earth-like planet orbiting a Sun-like star in the habitable zone is already in the data we’ve received. It may be very hard to tease out, though, so having even more data, years worth of extra data, is more than a boon. It’s like being given the key to a treasure chest.
So overall I’m pretty darn pleased with this. Given the semi-apocalyptic nature of the last budget news we heard about NASA, this is like an oasis in the desert. Congratulations to all the people involved with these missions, and I’m looking forward to many more years of great science from our orbiting fleet of observatories!
Tip o’ the lens cap to Travis Metcalfe for alerting me to this news.
NASA’s little satellite that could, Swift, recently celebrated its seventh year in space. It blasted into orbit on November 20, 2004, starting a mission that would increase our understanding of the most violent events in the universe, and shatter cosmic distance records.
I wrote about Swift six years ago, on the first anniversary of its launch, and the funny thing is not a whole lot has changed except for the numbers. It’s still going strong after 2500+ days in orbit, and instead of dozens of gamma-ray bursts seen after one year, now it’s seen well over 600. Gamma-ray bursts are the mind-numbingly violent explosions of stars that signal the births of black holes, and each event releases as much energy in a few seconds as the Sun will over its entire lifetime. Happily, the Earth is nowhere near any potential GRB candidates (the nearest is about 7500 light years away, far enough that any damage it could do to us would be relatively mild), but if one were, say, 100 light years away, it would cook us like a whelk in a supernova.
Observing GRBs is Swift’s primary mission, and it’s performed outstandingly. It’s spotted what might be the most distant cosmic explosions ever seen, at 13.14 billion light years away from Earth. It saw the brightest GRB ever detected. But it’s also surveyed the sky, looking at high-energy light from sources near and far. It’s mapped our nearby galactic neighbors the Andromeda (shown above) and Triangulum galaxies in ultraviolet. It’s even observed near-Earth asteroids.
You can see the latest GRBs seen by Swift online, and there’s also a fun little iPhone/iPad app you can download that shows you Swift info, including the latest GRB detected and where Swift is in its orbit over the Earth.
I worked on Education and Public Outreach for Swift for many years, and it’s really nice to see it still pumping out fascinating and important science. Happy birthday to Swift and congratulations to the Swift team!
Image credits: NASA; Image credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)
The eyes of many astronomers — and the eyes of their telescopes — were aimed at the asteroid 2005 YU55 a few days ago, when it passed the Earth at the relatively close distance of about 320,000 km. One of those eyes was actually in space as well: NASA’s Swift satellite. This spacecraft was designed to look at the sky in the ultraviolet, X-ray, and gamma rays, all high-energy forms of light emitted by the most violent events in the universe: exploding stars and gamma-ray bursts.
But the Sun emits UV, and rock can reflect this light, too. So Swift observed YU55 as it passed us, and got this very interesting footage of it, what I think is the coolest I’ve seen so far:
[You can also watch it on YouTube if you prefer.]
Pretty neat, and by looking at the rock at different wavelengths, we can learn about its structure and composition, too.
But I know what you’re thinking: in the video, why did YU55 curve around as it moved? As it turns out, I was expecting this when I watched the video! What’s going on*?
The asteroid is in elliptical orbit around the Sun, but over the short period of time covered by this video — about 20 minutes — it’s essentially moving in a straight line. The reason the path is all bendy is because Swift itself is in motion! Swift orbits the Earth, circling us once every 90 minutes or so. As it moves around us, its viewpoint is changing, and that motion is reflected in the asteroid.
In late March of 2011, an extraordinary event occurred: a black hole in a distant galaxy tore apart and ate a whole star (I wrote about this twice at the time; here’s the original post, and a followup article including a Hubble image of the event).
Now, there’s more info: the black hole, lying at the center of a galaxy nearly 4 billion light years away, has about 8 million times the mass of the Sun. When it tore the star apart, about half the mass of the star swirled around the black hole, forming twin beams of matter and energy that blasted outward at a large fraction of the speed of light. The folks at NASA’s Goddard Space Flight Center made a great animation to show this:
The star was ripped apart by tides. The thing about black holes is, they’re small: this one was probably about 15 million kilometers across. A typical star is about a million km across (the Sun is 1.4 million kilometers in diameter, for comparison). This means the star could get really close to the black hole, and that’s why it was doomed. The force of gravity drops with distance, so as the star approached, the side of it facing the black hole felt a far greater force than the size facing away. That stretched the star, and the stretching increased as the star got closer. At some point, the force was so great it exceeded the star’s own gravity, and it could no longer hold on to its material. The black hole won — as they usually do.
In honor of Star Wars Day (May the Fourth be with you)…
I’ve been running around a lot the past week, and a few stories I wanted to write about slipped past me. One in particular was about an asteroid collision in the main belt between Mars and Jupiter; it was observed by the orbiting telescopes Swift and Hubble. All the more aggravating, I spent years working with both observatories (research with Hubble, and educational outreach with Swift)! I really wanted to write about this. Plus, asteroid collisions are cool, and y’all should get a chance to hear about them.
Happily for me, the folks at NASA (specifically Scott Wiessinger who makes videos for the space agency) put together a good story about the collision in easy-to-digest video form:
Awesome. Now back to my regularly scheduled running around.
I recently wrote about a mind-boggling event: astronomers capturing what are apparently the final moments in a star’s life as it was literally torn apart by a black hole.
Today, NASA has released some new pictures of the event, including this Hubble Space Telescope shot:
[Click to embiggen.]
I know, it may not look like much at first. But remember what you’re seeing: the violent death of a star ripped apart by the gravity of a black hole… and it’s happening 3.8 billion light years away! That’s about 40,000,000,000,000,000,000,000 kilometers, so the fact that we can see it at all is pretty amazing. And terrifying.
In this false-color Hubble image, the galaxy and explosion are marked. Pretty much everything you see in the picture is a distant galaxy, a billion of more light years away. Normally, the host galaxy itself would appear as a dot, at best with some small amount of fuzz around it, the glow of billions of stars reduced by the incredible distance. But the dying light of the star increased the galaxy’s brightness by a lot. A whole lot.
This image (click to greatly embiggen!) is a combination of visible light (white), ultraviolet (purple), and X-rays (yellow and red) from NASA’s Swift observatory, the satellite that first detected the explosion. While the spikes are not real — they’re just an optical effect from the telescope itself — it still speaks to the drama of what we’re seeing.
And so just what are we seeing?
On March 28, 2011, NASA’s Swift satellite caught a flash of high-energy X-rays pouring in from deep space. Swift is designed to do this, and since its launch in 2004 has seen hundreds of such things, usually caused by stars exploding at the ends of their lives.
But this time was hardly "usual". It didn’t see a star exploding as a supernova, it saw a star literally getting torn apart as it fell too close to a black hole!
The event was labeled GRB 110328A –a gamma-ray burst seen in 2011, third month (March) on the 28th day (in other words, last week). Normal gamma-ray bursts are when supermassive stars collapse (or ultra-dense neutron stars merge) to form a black hole. This releases a titanic amount of energy, which can be seen clear across the Universe.
And those last two characteristics are certainly true of GRB 110328A; it’s nearly four billion light years away*, and the ferocity of its final moments is not to be underestimated: it peaked at a solid one trillion times the Sun’s brightness!
Yegads. I’m rather glad this happened so far away. That’s not the kind of thing I’d like to see up close.
Although initially cataloged as a GRB, followup observations indicated this was no usual event. The way the light grew and faded seemed to fit better with a star getting torn apart. And what can do that to an entire star? A black hole. So instead of the star in question forming a black hole, it apparently literally fell victim to one!
The observations indicate the black hole in question may have as much as half a million times the mass of the Sun, meaning it’s very probably a supermassive black hole in the very center of a distant galaxy. Hubble Space Telescope observations (not yet released to the public) also place the event very near the center of a galaxy, which is consistent with this scenario.
So what happened?
NASA’s Swift satellite is a modern success story: designed to peer at the Universe in ultraviolet, X-rays, and gamma rays, it is on constant lookout for gamma-ray bursts, explosions so vast they are second only to the Big Bang itself.
Swift scans the skies, constantly observing, always on its toes for that fleeting blast of high-energy light. But it also does other science as well; an orbiting camera like that has many uses. For three months in 2008, astronomers used Swift to target the nearest major spiral galaxy like our own: M31, the Andromeda Galaxy. And what they got was this gorgeous picture:
Wow. You absolutely want to click that to embiggen it most cromulently — you’ll get a whopping 4400 x 200 pixel version.
This image is incredible, both scientifically and logistically. It is the combination of 330 images, totaling 24 hours of solid observations, and amounted to a hefty 85 gigabytes of data. It covers three UV wavelengths: 192.8, 224.6, and 260 nanometers, which are just outside the range the human eye can see.
The image is huge; the full Moon would just fit over the apparent size of the central bulge of the galaxy. Over 20,000 individual sources of ultraviolet light can be found. Some science can be seen just with just a glance: for example, the light coming from the spiral arms is clumpy, and from the bulge it’s smooth. The arms are where you find patches of giant gas clouds forming newly born stars; the most massive of these blast out UV light and fierce winds which make the clouds themselves glow in UV.
But the bulge at the core is smooth, because stars there are old; star formation long ago ceased in the galactic center. The UV glow is mostly from tightly packed stars, not from gas. There are so many stars that the individual sources blend together into what looks like a continuous glow (not unlike a digital image itself, where individual pixels blend together to make what looks like a smooth picture).
This image is the most detailed ever taken of our big neighbor in the ultraviolet, and I have no doubt it will be used as an atlas for higher-resolution cameras aboard Hubble and future spacecraft. Pictures like this are scientifically incredibly useful; they are roadmaps we can use to plan out our travels ahead.
And they are also just very, very cool.
Image credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)