First it was there, then it wasn’t, and now it just may be back again: the first exoplanet directly observed orbiting a normal star, Fomalhaut b, has had quite a ride.
[This post has a bit of detail to it, so here's the tl;dr version: new analysis shows an object orbiting the star Fomalhaut may actually be a planet, enveloped in a cloud of dust. We can't for sure it exists, but we can't say it doesn't, either! Earlier claims of it not existing may have been premature. Also, at the bottom of this post is a gallery of direct images of exoplanets.]
First a brief history. In 2008, astronomers revealed huge news: they had successfully taken images of planets orbiting other stars. Up until then, the only evidence we had of exoplanets was indirect, either by their tugging on their stars which affects the starlight, or by having them pass between their stars and us, dimming the starlight.
But, along with Gemini telescope pictures of a family of planets orbiting HR 8799, Fomalhaut b was the first planet ever seen directly, as a spark of light in a picture. Here is that historic shot:
It’s Sauron’s eye! [Click to embiggen.]
The object is labeled. It doesn’t look like much, but the important thing to note is that it moved between 2004 and 2006 (see picture below), and it was definitely in both images taken two years apart. That means it wasn’t some bit of noise or detector error. Moreover, the movement was consistent with what you’d expect from a planet. Not only that but the star Fomalhaut is surrounded by a vast ring of dust – Sauron’s eye – and the inner edge of the ring is sharp. That’s what you would expect if a planet was orbiting inside the ring; its gravity sweeps up the dust on the inside of the ring. Given the brightness, we were looking at an object with a few times Jupiter’s mass, much smaller than a star, so definitely a planet.
All in all, it looked good, and it looked real.
Then, in early 2012, some astronomers threw a Pluto-esque wet blanket on the news. A planet that big should be bright in the infrared. Fomalhaut is a youngish star, only a few hundred million years old. Any planet more massive than Jupiter should still be hot, radiating away the heat of its formation. They looked for it in the infrared, and it wasn’t there.
To make things worse, they found that if you extrapolate the orbit of the supposed planet using its movement, it should cross the ring. That’s bad, because its gravity would disrupt the ring after a few million years tops. The ring is there, so that planet means the planet must not be.
Their conclusion: this object is a clump of dust, a cloud, orbiting the star. That fits the data, and a planet doesn’t. Cue the sad trombone.
But wait! We’re not done!
Looking up into the night sky, it seems like you can see forever. If you use binoculars or a telescope that feeling is, literally, magnified – you can see thousands, millions of stars.
But what you’re seeing is barely scratching the depths of the Universe. You’re looking out a few thousand light years into a galaxy a hundred thousand light years across, in a Universe where we can see distant galaxies over 10 billion light years away.
We build bigger telescopes so we can see those far-flung objects, and we even put them in space so our bothersome atmosphere doesn’t interfere with the view. The most famous is of course the Hubble Space Telescope. It’s hard to describe just how much of an impact this Grande Dame of astronomy has had on our perception of the Universe… though looking into the Hubble Deep Fields, you get a glimmer of it. In 1995, Hubble stared at one spot in space for over 140 hours, creating the first Deep Field. It revealed thousands of galaxies at tremendous distance, showing us that the sky is filled with galaxies.
The region of the sky for the first Deep Field was chosen because it was nearly devoid of stars and known galaxies, objects that would interfere with their more distant brethren. But what does that field look like from the ground? Astronomer Detlef Hartmann decided to tackle this question, and has done us all a favor by showing us. Using a 44 cm (17") telescope he built himself, he took an incredible 247 five-minute images to create this extraordinary picture with a total of 20 hours of exposure… and then lets it morph into the actual Hubble Deep Field to compare them:
[The image is an animated GIF that weighs in at nearly 6 Mb, so it may take a while to load. I urge patience; it's worth it. Click to edwinenate.]
Let me be clear: Detlef’s image is amazing. It’s a tremendous effort by an "amateur"*, and shows dozens of the galaxies (and the same scattered handful of stars) in the Hubble image. It’s an amazing achievement. A bigger telescope would show more galaxies, of course, and resolve them more clearly, but even the biggest telescope located on the surface of our planet needs to peer through the soup of air above it, which dims the faintest galaxies into obscurity. You need to get above our atmosphere to see the cosmos as clearly as possible.
And when you do, look at what Hubble shows us. That tiny region of the sky – easily blocked by a grain of sand held at arm’s length – contains thousands of galaxies, each a sprawling city of billions of stars. It represents a relatively random part of the sky, so you can expect to see something like it no matter where you point a telescope… and that picture shows just one 24-millionth of the entire sky.
The implication is clear: there are hundreds of billions of galaxies in our Universe. That in turn means there are sextillions of stars, each a Sun, and many, if not most, circled by a retinue of planets.
It’s the most ironic aspect of any science I know: it crushes my sense of scale and ego into dust, but also fills me with wonder and amazement that we can know such things, and be a part of it.
As is so often the case in science, you don’t know what you’ll get when you build a new instrument. You build it for one reason or for many, but later on new applications arise, new ways to use it. And sometimes, years down the road, it’s utilized in a just such a new way which profoundly changes how you see the Universe, how you see yourself and your place in it, and in a way you had may have only had an inkling of when you started out. The Hubble Deep Fields are perfect examples of this.
We knew intellectually the Universe was deep, and our place in it infinitesimal yet rare and beautiful. But Hubble showed that to us.
Image credits: R. Williams (STScI), the Hubble Deep Field Team and NASA; Detlef Hartmann. My deep thanks to Salvatore Iovene (who hosts AstroBin where Detlef’s image is displayed) for letting me know about this amazing work.
* Oh, that word. Detlef built his own ‘scope, took hundreds of these images, then combined them in a painstaking and difficult process that probably took him many, many hours. The word "amateur" has many connotations, but as usual here when I use it, I simply mean someone who is not a career astronomer. Detlef clearly has it going on.
- Revealing the Universe: the Hubble Extreme Deep Field
- BAFact Math: The Sun is mind-crushingly brighter than the faintest object ever seen. Seriously.
- Another record breaker: ultra-deep image reveals ultra-distant galaxy
- What does a half million galaxies look like?
- Hubble digs deep to see baby galaxies
On April 24, 2007 – the 17th anniversary of Hubble’s launch – the Space Telescope Science Institute released a devastating picture of the Carina Nebula, a ridiculously complex and gorgeous star forming region about 7500 light years from Earth.
Here’s the picture:
Like I said, gorgeous! [Click to keelhaulenate.]
Any structure with that kind of detail in it is going to spark your brain, making you see all sorts of things in it like faces, animals, and so on. This is called pareidolia, and is one of my favorite things of all time. It’s so fun, in fact, that the folks at the Institute are holding a monthly contest which they call the Hubble Heritage Creative Challenge [Facebook link], and this month’s contest is to find examples of pareidolia in the Carina Nebula. They have a few that have been submitted already on display.
It’s not hard to find things in the nebula. Either click the image above, or just go to the Hubble site with a zoomable image of Carina and start panning and scanning! You’ll find tons of stuff.
In fact, in a post I wrote back when this image was first released I pulled out some choice objects to discuss, and one of them is the famous finger you see here. I wouldn’t suggest submitting it, though: the judges may rule against you prejudicially given the attitude conveyed.
But if you find something good, you can win a print of a Hubble image! The artwork with the most "Likes" will win. But hurry: the contest ends October 19.
Thanks to my friend Tiffany Davis at STScI for letting me know about the contest.
- Desktop Project Part 26: Carina will keel haul your brain
- Hubble’s 17th: Chaos, birth, and near death
- Supernovae popping off like firecrackers in Carina
- Hubble celebrates 20 years in space with a jaw-dropper
Hey, it’s been way too long since I’ve done a Spiral Galaxy Monday, so here’s a good one. My love for big splashy spiral galaxies is well documented, but sometimes I also love one when it gets a bit edgy.
Which is why I present to you NGC 4183, a very nearly edge-on spiral in the constellation of Canes Venatici, the hunting dogs:
[Click to galactinate.]
This Hubble image is pretty amazing: you can see individual stars in the galaxy, even though it’s 55 million light years away! That’s 550 quintillion kilometers, in case you’re wondering.
And astronomers consider that to be close by as galaxies go.
This unusual image is a combination of visible light from the galaxy plus light in the near-infrared, just outside what the human eye can detect. You can see bluer regions where stars are busy being born, the more massive and hotter newborns lighting up their surrounding gas. You can also see long clouds of dust – complex chains of organic molecules – which are opaque to visible light, so they block the starlight behind them.
This galaxy is somewhat similar to our own. It’s a bit smaller, 80,000 or so light years across, but like ours it’s an open spiral (which, even though it’s edge-on, can be determined in a number of ways, including radio observations which trace the arms of the galaxy). The observations making up the image were taken as part of a project using Hubble to characterize nearby edge-on spirals, and the image itself was put together by Luca Limatola as part of the Hubble’s Hidden Treasures project – encouraging people to find overlooked Hubble observations and create beautiful images from them.
I’d say this counts.
ESA/Hubble & NASA. Acknowledgement: Luca Limatola
Astronomers using the Hubble Space Telescope have created the deepest multi-color* image of the Universe ever taken: the Hubble Extreme Deep Field, a mind-blowing glimpse into the vast stretches of our cosmos.
Check. This. Out.
Yegads. [Click to cosmosenate, or grab the bigger 2400 x 2100 pixel version.]
This image is the combined total of over 2000 separate images, and the total exposure is a whopping two million seconds, or 23 days! It’s based on the original Hubble Ultra Deep Field, with new observations added in since the originals were done. It shows over 5500 galaxies – nearly everything you see in the picture is a galaxy, an island universe of billions of stars. Only a handful of individual stars in the foreground of our own galaxy can be seen.
Here’s some detail from the image:
The variety of galaxies is amazing. Some look like relatively normal spirals and ellipticals, but you can see some that are clearly distorted due to interactions – collisions on a galactic scale! – and others that look like galaxy fragments. These may very well be baby galaxies caught in the act of forming, growing. The most distant objects here are over 13 billion light years away, and we see them when they were only 500 million years old.
In case your head is not asplodey from all this, I’ll note that the faintest objects in this picture are at 31st magnitude: the faintest star you can see with your naked eye is ten billion times brighter.
I’ll note that the purpose of this and the other deep field images is to look as far away and as far back in time as we can to see what the Universe was like when it was young. The wealth of data and scientific knowledge here cannot be overstated.
But I suspect, in the long run, the importance of this and the other pictures will be their impact on the public consciousness. We humans, our planet, our Sun, our galaxy, are so small as to be impossible to describe on this sort of scale, and that’s a good perspective to have.
But never forget: we figured this out. Our curiosity led us to build bigger and better telescopes, to design computers and mathematics to analyze the images from those devices, and to better understand the Universe we live in.
And it all started with simply looking up. Always look up, every chance you get. There’s a whole Universe out there waiting to be explored.
The folks at Hubble will be holding a public interactive discussion of the HXDF image on Google+ at 13:00 Eastern (US) time on September 27th, where you can ask astronomers questions. Tune in and learn more!
Image credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
* In 1998 a single-color image was taken with the STIS camera on Hubble, and reached similar depth. It would take some serious analysis to know which image sees fainter objects!
- Astronomers have found when and how the cosmic fog was lifted (a brief history of the young Universe)
- Another record breaker: ultra-deep image reveals ultra-distant galaxy
- Record-breaking galaxy found at the edge of the Universe
- Hubble digs deep to see baby galaxies
I am constantly amazed and awed by the sheer beauty of planetary nebulae – the gorgeous structures created as stars die.
Among the most astonishing of them is NGC 7026, a youngish nebula about 6000 light years away in the constellation Cygnus, the Swan. Here’s a stunningly beautiful picture of it from the Hubble Space Telescope:
[Click to enlepidopterate.]
Planetary nebulae (or PNe for short) like this are sometimes called "butterfly nebulae" because of their shape. It’s easy to see why; there are two big lobes that are roughly shaped like butterfly wings. The history of those lobes is complex.
You can see the central star, right in the middle. That used to be a star much like the Sun, though more massive and hotter. As it ran out of fuel in its core, it swelled up to become a red giant. It started to blow a slow, dense wind of gas, like the solar wind but much thicker. This expanded into space around it. Eventually, the star blew off so much of its outer layers that the hotter lower layers were exposed. This causes the wind to speed up substantially and get much thinner. The fast wind catches up with and collides into the slower, older wind, carving all manners of weird shapes.
The overall shape of the nebula depends a lot on two things: material outside the star into which the winds are flowing, and what shape the winds themselves are.
You might think the winds would expand in a sphere, but there are forces that can change that. If the central star is a binary, for example, centrifugal force can cause the slow wind to be flattened, like someone sitting on a beach ball. It’s thicker along the equator as it expands. When the fast wind slams into it, it get slowed a lot by this thicker waist, but the thinner gas along the poles means the fast wind can plow on through. What finally happens is the formation of a double-lobed structure like a bowling pin with a ring around the middle… just like NGC 7026! The ring around the middle isn’t obvious in this picture, but you can see how the pinched waist is brighter, which is a tell-tale sign of a ring (similar to how some nebulae look like smoke rings).
That explains the gross structure. But look at all the detail! Those fingers of stuff pointing inward toward the middle, the complex lobe structure? What gives there?
The clue comes from the location: Cygnus the Swan is a part of the sky where we’re looking into the plane of our flat Milky Way galaxy’s disk. That means there’s more gas and dust there than usual, and NGC 7026 is in the thick of it. The lobes of gas from the star are slamming into all that junk, creating these weird patterns. Those fingers are very common when hot, fast gas flows past denser, cooler gas (it’s called a Rayleigh-Taylor instability, if you want details).
I strongly suspect that explains the butterfly-shaped structure as well. The junk surrounding the nebula is not smooth, and is denser in some places in others. Where there’s less material, the winds from the star can poke through more easily and expand. If you’ve ever blown up a balloon with a weak spot in it you get the same thing. It’s essentially a hernia!
I read a couple of research papers about NGC 7026, and this idea does seem to fit with what’s observed. The lobes are also filled with very hot gas that emits X-rays, and that also makes sense if the lobes are still plowing into surrounding material; the hot gas hasn’t been able to escape because the lobes are closed.
Which means one more thing: eventually all that material may blow out of that cloud, popping it. When it does – in what’s called a "blowout" – the gas will escape and it’ll probably form long, weird, filaments like a shredded balloon. And that means, if it’s even possible, this object will become even more interesting, and even more beautiful.
Image credit: ESA/Hubble & NASA
Every now and again I see something so simply stunning that it leaves me speechless.
OK, I’m kidding; I’m never speechless. But this really is flipping amazing.
Tell me: which of these two pictures below is a Hubble Space Telescope image of the nebula Sharpless 2-106, a massive young star blasting out jets of gas, and which is a painting by my delightful space artist friend Lucy West?
… or …
You might be forgiven if it’s not easy to tell. Of course, the one on the bottom has Lucy’s signature on it, making this task somewhat easier. But seriously, if I showed you just the art itself, you’d have a hard time telling which is which. FYI, it’s acrylic on canvas, and is 30" by 48".
Lucy is seriously good. I met her at SpaceFest IV and we hit it off instantly – she’s smart, funny, and holy cow, what an amazing artist. When she posted that photo of her painting on Facebook, I immediately asked her if I could put it up here. Wow.
And she picked a heckuva target to paint. Sharpless 2-106 is a complex, gorgeous nebula, which I explained in detail in an earlier post. If you want – and you do – here’s a higher-res version of the Hubble shot, and Lucy has a somewhat bigger shot of her painting on her website. She also has a look at the process she did to make the painting , too, which is fascinating.
Do yourself a favor, and do what I do: surround yourself with smart, talented friends. They make life far more interesting, and far more fun to live.
Image credits: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Lucy West (used by permission)
[BAFacts are short, tweetable astronomy/space facts that I post every day. On some occasions, they wind up needing a bit of a mathematical explanation. The math is pretty easy, and it adds a lot of coolness, which I'm passing on to you! You're welcome.]
Today’s BAFact: How much brighter is the Sun than the faintest object ever seen? About Avogadro’s number times brighter.
Yesterday and the day before I wrote about how much brighter the Sun is than the Moon, and how much brighter the Sun is than the faintest star you can see (note that here I mean apparent brightness, that is, how bright it is in the sky, not how luminous it actually is). I have one more thing to add here.
Years ago, I worked on a Hubble Space Telescope camera called STIS – the Space Telescope Imaging Spectrograph. At the time, it was the most sensitive camera ever flown in space, and I was constantly amazed at what we saw using it.
Hubble did a series of observations called the Deep Fields: it stared at one spot in the sky for days, letting light from incredibly faint objects build up so that they could be detected. For the Deep Field South, STIS was used to observe a particular kind of galaxy, a quasar called J2233-606. The total observation time was over 150,000 seconds – nearly two days!
I worked on these images, and was chatting with a friend about them. We were astonished at the number of objects we could see, distant galaxies so faint that they were unnamed, uncategorized, because no one had ever seen them before. Playing with the numbers, we figured that the faintest objects we could see in the observations had a magnitude of about 31.5. That’s incredibly faint.
How faint, exactly?
The faintest star you can see with just your eye has a magnitude of about 6. Using the magnitude equation I wrote about earlier, plugging those numbers in we get
Brightness ratio = 2.512(31.5 – 6)) = 2.51225.5 = 16 billion
But we can do better than that. A lot better. After all, the Sun is the brightest object in the sky, of course, with a magnitude of -26.7. Just for grins, how much brighter is the Sun than the faintest objects ever seen?
Brightness ratio = 2.512(31.5 – (-26.7)) = 2.51258.2 = 2 x 1023
That’s 200,000,000,000,000,000,000,000. 200 sextillion. Holy yikes.
That number is crushing my mind. It’s ridiculous. A sextillion is simply too big a number to grasp. And 200 of them? C’mon!
But hey, wait a sec…
Does the number 2 x 1023 look familiar to you? It does to me: it’s the same order of magnitude (factor of 10) as Avogadro’s number! It’s the number of atoms of an element in a mole of the element, where a mole is the number of atoms in 12 grams of pure carbon-12. I know, it’s an odd unit, but it’s handy in chemistry, and a lot of (geeky) folks have heard of it.
Avogadro’s number is actually about 6 x 1023. So if we could detect stars or galaxies just a hair more than a magnitude fainter, the ratio of the brightness of the Sun to those objects would be Avogadro’s number. Huh.
I’m not sure that helps, but it’s fun in a spectacularly nerdtastic kind of way.
Science, baby. I love this stuff!
- BAFact Math: Jupiter is big enough to swallow all the rest of the planets whole
- BAFact math: Give him an inch and he’ll take a light year
- BAFact math: how big does the Sun look from Pluto?
- To grasp a billion stars
- Announcing BAFacts: a daily dose of sciencey fun
Earlier this year, the folks at the European Space Agency’s Hubble HQ announced a contest called Hubble’s Hidden Treasures: they wanted people to go through the massive archives of Hubble’s data and look for gorgeous objects that may have been previously overlooked.
This is a cool idea, and they got over 3000 submissions! They just announced the winners, and it’s a collection of jaw-dropping beauty. Here’s the first place winner in the "Image Processing" category, a stunner of NGC 1763, part of a massive star-forming complex in a companion galaxy to our Milky Way:
Oooo, pretty. [Click to embiggen.] That was done by Josh Lake, who won the public vote as well as the judges’ with this work.
Holy wow! You need to click that shot to see it in much higher resolution to really appreciate it. That’s XZ Tauri, a newly-born star a few hundred light years away. XZ Tau is the bright star just to the right of center. In the zoomed shot, you can see two lobes of material on either side of it; these were launched into space during a massive explosive event caught by Hubble back in 2000. The surrounding nebulosity is amazing, too, shaped by shock waves from other new stars which blast off material during paroxysms – young stars rotate rapidly, blow off huge winds, and have strong magnetic fields, which can lead to epic eruptions. They can also blast out beams of material which can travel for dozens of light years.
All the images from the contest are wonderful, and well worth your time to peruse. Funny, too: just yesterday I wrote that digital images from space have revolutionized how we do astronomy, putting the data into the hands of people who can play with it and show us things we hadn’t seen before.
I love it when a plan comes together.
Our Milky Way galaxy is not alone in space. It has several smaller companion galaxies, most notably the Large and Small Magellanic Clouds. Best visible from the southern hemisphere, these two dwarf galaxies may be small in size, but not in content! The LMC in particular has a lot of stuff going on, mostly due to the presence of a vast, sprawling gas cloud nicknamed the Tarantula nebula. The Tarantula is churning out huge numbers of stars, thousands upon thousands, making it a target for astronomers positively drooling to study it.
That includes using Hubble. And when they do, they see beauty like this:
[Click to enarachnidate, or grab the 4000 x 3600 pixel giganticness.]
Isn’t that something? It’s really pretty, but the colors are a bit funny. The nebula is thick with warm hydrogen gas, lit up by the stars embedded in it. In reality this gas glows red, but the filters used to make this image were unusual – they include one that lets through infrared light, which in this picture is colored red. So here the hydrogen has been given a green tint. You can see lots of dark dust strewn about, too. What astronomers call dust is actually more like soot; big molecular chains of carbon that form tiny grains roughly the size of those in cigarette smoke. It’s very thin, but we see through so much of it that the light from stars and glowing gas behind it gets absorbed.
The Tarantula nebula is huge beyond comprehension: it’s 650 light years cross, or nearly 7 quadrillion kilometers (4 quadrillion miles) in size. This image, full of complexity, chaos, and structure down to the smallest scales, represents only about 6% of the entire nebula. I spent quite some time studying this nebula and some of the objects in it – like Supernova 1987A – and it still gives me chills. Space is huge.
By the way, this image was created by Judy Schmidt using archived observations as part of the Hubble’s Hidden Treasures project, to find older, perhaps less well-known pictures, and breathe new life into them. I’d say she did a great job! Go to that link and peruse the others there; trust me, you’ll be glad you did.
Image credit: ESA/Hubble & NASA/Judy Schmidt