Tag: Hubble Ultra Deep Field

Another record breaker: ultra-deep image reveals ultra-distant galaxy

By Phil Plait | January 26, 2011 11:03 am

Astronomers have just announced they have discovered what may be the most distant galaxy ever seen, smashing the previous record holder. This galaxy is at a mind-crushing distance of 13.2 billion light years from Earth, making it not just the most distant galaxy but also the most distant extant object ever detected!

Here is the object in question:

The small box shows the location of the galaxy, which is invisible by eye in the image. The zoomed region shows it in the infrared, where it glows more strongly.

[NOTE: Let me be clear up front and say that this is a candidate galaxy, since it hasn’t been confirmed using other distance determination methods. However, having read the paper I think the astronomers did an excellent job showing this is very likely to be a galaxy 13.2 giga-light years away. From here on out I’ll refer to it as if it’s real, but to be fair bear in mind there is some small chance it may turn out not to be real.]

Named UDFj-39546284, the galaxy is seen as it was just 480 million years after the Universe itself formed! The previous record holder — which was announced just last October — was 13.1 billion light years away. This new galaxy beats that by 120 million light years, a substantial amount. Mind you, these galaxies formed not long after the Big Bang, which happened 13.73 billion years ago. We think the very first galaxies started forming 200 – 300 million years after the Bang; if that’s correct then we won’t see any galaxies more than about 13.5 billion light years away. Going from 13.1 to 13.2 billion light years represents a big jump closer to that ultimate limit!

The galaxy was found in the infrared Hubble Ultra Deep Field, or HUDF, an incredible observation where Hubble pointed at one patch of sky and stared at it for 173,000 seconds: 48 solid hours! After Hubble’s Wide Field Camera 3 observed it, this supposedly blank patch of sky came alive with thousands upon thousands of distant galaxies, and in fact the last record-breaking galaxy was found in the image. The picture here shows the whole HUDF image, with the first picture at the top of this post outlined. Click it to see it in full size, and you’ll start to get an appreciation of just how freaking tough these observations are. The sky is full of faint galaxies!

This new discovery was found using what’s called the dropout technique. Read More

CATEGORIZED UNDER: Astronomy, Cool stuff

Hubble digs deep to see baby galaxies

By Phil Plait | December 8, 2009 9:17 am

I haven’t heard much from the Hubble Space Telescope folks since it was refurbished earlier in the year. Maybe that’s because they’ve been busily working on putting together an incredible image, the deepest ever taken in the near infrared. Feast upon this:


[Oh yes, you want to click to embiggen that, or grab yourself a gorgeous
4.6 Mpixel version.]

Holy Haleakala! This picture is incredible. They pointed Hubble at a fairly empty region of space, one where very few stars are seen. Then they unleashed the new Wide Field Camera 3 (called WFC3 for short) on it, taking images in infrared wavelengths just outside what the human eye can see… and they let it stare at that spot for a solid 48 hours.

The result? This picture, showing galaxies flippin’ everywhere, some seen a mere 600 million years after the Big Bang itself. Because the Universe is expanding, distant galaxies appear to recede from us, and their light gets stretched out. This Doppler Effect — the same thing that makes the sound of a car engine drop in pitch when it passes you at high speed — changes the colors we see from these far-flung galaxies, so their ultraviolet light, for example, gets stretched into visible and even infrared wavelengths. What you are seeing here is actually more energetic light emitted by galaxies that’s lost energy traveling across the expanding Universe, so by the time it gets here it’s infrared.

So the colors are not "real" in this image; they’ve been translated into red, green, and blue so we can see them. The reddest objects in the image are most likely the farthest away, and may be as much as 13 billion light years away.

Thirteen billion. With a B.

hudf_wf3_detailLet me point out something: here is a zoom in on one part of this ultra deep field, from the upper left. I’ve marked three objects. The one in the middle is a star; even with Hubble stars are point-like sources. The light from the star gets bent a bit (diffracted) around the metal support structure holding one of Hubble’s mirrors in place, giving it that crosshairs feature (we astronomers in the know call them diffraction spikes).

But look, the object on the left, clearly a galaxy, has crosshairs too! And they’re centered right on the galaxy’s nucleus, meaning that galaxy has a very bright, star-like core. We see this a lot in galaxies, when the supermassive black hole that lurks at the heart of every galaxy happens to be actively and voraciously eating matter. As this material spirals in, it gets very, very hot, and emits vast amounts of light. We call these active galaxies, and they were common in the early Universe. Studying them gives us insight into what galaxies were like when they were young, how that monster black hole forms and changes over time, and how galaxies themselves are born, age, and evolve over time. How many active galaxies can you find in the bigger picture?

And that little red dot all the way on the right? It’s not possible to say for sure, but given its reddish color in the picture and the fact that it’s a tiny dot makes me think this is one of those extremely distant galaxies, an object whose light has been traveling for roughly 95% of the age of the Universe itself. Those photons have hiked for billions of light years, seen the Universe change drastically, slammed through dust and gas clouds, curved around gravitationally-warped space, all to finally fall into the waiting glass mirror of our eyes’ orbiting proxy in space.

And there are dozens of those red dots in this image, all full galaxies in their own right, shrunk in apparent size and stature by their mind-numbing distance. And there are thousands of other galaxies, too… and yet this image is small, covering an area of the sky only 1/15th the width of the full Moon — it would take 8000 30 million images like this to cover the whole sky!

That means that everywhere you look, any direction you may choose, there are thousands, millions, billions of galaxies lurking there, hidden by nearby stars, gas, dust, other galaxies, and the terrible scale of space and time of our ancient Universe.

Everywhere we look, there are treasures to unveil. That’s what science tells us. And that’s why I love it.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

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