Category Archives: Infrared astronomy

alma, astronomy, astronomy research, european southern observatory, Infrared astronomy

Lifting the Veil on the Early Universe

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The Creation of a Galactic Metropolis

An artist’s conception of a giant protocluster of galaxies forming in the early universe. The galaxies are busy forming new stars while at the same time interacting with each other. Courtesy: ESO/M. Kornmesser

From time to time astronomers give us a peek at the early universe and each time they do, they lift the veil on earlier and earlier time periods of our cosmic history. In recent years, they’ve shown us early “shreds” of galaxies and hints of the first stars to ever form. Galaxies began forming some 500 million years after the Big Bang occurred. As galaxies formed through collision and cannibalism, they also clumped together in clusters. One of the oldest clusters is called the Spiderweb Galaxy (or MTC1138-262) is at the heart of a galactic protocluster that began assembling more than 10 billion years ago.

Astronomers interested in star formation in infant galaxies during those early epochs of galaxy building took a closer look at this cluster using the APEX Telescope in Chile, part of the European Southern Observatory. This telescope is exquisitely sensitive to millimeter wavelengths of light (part of the infrared spectrum of light).  It opens a window on distant universe, allowing astronomers to look for faint glimmers of energy from the early universe. They used something called the LABOCA (which stands for Large Bolometer Camera) instrument to look at the cluster. This camera is essentially a sensitive thermometer that helps astronomers sense any kind of heat above absolute zero.  That means it can detect the glimmers of star formation from the early universe, even if they’re hidden by clouds of dust and gas.

Essentially, the APEX telescope and instruments revealed that there are many more sources of star formation in the region of the Spiderweb than astronomers suspected. Their ability to peek behind the veil of dust that hid parts of the cluster’s activity showed astronomers something of a surprise. Yes, star formation is happening there, growing in the interacting galaxies. But, it is  not where they expected it to be. It’s clustered in a relatively small region of the cluster, and not in filaments of gas and dust strung between the member galaxies, where such events usually occur as galaxies interact. Galaxy collisions regularly set off bursts of star formation, and you often see bluish starburst knots strung out between member galaxies like strings of fuzzy pearls.

So, why is star birth so constrained to a smallish, non-central area of the cluster? Good question. Finding the star formation is great news, but now astronomers need to figure out why it’s occurring in a region where they didn’t expect it to be. What processes are shaping the starbirth nurseries in this cluster? Do they tell us something about how clusters formed in the early universe?  Good questions, which astronomers hope to answer by focusing the massed ALMA array on the region when they get a chance. It should give them nicely resolved looks at the stellar creches in the Spiderweb Galaxy and its siblings in the cluster.

 

 

 

astronomy, astronomy research, Helix Nebula, Infrared astronomy, planetary nebulae, star death, stars, stellar evolution

Staring into the Eye of Star Death

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Visiting the Helix

One of the often-asked questions astronomers get is “What will happen when the Sun dies?”  It’s an obvious concern, since whatever happens to the Sun will affect Earth, but it’s not an immediate concern.  The death of the Sun isn’t going to happen for another few billion years yet, so we don’t have to worry about facing it grow larger during its red giant stage and then shrink down to become a tiny ghost of its former brilliance.  Many, many generations of humans will live and die on our planet before future astronomers will start to detect the first instabilities that indicate the Sun’s upcoming demise.

There are stars like the Sun out there in space that have already gone through the death process, and so astronomers study them to understand what our star will look like when it finally gets down to the serious business of stardeath. One of the objects they have studied quite a bit is called the Helix Nebula.

ESO’s VISTA telescope, at the Paranal Observatory in Chile, has captured a striking new image of the Helix Nebula. This picture, taken in infrared light, reveals strands of cold nebular gas that are invisible in images taken in visible light, as well as bringing to light a rich background of stars and galaxies.

The Helix was created as a Sun-like star reached the final stages of its life.  It began to lose its outer layers of gas, which you can see in the image above as they expand into space.  What’s left of the star appears as a tiny blue dot at the center of shell of material surrounding it. That ring spreads out over an area about four light-years across (almost the distance between the Sun and the nearest star in the Alpha Centauri system.  This infrared view shows the extent of the gas cloud.

The nebula is made up of of dust, ionized material and molecular gas. it’s all being heated up by ultraviolet light streaming out from the central star (which is very hot).  Notice the details in the cloud—there are clumpy, comet-shaped objects called cometary knots.  They aren’t really comets, but they look similar to comets with their tails blowing out in the solar wind. In this case, the knots are  strands of molecular hydrogen being shaped by the flow of high-energy radiation streaming out from the dying star. Even though they look small, each is about the size of our solar system.

This, in a nutshell (or a gas shell) is about how our Sun will look billions of years from now. Perhaps our descendants will watch it all unfold from a planet around neighboring star, and take similar pictures with their orbiting space telescopes.

Want to know more about this image. Check out the European Southern Observatory site for more details and an array of downloadable images.