Thanks to thawing effect of stellar outburst, ALMA finds building blocks of life
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ALMA has detected the building blocks of life in the disk surrounding a young, distant star. The discovery may help astronomers to understand the origin of life in our own solar system.
Some 3.5 billion years ago, certain molecules teamed up to form the first living organisms on Earth – too small to see without a microscope. The molecules contained atoms of carbon, hydrogen, oxygen, and sometimes nitrogen. Because these molecules are the building blocks of life, they are called ‘organic molecules’, even though they’re not alive themselves.
Astronomers have found organic molecules in comets. Comets are frozen bodies in the outer regions of our solar system. They date back to the very birth of the Sun and the planets. Sometimes, comets can go astray and collide with Earth. That’s why scientists believe that, long ago, comets brought the building blocks of life to our home planet.
New ALMA observations have now revealed organic molecules in the disk surrounding a remote baby star. The disk contains gas and dust. Close to the star, the gas is relatively hot. However, because the star is so far away, ALMA has trouble observing the inner parts of the disk in much detail – they are just too close to the star. As a result, it is hard to detect organic molecules there.
However, at larger distances from the star, it’s not much easier. Here, the temperature is much lower. Most of the organic molecules are frozen onto small dust particles. Frozen molecules do not emit radiation that ALMA can observe. So again, it’s hard to detect these organic molecules.
Luckily, the star is currently experiencing a strong outburst in luminosity. Thanks to the outburst, the temperatures throughout the disk have increased. In the cold, outer parts of the disk, it became hot enough for ice to evaporate. The organic molecules are no longer frozen, so ALMA can study them.
When the outburst stops (probably later this century), temperatures will drop again. The organic molecules will freeze back onto dust particles. In the distant future, these frozen grains will clump together into comets – just like they did in the early days of our own solar system.
The new discovery shows how the building blocks of life can end up in comets. That’s an important part of the story of how life began on Earth. Think of it: without these first organic molecules, you would not be here to read this story!
What?
The young baby star studied by ALMA is known as V883 Orionis. The letter V means that it is a variable star: its brightness and luminosity are changing all the time. V883 Ori is located in a star-forming region some 1,300 light-years away, in the constellation Orion. The star is surrounded by a flat, rotating disk of gas and dust. Due to an ongoing outburst of V883 Ori, ALMA could detect organic molecules in the outer parts of this disk, at a distance of some 9 billion kilometers from the star. One of the organic molecules detected by ALMA is acetone, which people on Earth are using as nail polish remover!
Who?
The ALMA observations of V883 Ori were carried out by an international team of scientists. The team leader was Jeong-Eun Lee, an astronomer at Kyung Hee University in Korea. Jeong-Eun worked together with colleagues from his own institute and from Japan, China, Canada, and Chile. On February 4, 2019, they published the results of their observations in the online scientific magazine Nature Astronomy.
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