'Zoo' of potentially planet-forming discs around new stars captured by telescope
'Like the sun, but when the sun was very, very young,' researcher says
It's almost like looking at baby pictures.
Astronomers at the European Southern Observatory in Chile have photographed regions around young stars — they call it a "zoo" — that may be what our solar system looked like as an infant.
These images will help further our understanding on how planets form and even how we have come to be, in ways astronomers haven't been able to do.
"Essentially we are looking at something that is like the sun, but when the sun was very, very young," Henning Avenhaus, lead author of the paper published in Astrophysical Journal this week, told CBC News.
"Obviously we can't go back in time and look at what the solar system looked like 4.5 billion years ago … so instead, we have to look at stars that are similar to the sun but much younger."
Roughly 4.5 billion years ago, dust and gas in our region of space received a sort of kick — perhaps by the death and explosion of a nearby star — that caused them to merge and collapse under their own gravity. Eventually, fusion began, with hydrogen converting to helium. The sun was born.
But not all the material was used in the new star's formation. For a short time — astronomically speaking, at least — the remaining material circled the star, perhaps for a few million years. Eventually, that material also coalesced, forming the planets we know today, including Earth.
Though astronomers have a relatively solid grasp on how our solar system formed, the process on a galactic or even universal scale is poorly understood.
Thirty years ago, astronomers believed some stars might have planets orbiting them. Today it's known that most stars have their own planets, varying from what scientists label large "super-Earths" to the size of Jupiter. They orbit their stars closer than Mercury orbits the sun.
The challenges
Most of these new star-forming regions exist somewhat close to Earth, again, on a cosmological scale, just 300 to 550 light-years away (our galaxy spans 100,000 light years).
But photographing these regions is no easy task. They can't be seen with the naked eye, and even with telescopes it's tricky.
Astronomers measure small areas in the sky using arc minutes and arc seconds, among other means. The moon, for example, is 1,800 arc seconds in diameter. These newly formed areas measure just one to five arc seconds.
And it gets even more challenging: astronomers also have to block out the light of the distant stars, which can measure just 0.0001 arc seconds.
So the team of researchers used an instrument on the observatory's Very Large Telescope called the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument, or the much-easier-to-remember SPHERE. This instrument blocks out such small regions of light and directly observes these new star-forming regions.
Diversity in the making
What's particularly interesting — and potentially revealing — is the variety of these planet-forming regions, or protoplanetary discs.
Some are quite large. Some contain bright rings, some dark rings. And some look like yo-yos or hamburgers.
While these hamburgers may make it appear as though there could be two separate regions where planets may form, that's not quite the case. Instead, that dark part is in shadow, and is, in fact, the densest part, the plane where the planets will eventually form.
These new images and their differences provide astronomers with insight into the diverse planets we've seen orbiting other stars.
"We know the process must be super chaotic, because the outcome is chaotic," Avenhaus said.
Next, the researchers hope to find more of these regions, to provide them with a larger sample size.
"The more we look at, the more we can hopefully understand what is really going on," Avenhaus said.
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