NASA’s Hubble Space Telescope has been used to spy a ring of dusty debris around a distant star, giving us an insight into planet formation.
The star, which is about 240 light-years away, is called HR 4796 A, and it’s just 8 million years old; our Sun, for comparison, is 4.6 billion years old. It’s in a binary system with another nearby star, a red dwarf called HR 4796 B, 87 billion kilometers (54 billion miles) away.
We’ve seen the younger star and its dusty ring before. But Hubble’s new images have given us a fresh look, revealing some unusual things that we hadn’t spotted before. It also gives us a look at what’s surrounding the star. A paper describing the findings is published in The Astronomical Journal.
The ring of debris extends about 11 billion kilometers (7 billion miles) from the star, which is almost twice the distance that Pluto orbits our Sun. It’s been pushed out by the pressure of starlight from the star, which is 23 times more luminous than our own Sun.
In this Hubble image, we can also see how the larger amount of dust around the bright inner debris ring is shaped. It’s thought that the bright inner ring around the star may be being shaped by a planet that has already formed.
The larger dust around the star is much more extended in one direction (towards the top of the image) than the other. This could be a result of the gravity from its red dwarf companion, or it could be a result of the star’s movement through interstellar space, like a bow wave from a boat.
“Environmental effects, such as interactions with the interstellar medium and forces due to stellar companions, may have long-term implications for the evolution of such systems,” Glenn Schneider from the University of Arizona, Tucson, the lead author on the study, said in a statement.
“The gross asymmetries of the outer dust field are telling us there are a lot of forces in play that are moving the material around.”
Studying stars like this is important because it tells us a bit about how planets form in these dusty disks – including our own Solar System. They’re thought to be common around stars, with about 40 seen so far. But the more the better.
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