Post by Andrei Tchentchik on Jun 26, 2019 18:33:22 GMT 2
(.#227).- An underground asteroid turns upside down in our Solar System.
An underground asteroid turns upside down in our Solar System.
By Tristan Vey - Posted on 23/05/2018 at 12:42
Unlike "trojan" asteroids that rotate with Jupiter around the Sun in the same direction, 2015 BZ 509 turns in the opposite direction ... NASA / JPL-Caltech.
Discovered in 2014, the asteroid 2015 BZ 509 shares roughly the same orbit as Jupiter, but turns in the opposite direction. Astronomers think today that it was captured to a nearby star in the early youth of our Sun.
Last October, an asteroid from elsewhere, 1I / 2017 U1 ('Oumuamua), made a fleeting incursion into our Solar System before returning to the depths of outer space. It was the first time that the passage of a foreign body in our neighborhood was recorded by astronomers. We are in a situation a little different this time: astronomers think that our star has snatched in his early youth an asteroid to a neighbor. This kind of cosmic stowaway would have accompanied us forever, according to a new study published Monday in the Monthly Notices of the Royal Astronomical Society.
This is the strange orbit of this 3km body, discovered in 2014 by the Pan-STARRS automatic detection program, in Hawaii, which put the bug in the ears of researchers. For starters, 2015 BZ 509 turns upside down around the Sun. It's not common. There are less than a hundred of these objects called "retrograde" in the Solar System, less than 0.01%. But that's not all. Most of them are usually in very elliptical orbits. This is not the case of "BZ": its orbit is relatively little stretched. Its average distance to the Sun is finally the same as the planet Jupiter and its identical period of revolution: 11.6 years. Whenever Jupiter takes a turn around the Sun in one direction, "BZ" makes a turn in the other direction.
"Unlike the other retrograde objects that struggle to stay more than 10,000 years in their orbits in the models, 2015 BZ 509 remained there without problem 100 times longer," says Fathi Namouni, astronomer at the Observatory of the Côte d'Azur, first author of these new works. "So we extended our calculations." With his colleague Helena Morais, Unesp, Brazil, the researcher used a new model, more accurate, and monumental computing to trace the history of this asteroid on billions years.
Result: The orbit of "BZ" is surprisingly stable. "We can go back to the origins of the Solar System without any problem. But at that time, all objects turned in the same direction, without exception. That can only mean one thing: this asteroid does not come from here. "This would make it the first" captive "foreign body in our Solar System. The models also show that asteroids captured at the same time could tend to have their orbits gradually shift to end up on trajectories perpendicular to the Solar System plane. "We are looking to see if the bodies we know about these polar orbits could have an extrasolar origin," says Fathi Namouni.
The Sun no longer takes passengers
Could the other known retrograde objects also be "clandestine"? "A priori, no. These are usually objects that come from the Oort cloud, a vast reservoir of icy bodies located 10,000 times farther from the Sun than the Earth (for comparison, Pluto never distances Earth's distance more than 50 times Soleil, Ed), "says the researcher. In these very remote areas, the gravity exerted by the Sun competes with that produced by the 100 billion stars that make up our galaxy, the Milky Way.
This galactic tidal effect gradually moves the plane in which these objects revolve around the Sun. After a few million years, they are turned over like pancakes and then turn in the wrong direction. If they are disturbed at this moment, they can be projected towards the interior of the solar system, like Halley's comet, which periodically returns to illuminate the sky every 76 years (next passage in 2061).
Could our Sun still take passengers from elsewhere? "No, it's almost impossible," says Fathi Namouni. "In its early youth, the Sun had not only neighbors, but the Solar System was still bathed in a cloud of gas that could curb these foreign objects to keep them in orbit. Without this gas, the asteroids that cross our path can not stop and are condemned to be ejected. "
F I N .
An underground asteroid turns upside down in our Solar System.
By Tristan Vey - Posted on 23/05/2018 at 12:42
Unlike "trojan" asteroids that rotate with Jupiter around the Sun in the same direction, 2015 BZ 509 turns in the opposite direction ... NASA / JPL-Caltech.
Discovered in 2014, the asteroid 2015 BZ 509 shares roughly the same orbit as Jupiter, but turns in the opposite direction. Astronomers think today that it was captured to a nearby star in the early youth of our Sun.
Last October, an asteroid from elsewhere, 1I / 2017 U1 ('Oumuamua), made a fleeting incursion into our Solar System before returning to the depths of outer space. It was the first time that the passage of a foreign body in our neighborhood was recorded by astronomers. We are in a situation a little different this time: astronomers think that our star has snatched in his early youth an asteroid to a neighbor. This kind of cosmic stowaway would have accompanied us forever, according to a new study published Monday in the Monthly Notices of the Royal Astronomical Society.
This is the strange orbit of this 3km body, discovered in 2014 by the Pan-STARRS automatic detection program, in Hawaii, which put the bug in the ears of researchers. For starters, 2015 BZ 509 turns upside down around the Sun. It's not common. There are less than a hundred of these objects called "retrograde" in the Solar System, less than 0.01%. But that's not all. Most of them are usually in very elliptical orbits. This is not the case of "BZ": its orbit is relatively little stretched. Its average distance to the Sun is finally the same as the planet Jupiter and its identical period of revolution: 11.6 years. Whenever Jupiter takes a turn around the Sun in one direction, "BZ" makes a turn in the other direction.
"Unlike the other retrograde objects that struggle to stay more than 10,000 years in their orbits in the models, 2015 BZ 509 remained there without problem 100 times longer," says Fathi Namouni, astronomer at the Observatory of the Côte d'Azur, first author of these new works. "So we extended our calculations." With his colleague Helena Morais, Unesp, Brazil, the researcher used a new model, more accurate, and monumental computing to trace the history of this asteroid on billions years.
Result: The orbit of "BZ" is surprisingly stable. "We can go back to the origins of the Solar System without any problem. But at that time, all objects turned in the same direction, without exception. That can only mean one thing: this asteroid does not come from here. "This would make it the first" captive "foreign body in our Solar System. The models also show that asteroids captured at the same time could tend to have their orbits gradually shift to end up on trajectories perpendicular to the Solar System plane. "We are looking to see if the bodies we know about these polar orbits could have an extrasolar origin," says Fathi Namouni.
The Sun no longer takes passengers
Could the other known retrograde objects also be "clandestine"? "A priori, no. These are usually objects that come from the Oort cloud, a vast reservoir of icy bodies located 10,000 times farther from the Sun than the Earth (for comparison, Pluto never distances Earth's distance more than 50 times Soleil, Ed), "says the researcher. In these very remote areas, the gravity exerted by the Sun competes with that produced by the 100 billion stars that make up our galaxy, the Milky Way.
This galactic tidal effect gradually moves the plane in which these objects revolve around the Sun. After a few million years, they are turned over like pancakes and then turn in the wrong direction. If they are disturbed at this moment, they can be projected towards the interior of the solar system, like Halley's comet, which periodically returns to illuminate the sky every 76 years (next passage in 2061).
Could our Sun still take passengers from elsewhere? "No, it's almost impossible," says Fathi Namouni. "In its early youth, the Sun had not only neighbors, but the Solar System was still bathed in a cloud of gas that could curb these foreign objects to keep them in orbit. Without this gas, the asteroids that cross our path can not stop and are condemned to be ejected. "
F I N .
