Collision of asteroids led to the birth of a planetoidal coarse family 5.8 million years ago
Us astronomers have recently identified 39 planetoids in the asteroid belt, all of which obviously belong to the same family, i.E. Are of the same origin. As the researchers report in the current ie of nature, they managed to back-calculate the orbits of the celestial bodies, date the cosmic catastrophe, and gain plenty of other data along the way. Even a space mission into the asteroid belt seems possible now.
Dora asteroid family. Image: david nesvorny
Actually, asteroids enjoy the attention of most astronomers "optical" fraction of none too coarse popularity. On the one hand, they are difficult to observe in visible light because they reflect only two to four percent of the weak incoming solar radiation and absorb the rest completely. On the other hand, such celestial bodies move much faster than stars and therefore often disfigure long exposed sky photographs with their line-shaped luminous traces.
Chunky asteroid belt
However, the fact is pleasing that most of them are far away from the earth in the asteroid belt, that rock and metal lump-rich zone, in which according to youngest estimations between 1.1 and 1.9 million small planets are supposed to drift. Only rarely it happens that from the asteroid belt embedded between the planets mars and jupiter, which extends in a zone between 300 and 495 million kilometers far away from the sun, some wanderers say goodbye, in order to pay their respects to the earth.
The gurtel, abundantly blessed with planetoids, was formed 4.6 billion years ago at a time when not "all" matter made the leap to planetary self-sufficiency. Instead of being a stately spherical and halfway coarse-grown planet to glamourize its home star, the "residual matter" as a highly unformed and quite small entity again: just as an asteroid.
Vagabond family with 39 members
That this has remained so to this day is due to the enormous gravitational force of the largest planet in our solar system: jupiter influences the asteroids with its gravitational field, throws the small vagabonds out of their orbit and accelerates them, which has the consequence that the planetoids cannot condense into a coarser structure, but rather collide with each other with enormous destructive force and thereby form new asteroid families "asteroid families" consisting of fragments that are chemically identical and in very similar orbits.
Asteroid gaspra: image: nasa
Now, u.S. Scientists from the southwest research institute in boulder, colorado, led by david nesvorny in nature reports that they have spun up such a cosmic family vagabonding in the network, which has 39 members after all.
With an age of "only" 5.8 million years the trummerhaufen consisting of 39 asteroid fragments named karin cluster pays to the youngest so far discovered of its genre. And as it is appropriate for a real family, the rocky clan can even come up with a pair of parents. While the "mother" named 832 karin (hence the name ‘karin cluster’), has a diameter of 19 kilometers, the father 1990 (4507) has a diameter of 14 kilometers.
Unlike the terrestrial representatives of homo sapiens sapiens on mother earth, both astral objects have one and the same mother. According to the researchers’ calculations, they were formed after an approximately three-kilometer-long body with the "mother asteroid" collided, blasted out of the small planet of at least 25 kilometers in size.
Between simulation and extrapolation
In their calculations, the research team (william f. Bottke jr, luke dones harold f. Levison, boulder/colorado), taking into account the gravitation of the four outer giant planets, the development of the orbits in the past. Based on the premise that those objects in the asteroid belt that have a common origin tend to have a related orbit, the researchers were able to use the present orbits of the boulders not only to determine the age of the family, but also to determine that their orbits have changed little since the collision.
But with the data obtained, such as the coarseness of the parent asteroid and the fragments created after the collision, the researchers can extrapolate and visualize via computer the intensity with which rock and stone are shattered during such processes. "This event may teach us about how asteroid material breaks up when an energetic impact and explosion occurs", so nesvorny.
Anders sieht dies bei kollisionen aus, die noch vor viel langerer zeit zur bildung von asteroidenfamilien beigetragen haben. Hier konnen die forscher weder informationen uber die ursprungskorper erhalten noch die verwandtschaft durch spatere kollisionen oder unberechenbare vorkommnisse eindeutig bestimmen. Dies gilt auch fur den fall, dass eine gruppe als mitglieder ein und derselben familie ausgemacht wird.
At least the researchers will be able to study the surface structure of the two rough fragments by means of spectral analysis in the foreseeable future, and in doing so, they will be able to clarify what exactly asteroids are made of and how quickly weathering in space shapes their pockmarked, cratered appearance, and how often asteroids are hit by even smaller colleagues.
In all this the finding is so important, because so far no astronomer succeeded in dating a collision in the asteroid belt so precisely. For derek richardson of the university of maryland, the karin family has become the focus of interest for asteroid researchers. The members of the karin family are therefore "a tempting target for space probes", says team member derek richardson of the university of maryland. "We could study the fresh interior of an asteroid here – like a geologist hitting a boulder with his hammer."