Hubble discovers a unique type of object in the Solar System

September 20, 2017, ESA/Hubble Information Centre
This artist's impression shows the binary asteroid 288P, located in the main asteroid belt between the planets Mars and Jupiter. The object is unique as it is a binary asteroid which also behaves like a comet. The comet-like properties are the result of water sublimation, caused by the heat of the Sun. The orbit of the asteroids is marked by a blue ellipse. Credit: ESA/Hubble, L. Calçada.

With the help of the NASA/ESA Hubble Space Telescope, a German-led group of astronomers have observed the intriguing characteristics of an unusual type of object in the asteroid belt between Mars and Jupiter: two asteroids orbiting each other and exhibiting comet-like features, including a bright coma and a long tail. This is the first known binary asteroid also classified as a comet. The research is presented in a paper published in the journal Nature today.

In September 2016, just before the asteroid 288P made its closest approach to the Sun, it was close enough to Earth to allow astronomers a detailed look at it using the NASA/ESA Hubble Space Telescope.

The images of 288P, which is located in the between Mars and Jupiter, revealed that it was actually not a single , but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. That discovery was in itself an important find; because they orbit each other, the masses of the objects in such systems can be measured.

But the observations also revealed ongoing activity in the binary system. "We detected strong indications of the sublimation of water ice due to the increased solar heating—similar to how the tail of a is created," explains Jessica Agarwal (Max Planck Institute for Solar System Research, Germany), the team leader and main author of the research paper. This makes 288P the first known binary asteroid that is also classified as a main-belt comet.

This set of images from the ESA/NASA Hubble Space Telescope reveals two asteroids with comet-like features orbiting each other. These include a bright halo of material, called a coma, and a long tail of dust. The asteroid pair, called 288P, was observed in September 2016 just before the asteroid made its closest approach to the Sun. These images reveal ongoing activity in the binary system. The apparent movement of the tail is a projection effect due to the relative alignment between the Sun, Earth, and 288P changing between observations. The tail orientation is also affected by a change in the particle size. Initially, the tail was pointing towards the direction where comparatively large dust particles (about 1 millimetre in size) were emitted in late July. However, from 20 September 2016 onwards, the tail began to point in the opposite direction from the Sun where small particles (about 10 microns in size) are blown away from the nucleus by radiation pressure. Credit: NASA, ESA, and J. Agarwal (Max Planck Institute for Solar System Research)

Understanding the origin and evolution of main-belt comets—comets that orbit amongst the numerous asteroids between Mars and Jupiter—is a crucial element in our understanding of the formation and evolution of the whole Solar System. Among the questions main-belt comets can help to answer is how water came to Earth. Since only a few objects of this type are known, 288P presents itself as an extremely important system for future studies.

The various features of 288P—wide separation of the two components, near-equal component size, high eccentricity and comet-like activity—also make it unique among the few known wide asteroid binaries in the Solar System. The observed activity of 288P also reveals information about its past, notes Agarwal: "Surface ice cannot survive in the asteroid belt for the age of the Solar System but can be protected for billions of years by a refractory dust mantle, only a few metres thick."

This artist’s impression shows the binary main-belt comet 288P. From a distance the comet-like features of the system can clearly be seen: among them, the bright coma surrounding both components of the system and the long tail of dust and water pointing away from from the Sun. Only a closer look reveals the two components of the system: two asteroids circling each other on an eccentric orbit. Credit: ESA/Hubble, L. Calçada, M. Kornmesser

From this, the team concluded that 288P has existed as a binary system for only about 5000 years. Agarwal elaborates on the formation scenario: "The most probable formation scenario of 288P is a breakup due to fast rotation. After that, the two fragments may have been moved further apart by sublimation torques."

The fact that 288P is so different from all other known binary asteroids raises some questions about whether it is not just a coincidence that it presents such unique properties. As finding 288P included a lot of luck, it is likely to remain the only example of its kind for a long time. "We need more theoretical and observational work, as well as more objects similar to 288P, to find an answer to this question," concludes Agarwal.

Explore further: New theory on origin of the asteroid belt

More information: A binary main belt comet, Nature (2017). , … ic1715/heic1715a.pdf

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5 / 5 (1) Sep 20, 2017
They could have at least used the asteroid spewing water ice from the opening credits of Star Trek Voyager...would have been prettier and about as accurate, even if a bit more spectacular than the real thing. Probably not by a whole lot, depending on the time and position in it's orbit.
1 / 5 (2) Sep 21, 2017
I'm just disappointed, that after expending all that time, effort and funds? They didn't find us any Orion slave girls!
5 / 5 (1) Sep 21, 2017
They could have at least used the asteroid spewing water ice from the opening credits of Star Trek Voyager...would have been prettier and about as accurate, even if a bit more spectacular than the real thing. Probably not by a whole lot, depending on the time and position in it's orbit.

I believe that was DS9. Lord I'm a nerd.
not rated yet Sep 22, 2017
I wonder if Nanosatellites.could be used, in the future, as inexpensive relay points that could be strung out towards the asteroid belt...
1 / 5 (1) Sep 22, 2017
Hee hee the bible says that strange things will be seen in the sky in the last days. Can't wait to see what is next.
1 / 5 (2) Sep 23, 2017
We'll Know this is "The End of Days" when we see these strange sights here on Earth....

An honest evangelist preacher

A self-proclaimed believer who can utter a coherent sentence rather than holy gibberish

A prayer uttered that wasn't a self-serving demand for unearned wealth and power.

Please, feel free to add to this list....
1 / 5 (2) Sep 24, 2017
Damn it all to hellngone! I slept through the latest rapture one more time. Missing my chariot ride to heaven....

Since you are reading this, now, the day after 'The Day'. I'm guessing your stuck here also? Is this anyway to run a railroad?
not rated yet Sep 26, 2017
as I have emailed NASA, ESA and DLR ON Rosetta encounter with comet 67p GC and told them they do not know structure of space bodies and gave them some information. they were not mature to ask officially for full detail. here is yet another confirmation they do no know much about space bodies. This is as interesting as anthropologist present their finding that they have discovered some Papua new guinea couple some times break wind. congratulation astronomer. may be one day you progress sufficiently to ask officially for space information so you can spend your time and resources to discover useful information instead of discovering a wheel which is round. full detail in my 1975 Bremen summerhouse notes or on official request only. MG1

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