Our Solar System's First Known Interstellar Object Gets Unexpected Speed Boost
Release date: Jun 27, 2018 1:00 PM (EDT)
A mysterious interstellar interloper that made a fast detour through our solar system last October has defied labels. Astronomers can't figure out whether it's an icy comet or a rocky asteroid. Maybe the object, dubbed `Oumuamua (oh-MOO-ah-MOO-ah), is a new class of object because it hails from another star system untold light-years away.
`Oumuamua dove right towards the Sun and now is zipping out of the solar system and back into interstellar space. The wayward vagabond is blazing along so fast that telescopes, including Hubble, have captured only fleeting glances of it. But after analyzing data of `Oumuamua, astronomers now have evidence that the object is behaving more like a comet than an asteroid.
The observations show that the object is undergoing a slight acceleration since its discovery in October 2017. This mysterious and unexpected acceleration is not due to any gravitational pulling from solar system bodies, the researchers say.
One possibility is that the object is venting material off its surface — like a comet — which is causing the acceleration. This outgassing pushes `Oumuamua along as it barrels out of the solar system. Such hypothesized outgassing is not directly visible in any observations. It is likely that heat from the Sun is causing ices to sublimate away from the object, pushing it in the opposite direction.
This conclusion suggests that perhaps low-mass cometary bodies are ejected from other star systems and wander the Milky Way galaxy for millions or billions of years.
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