Imagine the planets in our solar system as cookies. Imagine the Sun as a monstrous red-hot cookie monster. Imagine one giant blob of cookie dough flying around and sucking up all of the chocolate chips, nuts and sprinkles in its path. What would a flaming cookie monster do when it sees such a monstrous cookie treat? Num-num-num! According to new research, that’s what happened in the early days of our solar system and may explain why the orbit of Mercury is completely void of any cosmic debris besides the little planet. Num-num-num!
Without the homage to Sesame Street, that’s what Dr. Rebecca Martin, assistant professor in the Department of Physics and Astronomy at the University of Nevada, Las Vegas, describes in her new study, a pre-print version of which was published by the Astrophysical Journal. Martin believes that complete lack of debris around the Sun from its surface to the orbit of Mercury and beyond may be explained by the one-time existence of a super planet that cleared the path, only to be consumed by its own nearby star.
The only [physical] evidence that super-Earths could have formed in our solar system is the lack of anything in that region, not even a rock.
According to Martin's email to Discovery News, the evidence for the existence of this super planet (and possibly more) is the very lack of evidence – namely, space debris – in Mercury’s orbit. While observing other solar systems in early stages of formation, Martin and her team saw that exoplanets which form in orbit (rather than being captured from other stars) grow slowly by absorbing chunks of debris in their path. In time, the debris is gone, the orbit is empty and only a giant dense planet remains.
Using models based on this observation, Martin concluded that a super planet bigger than Earth but smaller than Neptune could have created the void near the Sun early in its life. It would have been formed in the dense cloud of gas and debris that surrounds a new star known as the protoplanetary disc. These zones are turbulent and the debris is magnetically-charged, allowing it to be attracted into what would become a dense planet.
So what happened to Mercury’s big brother, Dr. Martin?
If the disc is sufficiently cool, the migration timescale for them to fall into the Sun is short enough for this to happen in the lifetime of the disc.
In Sesame Street terms, the giant cookie filled with all of the chocolate chips did not cool fast enough to be able to resist the gravity of the solar cookie monster and was eaten, possibly saving its minute friend Mercury (this story is brought to you by the letter M).
Martin (M) says she needs more (M) research than just the models (M) of a monster munching (MM) to confirm this. In the meantime(M), got more (M) cookies?