Astronomers have spotted one of the strangest-looking asteroids we have ever seen. The space rock, called 44 Nysa, was discovered in 1857, but it wasn’t until now that we had the observational capability to figure out its shape – and its shape is weird.
An E-type asteroid, which is a relatively rare type rich in a mineral called enstatite, 44 Nysa circles the sun in the main asteroid belt between the orbits of Mars and Jupiter. It is the brightest E-type asteroid we know of and one of the largest, with an average diameter of about 75 kilometres, which makes it a tempting observational target.
at the Lowell Observatory in Arizona and her colleagues used the Large Binocular Telescope, also in Arizona, and the Very Large Telescope in Chile to take a closer look at 44 Nysa. They used that data to build a three-dimensional model of the asteroid, and found that it seems to have three lobes, each separated from the others by a thin “neck” that holds the asteroid together.
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While two-lobed asteroids are relatively common, trinary ones are much rarer. It isn’t yet clear how exactly it formed – it could have once been a more normal-shaped asteroid and then been battered beyond recognition by other space rocks, or the three lobes could have once been separate and then joined together in what’s called a contact trinary. Either way, its interior must be strong to have stuck together.
Another wrinkle in the story is that 44 Nysa seems to have a tiny moon, just about a kilometre across. In future observations, measuring the moon’s orbit could give us more information about 44 Nysa’s interior structure, and therefore its origins.
arXiv
