杏吧原创

Around a star about 2300 light years away, something strange is happening. An object is circling the star and blocking out light, but the size and shape of this entity appear to be constantly changing and astronomers don鈥檛 know what it is.

Brian Powell at NASA鈥檚 Goddard Space Flight Center in Maryland and his colleagues spotted an odd pattern in the light from a binary star system called TIC 400799224 using the Transiting Exoplanet Survey Satellite. They found that about once every 19.8 days, something passed between the two stars and the satellite, blocking out starlight.

The dimming was different every time, varying from just a few per cent to about 25 per cent. The length of these eclipses varied too, lasting up to two days 鈥� and sometimes, when 19.8 days had passed and the researchers expected to see another dip in the light, nothing happened.

We have never seen anything quite like this. 鈥淪ometimes the obscuring object is present, sometimes it鈥檚 not, sometimes it鈥檚 a lot larger than other times,鈥� says Powell. 鈥淭hat makes it particularly neat, because we don鈥檛 see that behaviour in planets 鈥� they don鈥檛 just change shape, or disappear sometimes.鈥�

Instead, the researchers suspect that something is regularly emitting huge clouds of dust, which could change shape and dissipate as they orbit one of the stars in the system. To create the observed signals, whatever is creating this must be putting out about 3 million kilograms of dust every second.

If you removed dust from the dwarf planet Ceres at this rate, it would only last for about 8000 years. That may seem like a long time, but in astronomical terms it is extraordinarily quick, making it difficult for a single dust-emitting object to explain the signal.

Instead, Powell says the most likely explanation is that two or more objects are repeatedly crashing together in orbit. 鈥淲e just don鈥檛 have a lot of clarity on what this object is, but it appears there鈥檚 something getting smashed,鈥� he says. Figuring out exactly what is getting pulverised will require more observations over many 19.8-day periods.

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