Phil Plait writes that the evidence suggests some stars have cruised near our sun at surprisingly close distances, and will do so again:
A few years ago, research using Gaia data indicated that the last such close encounter was about 70,000 years ago, when the star WISE J072003.20-084651.2 — also called Scholz’s Star, after the discoverer — passed just 0.8 light-years from the Sun.
But that was then. Every few years the folks with Gaia release updated data from the mission, with newer numbers. This generally improves the accuracy of the motion measurements, because the longer you look at a star the more it moves and the easier that motion is to see. The third such data release occurred in 2022, and a team of astronomers used it to review the data on Scholz’s Star [link to paper].
Things changed with the revised numbers. They found the encounter occurred more like 80,000 years ago, and the distance was more like 1.08 light-years, with a small uncertainty of just 0.026 light-years.
But there's more:
The astronomers then asked, has there been another star that passed even closer with a high degree of statistical confidence?
The answer is yes! They found that the star UCAC4 237-008148 also once swung past the Sun. In this case it passed us at 0.844 ± 0.02 light years about 1.158 million years ago. Even within the uncertainty that’s closer than Scholz’s Star, breaking the record.
I’ll note that today, UCAC4 237-008148 is about 318 light-years away — a million years is a long time for it to move off — and Scholz’s Star is only 22 light years distant.
The astronomers also looked at a third star, HD 7977, about 246 light-years from us now. They found that about 2.77 million years ago it gave us the incredibly close shave of just 0.49 light-years! That’s definitely violating our personal space.
And if humanity can manage to last another million years, it sounds like it won't be too much of a stretch to hop over to this one:
So those are stars that zipped by us in the past. What about the future? The astronomers in this new work didn’t look into that, but with the new Gaia data I imagine that will be done soon. As of now, using older and less-accurate data from the Hipparcos satellite, the next star to come close is Gliese 710, a red dwarf that will slide past us at a hair-raising 0.163 light-years about 1.3 million years from now. I’d love to see how this might change with the new Gaia data.As Plait writes, the problems of close encounters of these types is the danger of them disturbing the Oort cloud enough to send a lot of comets into the inner solar system.
All very interesting.
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