Proxima Centauri's Unprecedented Passage

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Proxima's Unprecedented Passage: When Stars Align

by Dr. Ken Croswell

Of the hundreds of billions of stars that throng the Milky Way, only one is closest to the Sun: a little red dwarf named Proxima Centauri, a star so dim it was unknown a century ago. Now this stellar neighbor is about to betray some of its secrets, because in October it will pass in front of another star. As the light from the distant star skirts past Proxima, the red star's gravity will bend the beam, divulging our neighbor's mass and perhaps even its planets.

Full story at Scientific American.
 

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Simon Bridge
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What's unprecedented? gravitational shifting? stars lining up? ... but perhaps that's just an attention-grabbing headline and I shouldn't take it at face value? <reads>
A gravitational deflection by a star "has never ever been seen outside of the solar system," says astronomer Kailash Sahu of the Space Telescope Science Institute, ...
Isn't he talking about effects associated with gravitational micro-lensing?
Compare: http://hubblesite.org/newscenter/archive/releases/2013/22/full/
The stars will shift very slightly in their apparent position, an estimated 0.5 milliarcsecond and 1.5 milliarcseconds, respectively. ... These so-called microlensing events will last from a few hours to a few days.
... I thought these were routinely "seen outside of the solar system" these days? Possibly he meant to be more specific than was reported?

Of course - technically, this event won't be seen outside the solar system anyway: the telescopes, where it will be seen, are on (and in orbit around) the Earth.

This is probably nit-picky but I do get this cringe about science journalism ... I think the Hubble Site release does a better job of describing what's cool about the anticipated set of events.

I see you've enjoyed posting segments from magazine articles twice before, but you never comment on them yourself (not in the first instance anyway) - why not? Did you have a question about the article? Perhaps you wanted to start a discussion? Perhaps it's apropos of nothing? Give us a hint please.

You'll find people more forthcoming with their ideas if you start out by sharing your own first.
 
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There are at least two unprecedented aspects of Proxima Centauri's alignments.

1. Never before has a star other than the Sun been seen to shift the apparent position of a star behind it. The previous cases of microlensing involve an unseen star ampliflying the brightness of a star behind it.

2. Never before have we directly measured the mass of an isolated star other than the Sun. Normally stars have to be orbiting close to each other in order for us to measure their mass directly. Proxima Centauri is so far from Alpha Centauri A and B that the only mass determinations are estimates based on its low luminosity. These new observations should yield Proxima's mass to an accuracy of 5 percent.

It's especially nice that we'll be gaining this information about a member of the nearest star system to the Sun.

Unlike the press release, the Scientific American article

1. Quotes an outside expert for his perspective.

2. Gives the probability--it's low--that these alignments will actually reveal planets around Proxima.
 

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