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from the to-clean-up-all-that-dust-you'd-need-a-really-big-vacuum...-Oh?-Wait. dept.
The Atacama Large Millimeter Array (ALMA) has reported the detection of a dust belt around 1-4 astronomical units (AU) from Proxima Centauri, as well as a possible outer belt 30 AU away and an "unknown source" (possible exoplanet) about 1.6 AU away from the star. The data also show "a hint of warmer dust closer to the star".
Proxima b is 0.05 AU from Proxima Centauri, and is considered to be in the star's "habitable zone". The 1-4 AU belt on the other hand has a characteristic temperature of about 40 K, while the 30 AU outer belt would have a temperature of about 10 K. Neptune's moon Triton is roughly 30 AU from the Sun with a temperature of 38 K.
The 1-4 AU belt is estimated to contain 0.01 Earth masses of asteroids (primarily?) up to 50 km in diameter. By comparison, our main asteroid belt (including Ceres) is estimated to contain 4% of the Moon's mass, or about 0.000492 Earth masses (Ceres is about 0.00015 Earth masses, roughly a third of the main asteroid belt). A minimum estimate for the Kuiper belt's mass is 20x that of the main asteroid belt, or the equivalent of this newly detected dust belt around Proxima Centauri.
Astronomy Magazine has an interview with one of the co-authors, who noted another possible exoplanet at 0.5 AU:
There is evidence of an object at half an astronomical unit (AU), but this is very tentative. It's not confirmed, but we committed to putting the data to the public. At this point, there's a signal there, but we're not sure if it's caused by stellar activity or the presence of a planet or something else happening there.
In the dust paper, there seems to be a point source at 1.6 AU. We don't see evidence for anything in the radial velocity there. That doesn't mean there's nothing there, just that the radial velocity is not attuned to an object there, which makes it unlikely that there's a gas giant there.
Also at The Verge and Popular Mechanics.
ALMA Discovery of Dust Belts Around Proxima Centauri (ESO PDF)
Previously: "Earth-Like" Exoplanet Found in Habitable Zone of Proxima Centauri
ESO Confirms Reports of Proxima Centauri Exoplanet
Proxima B Habitability Study Adds Climate Model
An Earth-Like Atmosphere May Not Survive the Radiation in Proxima b's Orbit
(Score: 2) by Thexalon on Tuesday November 07 2017, @10:02PM (3 children)
Breakthrough Starshot is one way we might possibly be able to at least send sensors there that can't communicate with us for another 4-5 years, assuming nothing bad happens between launch and arrival with a 20-30 year travel time.
I'm not saying we shouldn't try for it, just that we're a long way from being able to pull it off, and building spacecraft on paper or computer simulation, difficult as that is, can't hold a candle to how hard it is to build an actual spacecraft and send it off to someplace we've never been and really don't know what we're going to find when we arrive.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 2) by takyon on Tuesday November 07 2017, @11:07PM (2 children)
Keep in mind that the plan is to send hundreds of the chipcraft, not just one. They expect that there could be failures, and I'm not sure they are aiming them very precisely either.
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(Score: 2) by Thexalon on Tuesday November 07 2017, @11:51PM (1 child)
That raises another good point: Guess what happens when you're off by 0.00000001 degrees at these kinds of scales? You miss your target, and likely hit nothing at all.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 3, Interesting) by takyon on Wednesday November 08 2017, @12:05AM
They are unlikely to hit anything in Alpha Centauri period (which would cause them to be destroyed instantly).
Just having these things in the proximity of Alpha Centauri could be a boon to astronomy. Consider what the Hubble or another space telescope would be able to see if it was 100 AU away from Proxima Centauri instead of about 269,000 AU away.
So we also have to ask: what kind of capabilities can we get on a gram-scale chip, and can they transmit the data so that it can be understood from over 4 light years away? The smallest space telescopes [space.com] ever launched have a mass of several kilograms. "Flat" telescopes [soylentnews.org] are possible and will probably get better over the coming decades.
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