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
Related Stories
Astronomers have reportedly discovered an Earth-like exoplanet in the habitable zone of Proxima Centauri, one of the closest stars to our Sun. However, the claim is based on an anonymous source who is said to have leaked the news ahead of an announcement by the European Southern Observatory:
[In] what may prove to be the most exciting find to date, the German weekly Der Spiegel [translation] announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within it's sun's habitable zone, and is within our reach. But is this too good to be true? [...] Citing anonymous sources, the magazine stated:
The still nameless planet is believed to be Earth-like and orbits at a distance to Proxima Centauri that could allow it to have liquid water on its surface — an important requirement for the emergence of life. Never before have scientists discovered a second Earth that is so close by.
In addition, they claim that the discovery was made by the European Southern Observatory (ESO) using the La Silla Observatory's reflecting telescope. Coincidentally, it was this same observatory that announced the discovery of Alpha Centauri Bb back in 2012, which was also declared to be "the closest exoplanet to Earth". Unfortunately, subsequent analysis cast doubt on its existence, claiming it was a spurious artifact of the data analysis.
However, according to Der Spiegel's unnamed source – whom they claim was involved with the La Silla team that made the find – this latest discovery is the real deal, and was the result of intensive work. "Finding small celestial bodies is a lot of hard work," the source was quoted as saying. "We were moving at the technically feasible limit of measurement." The article goes on to state that the European Southern Observatory (ESO) will be announcing the finding at the end of August. But according to numerous sources, in response to a request for comment by AFP, ESO spokesman Richard Hook refused to confirm or deny the discovery of an exoplanet around Proxima Centauri.
[Continues...]
Last week, news of the discovery of a potentially habitable "Earth-like" exoplanet orbiting the nearest star to our Sun (Proxima Centauri) leaked to Der Spiegel. Today, the European Southern Observatory confirmed the news about Proxima b:
Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us — and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.
[...] At times Proxima Centauri is approaching Earth at about 5 kilometres per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.
A note on the press release discusses the potential habitability of Proxima b, given that it is orbiting close to a red dwarf star:
[Continues...]
[N]ew models increasingly suggest that the closest Earth-like planet to our solar system could be habitable. Researchers first started playing a bit of "fantasy exoplanet" with the rocky world—dubbed Proxima b—last year after scientists discovered it orbiting our nearest neighbor star, Proxima Centauri. With knowledge only of the luminosity of the star (1/600 that of the sun), the mass of the planet (1.3 times that of Earth), and the length of its orbit (11.2 days), the team was able to predict that, with a variety of possible atmospheres, it would be possible for Proxima b to harbor liquid water on its surface.
Now, another team has upped the level of detail by taking a climate model designed for Earth—the Unified Model developed by the United Kingdom's Met Office—and pasted it onto Proxima b.
[...] As the team reports today in Astronomy & Astrophysics, it found an even wider range of circumstances in which Proxima b could have liquid water than the earlier study. The fact that the two very different models agree so closely is "somewhat remarkable," the team writes.
Source: Daniel Clery at sciencemag.org
Another study has cast doubt on the habitability of an Earth-like exoplanet in the "habitable zone" of a red dwarf, in this case Proxima Centauri specifically:
At only four light-years away, Proxima b is our closest known extra-solar neighbor. However, due to the fact that it hasn't been seen crossing in front of its host star, the exoplanet eludes the usual method for learning about its atmosphere. Instead, scientists must rely on models to understand whether the exoplanet is habitable.
One such computer model considered what would happen if Earth orbited Proxima Centauri, our nearest stellar neighbor and Proxima b's host star, at the same orbit as Proxima b. The NASA study, published on July 24, 2017, in The Astrophysical Journal Letters [DOI: 10.3847/2041-8213/aa7eca], suggests Earth's atmosphere wouldn't survive in close proximity to the violent red dwarf.
[...] In Proxima Centauri's habitable zone, Proxima b encounters bouts of extreme ultraviolet radiation hundreds of times greater than Earth does from the sun. That radiation generates enough energy to strip away not just the lightest molecules — hydrogen — but also, over time, heavier elements such as oxygen and nitrogen.
The model shows Proxima Centauri's powerful radiation drains the Earth-like atmosphere as much as 10,000 times faster than what happens at Earth.
Previously: "Earth-Like" Exoplanet Found in Habitable Zone of Proxima Centauri
Proxima b May Have Oceans
Researchers Suffocate Hopes of Life Support in Red Dwarf "Habitable Zones"
Proxima B Habitability Study Adds Climate Model
Related: MAVEN Results Find Solar Wind and Radiation Responsible for Stripping the Martian Atmosphere
Proxima Centauri b confirmed as nearest exoworld
Four years ago, scientists made one of the most exciting exoplanet discoveries so far, a rocky planet similar in size to Earth orbiting the nearest star to the sun, Proxima Centauri. While the detection seemed solid, more confirmation is always good, and now the ESPRESSO spectrograph on the Very Large Telescope (VLT) in Chile has provided that extra and more detailed confirmation. The news was announced by the University of Geneva (UNIGE) on May 28, 2020.
[...] Proxima Centauri b is very similar in size to Earth, with a mass of 1.17 Earth masses. It orbits its star in only 11.2 days, in contrast to our Earth's year-long orbit around our sun. That means Proxima Centauri b is a lot closer to its star than Earth is to the sun. But, because the star is a red dwarf – much smaller and cooler than our sun – its orbit is indeed within the habitable zone of Proxima Centauri. Interestingly, Proxima Centauri b receives about the same amount of solar energy from its star that Earth does from our sun.
[...] The mass of Proxima b was previously estimated to be 1.3 Earth masses. The accuracy of the new measurement of 1.17 Earth masses is unprecedented, according to Michel Mayor, the "architect" of all ESPRESSO-type instruments:
ESPRESSO has made it possible to measure the mass of the planet with a precision of over one-tenth of the mass of Earth. It's completely unheard of.
The new confirmation of Proxima Centauri b is exciting, but there may be more surprises in store ... there is also possible evidence of another and smaller planet in the newest data. A secondary detection was also made, although it isn't certain whether it is actually a planet. If it is, it is even smaller than Proxima Centauri b. [...] If it is a planet, it would be more akin to Mars or Mercury in size and mass – estimated at a minimum Earth mass of 0.29 ± 0.08 – and orbits the star in only 5.15 days. It wouldn't be too surprising, though, in that low-mass stars like red dwarfs tend to have multiple planets in their systems. More observations will be required to either confirm or refute this possible second planet.
Journal Reference
Mascareño, A. Suárez, Faria, J. P., Figueira, P., et al. Revisiting Proxima with ESPRESSO, (https://arxiv.org/abs/2005.12114v1)
Proxima Centauri - Planetary system
Previously: ESO Confirms Reports of Proxima Centauri Exoplanet
Proxima b May Have Oceans
Dust Belts and Possible Additional Exoplanet Spotted Around Proxima Centauri
First Light for VLT's ESPRESSO Exoplanet Hunter
Very Large Telescope's ESPRESSO Combines Light From All Four Unit Telescopes for the First Time
Proxima Centauri's No Good, Very Bad Day
High Levels of Ultraviolet Radiation Should Not Preclude Life on Exoplanets
Icy second planet potentially spotted orbiting Proxima Centauri
Earth-like planet spotted orbiting Sun's closest star
Astronomers have discovered a third planet orbiting Proxima Centauri, the star closest to the Sun. Dubbed Proxima Centauri d, the newly spotted world is probably a bit smaller than Earth, and well within the habitable zone of its host star — meaning that it could have oceans of liquid water that can potentially harbour life.
"It's showing that the nearest star probably has a very rich planetary system," says Guillem Anglada-Escudé, an astronomer at the Institute for Space Sciences in Barcelona, Spain, who led the team that in 2016 discovered the first planet to be seen orbiting Proxima Centauri.
Astronomer João Faria and his collaborators detected Proxima Centauri d by measuring tiny shifts in the spectrum of the star's light as the planet's gravity pulled it during orbit. The team used a state-of-the art spectrograph called ESPRESSO at the Very Large Telescope, a system of four 8.2-metre telescopes at the European Southern Observatory in Cerro Paranal, Chile. The results were published on 10 February in Astronomy & Astrophysics.
A candidate short-period sub-Earth orbiting Proxima Centauri
We detect a signal at 5.12 ± 0.04 days with a semi-amplitude of 39 ± 7 cm s−1. The analysis of subsets of the ESPRESSO data, the activity indicators, and chromatic RVs suggest that this signal is not caused by stellar variability but instead by a planetary companion with a minimum mass of 0.26 ± 0.05 M⊕ (about twice the mass of Mars) orbiting at 0.029 au from the star. The orbital eccentricity is well constrained and compatible with a circular orbit.
Previously: "Earth-Like" Exoplanet Found in Habitable Zone of Proxima Centauri
ESO Confirms Reports of Proxima Centauri Exoplanet
Dust Belts and Possible Additional Exoplanet Spotted Around Proxima Centauri
Icy second planet potentially spotted orbiting Proxima Centauri
Proxima Centauri b Confirmed Using VLT's ESPRESSO, Possible Third Exoplanet Found in System
(Score: 0) by Anonymous Coward on Tuesday November 07 2017, @05:24PM
Is that like a metric ton?
(Score: 3, Insightful) by bob_super on Tuesday November 07 2017, @07:25PM (9 children)
Cruising the universe is like a drive west of the Mississippi: There's occasionally some really cool stuff, and seemingly endless boredom in between those places.
(Score: 3, Informative) by Thexalon on Tuesday November 07 2017, @07:58PM (7 children)
Plus we're cruising at a simply pathetic speed right now. The fastest we've ever managed (and this was with some gravity assists) is 0.000134c (approximately 33,000 m/s). So it's not just traversing Kansas, it's traversing Kansas at a speed of approximately 24 millimeters per hour, or about 1/10 the speed of a typical single-celled organism.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 3, Informative) by takyon on Tuesday November 07 2017, @09:29PM (6 children)
The Alpha Centauri system will get closer to us over the next roughly 27,700 years. So that's about how long we have to figure out how to travel there. It will be slightly easier in 1000 years. Breakthrough Starshot [wikipedia.org] is one way we could at least send sensors there with a 20-30 year travel time.
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(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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(Score: 2) by jmorris on Wednesday November 08 2017, @12:35AM (1 child)
Just launching them requires some serious unobtainium but I'm utterly unconvinced we would ever be able to pull a signal from such weak sources out of the noise at interstellar distances even with a base on the far side of the moon. Building a 100GW phased array of lasers able to compensate for atmospherics is one thing, inventing new physics to get a signal back that has disappeared in the background noise of the universe is something else entirely.
Read it carefully. They are saying that for 10-15 billion we could experiment with one by 2036, NOT that we could launch anything at another star. I'd want to see a dozen launched at more obtainable speeds out to a comet beyond Neptune and see that we can actually observe the signal and then see if there is enough S/N to copy data at a usable speed. Remember how long it took to download the Pluto data? That probe had a fairly hefty transmitter and antenna, not a few grams of total mass. Now they want a thousand little ones all transmitting at once and all so close together from our viewpoint that no conceivable antenna can discriminate them.
(Score: 2) by takyon on Wednesday November 08 2017, @12:55AM
They are in the R&D phase obviously (since no test before 2036 and that is just their current timeline), so if it is impossible I expect them to let us know within the next 5-10 years.
I have heard of two approaches to getting the data back: a meter long antenna or a laser [businessinsider.com].
NASA Laser Communications to Provide Orion Faster Connections [nasa.gov]
A laser could enable an orders of magnitude greater data rate over shorter distances, or just enough of a signal to be detectable over light years (even though it will scatter a lot).
Optical SETI [meti.org] (looking for alien lasers) is already a thing [space.com]. An unsuccessful thing, but similar equipment could be used to detect signals from chipcraft. Despite the low power (provided by a 150 mg atomic battery and degraded after 20-30 years), it could be much easier if you have a good idea of where and when the chipcraft will be transmitting.
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(Score: 2) by takyon on Tuesday November 07 2017, @09:22PM
It's nice that we are starting to see a clearer picture of what's around the stars in the Alpha Centauri system. We have already seen protoplanetary disks around a few stars, but those are HOT and YOUNG. In this case we are seeing something with a lot more similarity to our own solar system. And it is the nearest set of stuff that isn't in our solar system. Not just an exoplanet or two, but exoplanets and dust belts. Remember that if you include dwarf planets, our solar system actually has hundreds of "planets" orbiting it, not just 8-9 or the 7 that have been detected around TRAPPIST-1.
Even red dwarf stars have some distant objects orbiting them (>100 AU). Maybe the Sun will even capture a few extreme orbit objects from Proxima/Alpha Centauri in the coming tens of thousands of years. So that is something a little bit interesting during your interstellar drive: rogue rocks that are currently undetectable.
The James Webb Space Telescope could reveal more of what's going on in Alpha Centauri. The LSST [wikipedia.org] will pick up a lot more of our distant Kuiper/Oort objects and maybe Planet Nine.
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