APOD: Proxima Centauri: The Closest Star (2016 Jan 18)

[APOD Robot]

Proxima Centauri: The Closest Star

Explanation: Does the closest star to our Sun have planets? No one is sure -- but you can now follow frequent updates of a new search that is taking place during the first few months of this year. The closest star, Proxima Centauri, is the nearest member of the Alpha Centauri star system. Light takes only 4.24 years to reach us from Proxima Centauri. This small red star, captured in the center of the featured image by the Hubble Space Telescope, is so faint that it was only discovered in 1915 and is only visible through a telescope. Telescope-created X-shaped diffraction spikes surround Proxima Centauri, while several stars further out in our Milky Way Galaxy are visible in the background. The brightest star in the Alpha Centauri system is quite similar to our Sun, has been known as long as recorded history, and is the third brightest star in the night sky. The Alpha Centauri system is primarily visible from Earth's Southern Hemisphere. Starting last week, the European Southern Observatory's Pale Red Dot project began investigating slight changes in Proxima Centauri to see if they result from a planet -- possibly an Earth-sized planet. Although unlikely, were a modern civilization found living on a planet orbiting Proxima Centauri, its proximity makes it a reasonable possibility that humanity could communicate with them.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Ann]

Proxima Centauri is a special star is a special star for us Earthlings, there is no doubt about that. And a special star needs a portrait. Today's APOD is the perfect poster for the Pale Red Dot project. Surely it would be fantastic if an Earth-sized planet was found in orbit around Proxima. I think that if that was the case, NASA would be under huge pressure to send a probe to Proxima.

Click to view full size image

Alpha and Proxima Centauri.
Photo: ESO.

But while today's APOD is a great poster for the Pale Red Dot project, there are other images that I myself prefer when it comes to portraying Proxima. One of the two images that are my favorites is at left. What I love about it is that it really shows us how bright Alpha Centauri Aa and Ab are, how close together they are, and how distant faint little Proxima is from the bright pair.

Click to view full size image

Proxima Centauri.
Photo: David Malin.

My other favorite portrait of Proxima Centauri is this one. I love seeing it in a crowded field of stars and think that it is different from all the other similar-looking stars seemingly surrounding it in that it is so (comparatively) extremely close to us.

But good luck with the Pale Red Dot project! It would be fantastic if it was successful.

Ann

[Ann]

So what do you think, those of you who are knowledgeable about spaceflight? Suppose the search for an Earth-sized planet in orbit around Proxima Centauri is successful. Suppose NASA decides to send a probe there to investigate. How fast could that probe possibly arrive, under the very best of circumstances?

Suppose there is a ten-year-old kid (born in 2005 or 2006) who regularly, if anonymously, visits Starship Asterisk*. Suppose this kid has good genes and is going to live well into his or her nineties.

Could this kid possibly be alive when the first probe from Planet Earth reaches the Proxima Centauri system?

Ann

[LMMT]

Pandora.

[JMac]

@Ann:
Quick scratchup:
Using miles & 'per hour' &c as those are more familiar concepts:
Voyager 1 now approaching 38.5 years in operation. Its transmissions take 16.33 hours to reach us; much shorter than 1 year, in fact only 0.001864155 of a year. It's ~110AUs from Earth; 1 AU = ~93 million miles, ergo Voyager 1 is ~10,230,000,000 (10 billion, 230 million) miles away.

Year = 8630 hours; V'ger1 has been traveling 332,255 hours, translates to 10,230,000,000 ÷ 332255 = 30,790 miles/hour.
Proxima Cent = ~4.2 light years, or ~24.7 trillion* miles.
*2.46897e+013 or 24,689,700,000,000 miles, divided by V'ger1's 30,790 miles/hour = 801,873,985.06 hours = 91,538.13 years.

Now pause for a moment & consider the trillions of dollars of debt we're in.

Someone check my math, but if you started with a child only 1 year old vice 10, it wouldn't really help much.

Very few people can actually grasp the true vastness of space.
Very few people can actually grasp the true concept of what a trillion is.

[Ann]

@Ann:
Quick scratchup:
Using miles & 'per hour' &c as those are more familiar concepts:
Voyager 1 now approaching 38.5 years in operation. Its transmissions take 16.33 hours to reach us; much shorter than 1 year, in fact only 0.001864155 of a year. It's ~110AUs from Earth; 1 AU = ~93 million miles, ergo Voyager 1 is ~10,230,000,000 (10 billion, 230 million) miles away.

Year = 8630 hours; V'ger1 has been traveling 332,255 hours, translates to 10,230,000,000 ÷ 332255 = 30,790 miles/hour.
Proxima Cent = ~4.2 light years, or ~24.7 trillion* miles.
*2.46897e+013 or 24,689,700,000,000 miles, divided by V'ger1's 30,790 miles/hour = 801,873,985.06 hours = 91,538.13 years.

Now pause for a moment & consider the trillions of dollars of debt we're in.

Someone check my math, but if you started with a child only 1 year old vice 10, it wouldn't really help much.

Very few people can actually grasp the true vastness of space.
Very few people can actually grasp the true concept of what a trillion is.

Thanks!

Uh, can anyone convert those miles into kilometers?

Anyway, if I got you correctly, a trip to Proxima Centauri, using current technology, would take more than 91,000 years.

Click to view full size image

Boy with bionic arm.
Source: http://news.bbc.co.uk/cbbcnews/hi/newsi ... 048484.stm

Sorry, 10-year-old kid. No closeups of any Proxima planet for you.

Unless we really figure out how to replace our worn-out body parts so that we can extend our life spans into thousands of years.

Ann

[jisles]

Pace today's APOD, Proxima Centauri is not unusually faint. Its apparent magnitude is 11 and it can be seen in a small telescope. What was discovered in 1915 was its closeness to us rather than its existence.

John

[rstevenson]

So what do you think, those of you who are knowledgeable about spaceflight? Suppose the search for an Earth-sized planet in orbit around Proxima Centauri is successful. Suppose NASA decides to send a probe there to investigate. How fast could that probe possibly arrive, under the very best of circumstances?

With our current knowledge we just might be able to make a small vehicle that could reach something like 10% of the speed of light over that sort of distance, and assuming constant acceleration and no braking at the other end (kind of like the recent Pluto mission), that makes for an average speed of 5%, or 1/20th of light speed. So for such a vehicle to reach Proxima Centauri, at 4.24 ly distance, it would take about 20 x 4.24 = 84.8 years. It would then take a further 4.24 years for the pictures to get back here, for a total of about 89 years from launch. Note that the above is wildly optimistic. Although the theory of how such a ship would operate is understood, no one has ever tried to build one.

I.e., see Interstellar travel

There is one small problem (only one?!) To send back pictures in a reasonably coherent beam, such that we could have some likelihood of receiving them, would require a large powerful transmitter. And as soon as you start saying "large, powerful" you go beyond the ability of our current technology to accelerate the ship to that sort of speed. So I'm not sure any such venture would be useful.

Rob

[neufer]

So what do you think, those of you who are knowledgeable about spaceflight? Suppose the search for an Earth-sized planet in orbit around Proxima Centauri is successful. Suppose NASA decides to send a probe there to investigate. How fast could that probe possibly arrive, under the very best of circumstances?

• Using current technology (with interstellar speeds of ~ 0.0001 c ~ twice Voyager speed)
  it would take ~ 30,000 years to effect a ~ 3 ly Proxima Centauri flyby.

<<Among the known stars, Proxima Centauri has been the closest star to the Sun for about 32,000 years and will be so for about another 33,000 years, after which the closest star to the Sun will be Ross 248. In 2001, J. García-Sánchez et al. predicted that Proxima will make its closest approach to the Sun, coming within 3.11 ly of the latter, in approximately 26,700 years. A 2010 study by V. V. Bobylev predicted a closest approach distance of 2.90 ly in about 27,400 years.>>

• A much quicker trip to orbit Alpha Centauri might take just ~ 8,000 years using a large solar sail:

<<A ... physically realistic [interstellar] flight approach would be to use the light from the Sun to accelerate [a solar sail]. The ship would first drop into an orbit making a close pass to the Sun, to maximize the solar energy input on the sail, then the ship would begin to accelerate away from the system using the light from the Sun to keep accelerating. Acceleration will drop approximately as the inverse square of the distance from the Sun, and beyond some distance, the ship would no longer receive enough light to accelerate it significantly, but would maintain its course due to inertia. When nearing the target star, the ship could turn its sails toward it and begin to use the outward acceleration to decelerate. Additional forward and reverse thrust could be achieved with more conventional means of propulsion such as rockets. Similar solar sailing launch and capture were suggested for directed panspermia to expand life in other solar system. Velocities of 0.0005 c could be obtained by solar sails carrying 10 kg payloads, using thin solar sail vehicles with effective areal densities of 0.1 g/m2 with thin sails of 0.1 µm thickness and sizes on the order of one square kilometer.>>

[Ann]

Art, your latest post was your post number 12345, 1,2,3,4,5.

I like it!

Ann

[Chris Peterson]

With our current knowledge we just might be able to make a small vehicle that could reach something like 10% of the speed of light over that sort of distance, and assuming constant acceleration and no braking at the other end (kind of like the recent Pluto mission), that makes for an average speed of 5%, or 1/20th of light speed. So for such a vehicle to reach Proxima Centauri, at 4.24 ly distance, it would take about 20 x 4.24 = 84.8 years. It would then take a further 4.24 years for the pictures to get back here, for a total of about 89 years from launch. Note that the above is wildly optimistic. Although the theory of how such a ship would operate is understood, no one has ever tried to build one.

It would probably be beyond our current capability. It would not be small, and it would cost more than any other public project ever funded. We don't know how to shield a craft at 0.1c from the kinetic impact of space dust. We don't even know how to make electronics that can reliably survive for 100 years (solid state chips grow internal shorts and fail in decades).

Realistically, this is beyond our means.

[bystander]

Does the closest star to our Sun have planets? No one is sure -- but you can now follow frequent updates of a new search that is taking place during the first few months of this year. ...

http://asterisk.apod.com/viewtopic.php?t=35562

[NGC3314]

Pace today's APOD, Proxima Centauri is not unusually faint. Its apparent magnitude is 11 and it can be seen in a small telescope. What was discovered in 1915 was its closeness to us rather than its existence.

To point that up - these images were done during class projects using a remotely operated telescope in Chile, comparing Proxima Centauri's apparent positions in 2010 and 2014. Even if it weren't the brightest star in this cutout, that's a big jump over 4 years.

[tetrodehead]

Split NGC3314's image so that the two are side by side, cross your eyes and Bobs your auntie. Stereo pair with Prox jumping out at you.
Nice eye candy.

[heehaw]

The big response on this is wonderful, and tells us how much we care about getting out into the Universe!
Now let's be practical. We fund our best shot, and we send it off to Proxima etc. A hundred years later, our technology is vastly better, so we send off a vastly better, one vastly faster. A hundred years after that, we send a REALLY vastly better one off, REALLY vastly faster. A hundred years after that... Gee, a cosmic parade of clown cars! Moral: Forget sending anything to Alpha Centauri and friends for now, please?

[Ron-Astro Pharmacist]

If a star gives good evidence for close-up investigation, journeying there will need to be planned exquisitely with respect to where it will be. (As Art pointed out) Though others in the area are fun to watch too.

[neufer]

Click to play embedded YouTube video.

Art, your latest post was your post number 12345

1,2,3,4,5.

I like it!

Ann

[Boomer12k]

Wow....great image...great idea...maybe SETI should send a tight beam signal there...see if anything returns. That at least is doable, I would think.

Maybe we revive Wernher von Braun's Cesium Ship.....though small and unmanned...

:---[===] *

[Ann]

Click to play embedded YouTube video.

Art, your latest post was your post number 12345

1,2,3,4,5.

I like it!

Ann

I find that video extraordinarily strange.

I guess a calculation as weird as that one is only used in string theory and the like. Or do you know of an instance when it is used in "real life", like for example calculating the strength of a bridge?

Ann

[neufer]

...maybe SETI should send a tight beam signal there...see if anything returns. That at least is doable, I would think.

Active SETI generally involves:

• 1) Northern Hemisphere radio telescopes
  2) Known extraterrestrial planetary systems

Neither applies with Proxima Centauri.

[MarkBour]

Ann, thanks for the additional images and the intriguing question. This will be a great telescopic investigation. Goldilocks around Proxima Centauri is going to be different than around Sol, of course.

[rstevenson]

With our current knowledge we just might be able to make a small vehicle that could reach something like 10% of the speed of light over that sort of distance, and assuming constant acceleration and no braking at the other end (kind of like the recent Pluto mission), that makes for an average speed of 5%, or 1/20th of light speed. So for such a vehicle to reach Proxima Centauri, at 4.24 ly distance, it would take about 20 x 4.24 = 84.8 years. It would then take a further 4.24 years for the pictures to get back here, for a total of about 89 years from launch. Note that the above is wildly optimistic. Although the theory of how such a ship would operate is understood, no one has ever tried to build one.

It would probably be beyond our current capability. It would not be small, and it would cost more than any other public project ever funded. We don't know how to shield a craft at 0.1c from the kinetic impact of space dust. We don't even know how to make electronics that can reliably survive for 100 years (solid state chips grow internal shorts and fail in decades).

Small is relative. It would require a truly excellent version of the kind of nuclear engines used for the last half century in nuclear subs, so that much is not an unknown technology, nor is it prohibitively expensive. That engine would be the source of the electricity used to power the ion (likely) drive. That kind of drive is something we've done a few times, but not at the scale this venture would require, so it's definitely pushing the envelope. As for cost, we routinely put up 1/2 billion dollar satellites now, and have spent multiple billions on the ISS. I don't see this probe being more expensive than that (unless NASA was doing it.) The electronics are a problem, true, but I can at least imagine ways to improve aspects of that which aren't routinely used in consumer products. Again, our existing satellite and rover technology would suggest the way forward. Finally, there are credible suggestions for using a magnetic field to push fine dust and molecules out of the way at such speeds, though there's been no proof of concept attempted yet.

It is well beyond our current practice, true, but not beyond making a reasonable attempt at planning such a trip if it was deemed useful. And any proof that there was a living world at Proxima Centauri would likely trigger just such a planning exercise. And planning exercises rarely succeed if they start with "It can't be done." Better to start with "Let's see what's possible."

Rob

[neufer]

I guess a calculation as weird as that one is only used in string theory and the like. Or do you know of an instance when it is used in "real life", like for example calculating the strength of a bridge?

• How about calculating the strength of a traversable wormhole

<<The regularization of 1 + 2 + 3 + 4 + ⋯ is involved in computing the Casimir force for a scalar field in one dimension. An exponential cutoff function suffices to smooth the series, representing the fact that arbitrarily high-energy modes are not blocked by the conducting plates. The spatial symmetry of the problem is responsible for canceling the quadratic term of the expansion. All that is left is the constant term −1/12, and the negative sign of this result reflects the fact that the Casimir force is attractive.

It has been suggested that the Casimir forces have application in nanotechnology, in particular silicon integrated circuit technology based micro- and nanoelectromechanical systems, silicon array propulsion for space drives, and so-called Casimir oscillators.

The Casimir effect shows that quantum field theory allows the energy density in certain regions of space to be negative relative to the ordinary vacuum energy, and it has been shown theoretically that quantum field theory allows states where the energy can be arbitrarily negative at a given point, Many physicists such as Stephen Hawking, Kip Thorne, and others therefore argue that such effects might make it possible to stabilize a traversable wormhole.>>

[Ann]

I guess a calculation as weird as that one is only used in string theory and the like. Or do you know of an instance when it is used in "real life", like for example calculating the strength of a bridge?

How about calculating the strength of a traversable wormhole

Right! So all we have to do is to travel to the nearest(?) black hole, V4641 Sgr, 1600 light years away, hope there is a wormhole in the vicinity of it, and dive into the wormhole while stabilizing it with the 1 + 2 + 3 + 4 + ⋯ = −1/12 equation! Who knows, with the help of that wormhole we might even end up in the Proxima Centauri system and see for ourselves whether it has planets or not!

Ann

[Cousin Ricky]

The brightest star in the Alpha Centauri system is quite similar to our Sun, has been known as long as recorded history, and is the third brightest star in the night sky.

According to my sources, Alpha Centauri is 3rd brightest only when considered as a pair. When they are considered separately, Arcturus (-0.04) barely edges out Alpha Cen A (-0.01, class G2V) for 3rd place. According to my rusty math, the combined light of A and B comes in at -0.29, which handily beats out Arcturus.