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(Gizmodo)   We can see two planets orbiting our nearby star. I'm downplaying it, but this is big   (gizmodo.com) divider line
    More: Spiffy, Planet, Star, Extrasolar planet, Solar System, star system, first direct image of multiple exoplanets, Jupiter, host star  
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1942 clicks; posted to Fandom » on 23 Jul 2020 at 7:30 AM (18 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



31 Comments     (+0 »)
 
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2020-07-23 1:55:58 AM  
Depending upon your view of Pluto, there are nine planets orbiting our nearby star.
 
2020-07-23 3:27:14 AM  

Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.


And if you go outside right now, you can probably see three or four of them!
 
2020-07-23 4:24:09 AM  
That's no moon.
 
2020-07-23 6:44:15 AM  
Can we move there?  Like, now?
 
2020-07-23 7:16:37 AM  
Pluto?
 
2020-07-23 8:00:29 AM  

OldRod: Can we move there?  Like, now?


We have the will and the technology, we just haven't found astronauts that can mentally handle 300 million light-years worth of kids asking "Are we there yet?"
 
2020-07-23 8:11:47 AM  
You pesky humans keep in your own star system. Bad enough I have to have you for neighbors watching you bring down the local group property values.
 
2020-07-23 8:27:10 AM  

foo monkey: Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.

And if you go outside right now, you can probably see three or four of them!


Oh, don't take the Beverly Hills tour. It's a rip off.
 
2020-07-23 8:27:41 AM  
Disks. That's the farking amazing thing. Disks.
 
2020-07-23 8:30:59 AM  
I can see Uranus
 
2020-07-23 9:22:17 AM  
I'm not trying to downplay the scientific significance of this achievement, but I have a practical question. How do these two planets show up so brightly when they are backlit by the star (that is behind them)?  Probably there is some significant photo manipulation going on here but if they are gas giants, would they be reflective enough to reflect the light from other nearby stars???
 
2020-07-23 9:29:57 AM  

yakmans_dad: Disks. That's the farking amazing thing. Disks.


Well, not so much.

You shouldn't actually be able to see a full disk like that.  You should only be able to see "half disks" if you were actually resolving the planets, in that you'd see the part that is illuminated by the star they are orbiting, but not the "dark side".

The fact that these are evenly illuminated suggests to me that they cranked the gain up so much that these aren't actually disk images.  What you're seeing is a "false disk".
 
2020-07-23 9:31:01 AM  

dittybopper: The fact that these are evenly illuminated suggests to me that they cranked the gain up so much that these aren't actually disk images


Or, more likely, that it's beyond the resolving capability of the telescope in question.   Or both.
 
2020-07-23 9:41:42 AM  
This *IS* huge, though, despite the fact that we're not actually resolving the disks of the exoplanets in question.

The overwhelming majority of exoplanets detected so far have been through the transit method.  We look at a star and see if it's light dims just a bit when a planet passes in front of us.  It's perhaps the easiest method.

The problem is that we have to be more or less in the orbital plane of those planets to use that method.  Which means that we won't be able to detect roughly 98% of planets if those orbital planes are randomly distributed.

Being able to directly image planets though is a massive improvement.  Orbital plane orientation doesn't matter.

Having said that, there is another caveat:  This method will be harder the smaller the planets are and the closer they are to their own star.  I doubt we could image an Earth-sized planet at 1 AU distance at 300 light years distance, though we probably could detect one through the transit method.
 
2020-07-23 9:46:07 AM  

foo monkey: Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.

And if you go outside right now, you can probably see three or four of them!


At least one of them.

dittybopper: dittybopper: The fact that these are evenly illuminated suggests to me that they cranked the gain up so much that these aren't actually disk images

Or, more likely, that it's beyond the resolving capability of the telescope in question.   Or both.



They're resolving in the deep infrared, which is going to include a lot more radiated light as well as reflected. The disk only matters for the reflected light, whereas depending on how the planets are spinning, there is more likely to be thermally equalized IR radiation.

I suspect that if they're tidally locked, then you would have IR hot spots on the sun-facing side, but as they're gas giants they can convect the heat around the planet more.

On Earth, we radiate away ~20 IR photons for every one visible photon we absorb.

We also don't know exactly how the ecliptic of the other system is tilted with respect to us. It could be that we're seeing the planets at an angle that exposes more of the illuminated face to us.
 
2020-07-23 9:51:47 AM  

OldRod: Can we move there?  Like, now?


Given the age of the system I'm guessing you wouldn't want to set foot on amy rocky planets yet.

But, by the time we have the technology to traverse 300 million lightyears reasonably you should be fine.
 
2020-07-23 9:55:13 AM  

BlazeTrailer: OldRod: Can we move there?  Like, now?

Given the age of the system I'm guessing you wouldn't want to set foot on amy rocky planets yet.

But, by the time we have the technology to traverse 300 million lightyears reasonably you should be fine.


300 light years. Not 300 million.
 
2020-07-23 10:31:54 AM  

Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.


If you count Pluto you'd have to include the other 2,000+  trans-Neptunian objects in the Solar System.

https://en.wikipedia.org/wiki/Trans-N​e​ptunian_object
 
2020-07-23 10:43:42 AM  

BeotchPudding: Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.

If you count Pluto you'd have to include the other 2,000+  trans-Neptunian objects in the Solar System.

https://en.wikipedia.org/wiki/Trans-Ne​ptunian_object


Then we can have 2,000+ planets for a while. If we can't consistently count how many moons the Earth has then I see no reason to stick with only one figure for the number of planets around the Sun.

QI Compilation | Alan VS The Moon(s)
Youtube CIqOsM6_3Dw
 
2020-07-23 11:14:20 AM  

PirateKing: They're resolving in the deep infrared, which is going to include a lot more radiated light as well as reflected. The disk only matters for the reflected light, whereas depending on how the planets are spinning, there is more likely to be thermally equalized IR radiation.


First of all, it's not deep infrared, as the telescope is only capable of observing mid-IR, near-IR, and visible light.

But soft, let's do the math and see if the VLT has enough resolution to resolve planetary disks at 300 light years, even at visible light which, being the shortest wavelength, provides the highest resultion.

SPHERE, the instrument used for this, has a resolution of 0.02 arcseconds.
https://en.wikipedia.org/wiki/Very_La​r​ge_Telescope#Telescopes

https://astronomy.stackexchange.com/q​u​estions/20695/how-big-is-one-arcsecond​-at-various-distances
One arcsecond at distance of one parsec is one astronomical unit (AU), by definition

A parsec is 3.3 light years, and 1 AU is 93 million miles.

So at one parsec, SPHERE could resolve something (93,000,000 * 0.02) = 1,860,000 miles in diameter.  For comparison, the Sun has an equatorial diameter of about 860,000 miles.   So SPHERE couldn't even resolve the Sun as a disk at 75% of the distance to Alpha Centauri, and the sun is much larger than those planets.

At 300 light years, or 90.9 parsecs, the smallest resolution SPHERE could achieve is 1,860,000 miles * 90.9 = 169.1 million miles.

That means that the minimum sized object that SPHERE could resolve is about 1.82 AU in size, or nearly the diameter of Earth's orbit.

Those aren't disks.  What you're seeing is an artifact of how the images were made.
 
2020-07-23 11:16:59 AM  

PirateKing: I suspect that if they're tidally locked, then you would have IR hot spots on the sun-facing side, but as they're gas giants they can convect the heat around the planet more.


Tidally locked at distances of 160 AU and 320 AU?

That's heavy, Doc.
 
2020-07-23 11:25:38 AM  

dittybopper: But soft, let's do the math and see if the VLT has enough resolution to resolve planetary disks at 300 light years, even at visible light which, being the shortest wavelength, provides the highest resultion.


I actually cheated and just used the published resolution of SPHERE, so you can ignore the part about using visible light.  I was going to do the calculations the hard way, but for brevity just used the published resolution.

Interestingly, even using the highest resolution instrument, the PIONIER interferometer with a resolution of 0.0025 arcseconds, at 300 light years would be be able to image something 21.1 million miles in diameter.
 
2020-07-23 11:50:03 AM  
Just for fun, I wonder what kind of resolution would be needed to actually image these planets.  We'll take Jupiter as our single "pixel" size, so images of these "super-Jupiters" would be more than a single pixel.

Jupiter has a mean diameter of roughly 87,000 miles.

That's about 87,000 / 93,000,000 = 0.00094 AU

So to resolve Jupiter as a single pixel at 1/12 of a Kessel Run, you need a resolution of 0.00094 arcseconds.

At 90.9 parsecs, it's 0.00094 / 90.9 = 0.0000103 arcseconds.

That's 2 whole orders of magnitude higher than VLT can achieve.
 
2020-07-23 11:58:30 AM  

OldRod: Can we move there?  Like, now?



At 14 times the size of Jupiter, I will pass on that suggestion.
 
2020-07-23 12:07:34 PM  

Diagonal: OldRod: Can we move there?  Like, now?


At 14 times the size of Jupiter, I will pass on that suggestion.


Might have moons. If so at least some of them would be kept warm by tidal friction. You'd have to bring your own flashlight though, the star would be a pinpoint at that distance. Not sure about how well the planet itself would show up in the sky from a moon. That is incredibly distant.
 
2020-07-23 12:30:24 PM  

dittybopper: dittybopper: But soft, let's do the math and see if the VLT has enough resolution to resolve planetary disks at 300 light years, even at visible light which, being the shortest wavelength, provides the highest resultion.

I actually cheated and just used the published resolution of SPHERE, so you can ignore the part about using visible light.  I was going to do the calculations the hard way, but for brevity just used the published resolution.

Interestingly, even using the highest resolution instrument, the PIONIER interferometer with a resolution of 0.0025 arcseconds, at 300 light years would be be able to image resolve something 21.1 million miles in diameter.


FTFM.
 
2020-07-23 12:46:16 PM  

yakmans_dad: Disks. That's the farking amazing thing. Disks.


Sorry to have brought the subject up. Thanks for the informative corrections, though.

/Smart boy wanted.
 
2020-07-23 1:23:03 PM  
Not "our nearby star" subby.
 
2020-07-23 1:53:10 PM  

Dr.Fey: Depending upon your view of Pluto, there are nine planets orbiting our nearby star.


Depending on your view of Pluto, there are either eight or 135 confirmed and 550 pending planets in the solar system (with 30-50 being discovered per year). When it was discovered, it was the 10th planet.

Further, had Lowell actually noticed it on plates he took years before it was officially found (he calculated its mass to be at least 7-10 earths so he wasn't interested in some miniscule smudge of cosmic nothing) it would have been the 12th (the former 5th and 6th don't get any status back with Pluto recognition).

Extra further, if we go by the definition of planet used at the time, it failed on more points than it does the new one. It was initially given an exception because of a rule against creating a "class of one," that left mis-classified objects (like the former 5th through 6th planets) where they were until a new class can absorb them. Then, the same year a new classification that it actually fit was created, we discovered Ceres and the exception was continued because we didn't know of non-planet objects that had moons, except we knew thousands before Pluto's eventual demotion, including many within the classification created to absorb it (and a second one that it fit into even better that predated its demotion by over a decade).
 
2020-07-23 2:41:04 PM  

yakmans_dad: BlazeTrailer: OldRod: Can we move there?  Like, now?

Given the age of the system I'm guessing you wouldn't want to set foot on amy rocky planets yet.

But, by the time we have the technology to traverse 300 million lightyears reasonably you should be fine.

300 light years. Not 300 million.


Oops, thanks for the correction.

However, I stand by my point.
 
2020-07-23 2:59:39 PM  

yakmans_dad: yakmans_dad: Disks. That's the farking amazing thing. Disks.

Sorry to have brought the subject up. Thanks for the informative corrections, though.

/Smart boy wanted.


No, don't be sorry.

First of all, I got to do math, so that's fun.  It's especially fun for this kind of stuff.  I haven't had so much fun since I proved that Predators are legally blind:  https://www.fark.com/comments​/9876503/​113199800#c113199800

Second, it's a vivid illustration of just how vast space really is.  Even with the best telescopes available we can't resolve planets at a distance.   Remember, just six years ago, this were the best images we had of Pluto:

cdn.britannica.comView Full Size
 
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