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NASA to Host News Conference on Discovery Beyond Our Solar System

johnfosteruk

By johnfosteruk
in The Astro Lounge

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Davey-T

Davey-T

Posted
Posted
Just now, symesie04 said:

And yet there are many lottery winners.

Used to be 14 million to one chance of winning before they added more balls, guess they thought they had too many winners, probably 50 million to one now.

I don't think that counting on winning the lottery is a sound financial plan for ones old age :grin:

Dave

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Ags

Ags

Posted
Posted

It's a flare stare, so I expect the spikes are flares. Which is not good news for the  planets in the habitable zone - they will be bathed in powerful X-rays during flares.

TRAPPIST-1 can be detected by a small telescopes, but probably not visually! TRAPPIST is the name of 60cm telescope, so the original discovery of 3 planets was made with a relatively modest mirror, but I guess the CCD wasn't exactly cheap!

TRAPPIST_telescope_at_La_Silla_Eso1023e.

To put it differently, TRAPPIST-1 has an apparent magnitude of around 19. My NexStar 4SE can see stuff down to around Mag 11, and every 2.5 increase in aperture adds two visual magnitudes to that. So 10" should let me see 13th mag, 25" would get me to 15th mag, 60" would get me to 17th mag... so no, an amateur scope is not going to make this a visual target. 

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astromackem

astromackem

Posted
Posted
55 minutes ago, Ags said:

It's a flare stare, so I expect the spikes are flares. Which is not good news for the  planets in the habitable zone - they will be bathed in powerful X-rays during flares.

TRAPPIST-1 can be detected by a small telescopes, but probably not visually! TRAPPIST is the name of 60cm telescope, so the original discovery of 3 planets was made with a relatively modest mirror, but I guess the CCD wasn't exactly cheap!

TRAPPIST_telescope_at_La_Silla_Eso1023e.

To put it differently, TRAPPIST-1 has an apparent magnitude of around 19. My NexStar 4SE can see stuff down to around Mag 11, and every 2.5 increase in aperture adds two visual magnitudes to that. So 10" should let me see 13th mag, 25" would get me to 15th mag, 60" would get me to 17th mag... so no, an amateur scope is not going to make this a visual target. 

 

Thanks for that.

Never thought of flares. Wouldnt the flares be a lot weaker coming from a smaller star? Would any atmosphere in the planets deflect the xrays?

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Macavity

Macavity

Posted
Posted
54 minutes ago, Alien 13 said:

Is there a formula available to calculate imaging time vs f ratio/fl/sensor sensitivity etc to capture objects like this?
Thinking of using a 200 mm F4.

http://www.twcac.org/Tutorials/limiting_magnitude_table.htm

I think one could just about get there with a 200mm / F4. But only via
"Electronic Assistance" -- Mag +18+? (See Video Astronomy section!) 
Depending on "sky background", you might then JUST do it? But! :p

Visually? A 20... 30" Reflector? I used to guess "2.5x the aperture"
for a Video Astronomy cam. Not the easiest COLOUR to see tho?!? :o

What was it they claimed of the 200" Hale:
+23 photographically? We can dream... :)

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LukeSkywatcher

LukeSkywatcher

Posted
Posted
On 23/02/2017 at 13:33, Butroz said:

I don't think anyone is claiming that the illustrations are accurate representations - they're just to make the graphic look pretty.

What I believe they are claiming to have a good idea of is the size, mass and orbit of these planets.

I just dont see the need for such illustrations.

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Chris

Chris

Posted
Posted
On 2/22/2017 at 20:31, LukeSkywatcher said:

What still puzzles me about this discovery is:

They claim that all 7 exo planets are "rocky", yet they cant tell what the atmospheres are made up of.

I'm no astro fizzycyst, but i thought it would be easier to discover what a planets atmosphere consists of, rather than what the surface is made up of.

Paul, very luckily the orbits of these planets are edge on to our line of sight, they are transiting exoplanets which pass in front of the parent star from our point of view blocking a little bit of light. This is great because we can produce a light curve of luminosity against time which shows a dip when the planet blocks the parents stars light a little. So immediately from this we can calculate the orbit thus mass, and we can work out the size by how much light is blocked, and if we have the size and mass we can calculate the density! :) 

Also because the planets are transiting, the atmosphere of the planets pass in front of the parent star. Therefore we can look at how the light of the parent star gets absorbed by the planets atmospheres. Looking at absorption lines in spectra can tell us about atmospheric makeup.

I think out the two it's easier to do the math to calculate density, but then again I don't know much about spectroscopy. 

I studied Astro fizzycyst at Uni many Moons ago ;) 

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furrysocks2

furrysocks2

Posted
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24 minutes ago, Chris Lock said:

... we can produce a light curve of luminosity against time which shows a dip when the planet blocks the parents stars light a little. So immediately from this we can calculate the orbit thus mass, and we can work out the size by how much light is blocked, and if we have the size and mass we can calculate the density!

I thought that the periodicity of the dips, ie orbital periods, told you distance from the star, but not mass... is it not the irregularities in the precise timings of the orbits that lets you calculate how the planets interact gravitationally, thus mass?

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Chris

Chris

Posted
Posted
7 minutes ago, furrysocks2 said:

I thought that the periodicity of the dips, ie orbital periods, told you distance from the star, but not mass... is it not the irregularities in the precise timings of the orbits that lets you calculate how the planets interact gravitationally, thus mass?

Yeah sorry, I was just trying skinny things down to get a point across. It's been a long time but think they get the distance from Keplar's third law, and they eihter some how transpose F=Gm1m2/r2 to get m1 or they use combined radial velocity data to help get the mass. 

The point I was trying to make though is that they know what they are doing. Paul bless him seemed to question this.

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Ags

Ags

Posted
Posted

The surface gravity on that star is immense. It's one tenth the sun's mass and one thousandth the volume, so it's a hundred times as dense as the Sun, and I think the surface gravity is ten times higher.

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Chris

Chris

Posted
Posted
6 minutes ago, furrysocks2 said:

You seem to know what you're doing as well. ;)

Is the star small enough and the planets massive and close enough to interact non-trivially?

I think so, they can detect the 'wobble' of a star by a comparatively small oribiting planet now days :) I think all the planets are tidally locked too which shows their interactions are non trivial :) 

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