Mystery Solved: How The Orbits Of Extrasolar Planets Became So Eccentric

[Cheetah]

I doubt they would be able to see even Jupiter. The planets we have found so far are huge.

Edit: Are you sure TLC? I thought the smallest planet we had discovered so far was at least 3 times the size of Jupiter?

 

[North King]

Jupiter, possibly Saturn, I believe.

Not Saturn, unless it was right next to the sun and we detected the wobble, IRRC. Saturn has too little mass... Perhaps they might be able to discover it by radiation if it was far enough from the star and the star was bright enough to illuminate it.

 

[The Last Conformist]

I doubt they would be able to see even Jupiter. The planets we have found so far are huge.

Edit: Are you sure TLC? I thought the smallest planet we had discovered so far was at least 3 times the size of Jupiter?

I seem to recall one of 0.5-0.7 Jupiter masses. Saturn is about 0.3.

 

[Renata]

Actually, they've apparently detected one only 1/5 the mass of Pluto.

Clickie.

But that one's orbiting a pulsar; special situation. Will look for more after lunch.

Renata

 

[Masquerouge]

We obviously have a very powerful instinct to see ourselves as unique or somehow special. [...]Ah humanity, gotta love ya, at least youre consistent!:shakehead

I agree with you 100%, dude. It's funny you think so much like me yet puke on the Central Park gates

Or it could be that we detect eccentric orbit planets because they are easier to detect! Seems to me that the doppler shift of star method is specifically easy when the planet has an eccentric orbit.

My astrophysically uneducated mind likes that. Could you explain what's the transit approach is, so I can show off a bit ?

 

[The Last Conformist]

Actually, they've apparently detected one only 1/5 the mass of Pluto.

Clickie.

But that one's orbiting a pulsar; special situation. Will look for more after lunch.

That invites the question if it's a tiny planet or a huge asteroid, I suppose.

 

[Bozo Erectus]

I agree with you 100%, dude. It's funny you think so much like me yet puke on the Central Park gates

Well, at least we'll always have something to argue about To me it looked like a giant, $25 million ad for Tide laundry detergent

 

[Renata]

That invites the question if it's a tiny planet or a huge asteroid, I suppose.

Oh, no, not the "Is Pluto a planet?" debate! *runs screaming*

But anyway, I think the point here was the size of non-luminous object able to be detected, not the classification. Here's one only 14x the size of earth: Mu Arae planet

I'm getting the idea that in order for a planet to be detected, it should be either very close to its star, very very large (or both), or the star it's orbiting should be very dim. Earthlike planets don't fit into any of those categories.

Renata

 

[The Last Conformist]

I'm getting the idea that in order for a planet to be detected, it should be either very close to its star, very very large (or both), or the star it's orbiting should be very dim. Earthlike planets don't fit into any of those categories.

You're getting the right idea, except that a dim primary only helps with visual identification, not doppler.

Edit: As regards Pluto, I'll quote this haiku by Steve Mirsky:

Planet ten, you say?
Boy, do we have news for you;
Pluto got the shove!

 

[Winner]

I think terrestrial planets with stable orbits are rare, but they surely exist. But we've already found planets in habitable zones, mostly jovian size gas giants. These planets often have large number of moons, at least in our Solar system. I think there is a good chance one of them has atmosphere and enough water to form oceans.

 

[Yuri2356]

The fourth planet -- the troublemaker -- was ejected into space.

^I wonder where this guy's going to end up...

 

[betazed]

My astrophysically uneducated mind likes that. Could you explain what's the transit approach is, so I can show off a bit ?

As has been said in this thread already the wobble/doppler shift method depends on the planet being very massive, very close to the star or both. USing such a method it is very difficult to detect an earth like planet.

The transit approach does not use the doppler shift of teh star light but rather detects the tiny drop in the intensity of the light coming from the star as the planet moves in front of it. If you keep looking at the star for a long time you should see the intensity oscillate as the planet orbits around the star. Of couse the planetary orbital plane must be on the same plane as you and the star. The biggest advantage of this approach is that you can apply this method to many stars at once. i.e. you can keep looking at say 10,000 stars at the same time for 1 year.

This is one of the methods that the Terrestrial Planet Finder is going to use when it gets launched (if it gets launched).

 

[The Last Conformist]

^I wonder where this guy's going to end up...

Well, one thing is certain, and that is it's gonna spend alot of time in the middle of nowhere before it gets anywhere.

 

[Masquerouge]

This is one of the methods that the Terrestrial Planet Finder is going to use when it gets launched (if it gets launched).

Thanks for the explanation !