Three new planets discovered

[tkdguy]

Link

 

Also check the NGD. I posted a link to the San Francisco Chronicle's latest science articles.

[Cancer]

Re: Three new planets discovered

 

I haven't found a technical preprint of this announcement yet, but I've only been looking for three minutes.

 

An interesting item is that this system was reported last year to have an infrared excess indicating relatively warm dust in the system. The "relatively warm" suggests a location close in to the star, like 1 AU or so ... that's howling distance of what our Asteroid Belt is. There was no sign of cold dust (stuff that would Kuiper Belt distance).

 

EDIT: Found it. the 18 May issue of Nature. Also an ESO press release.

Masses are 10.2, 11.8, and 18.1 earth masses each. Distances are 0.08, 0.19, 0.63 AUs from the central star. Haven't found the full number set yet; I'd like to see the orbital eccentricities.

[austenandrews]

Re: Three new planets discovered

 

My first thought is, man, those are some huge chunks of rock.

[Cancer]

Re: Three new planets discovered

 

I doubt the planets are rocky ... that's Neptune-class size ... but there's no real way to know at this point.

[austenandrews]

Re: Three new planets discovered

 

Dunno, just going off what the article said.

[BobGreenwade]

Re: Three new planets discovered

 

It looks like the third planet, though appropriate temperature-wise, is too big for even a colony of Heavies. Maybe it has a moon or something....

 

And it increasingly seems like only a matter of time before one colonizable by Humans is discovered -- probably, I'd guess, within our lifetimes (if not within this decade).

[Nyrath]

Re: Three new planets discovered

 

Well, it is my understanding that current astronomical techniques cannot detect an extrasolar planet small enough to be Earth-sized. So all the solar systems we currently know to have super-Jupiters could also have earthlike planets, for all we know.

 

http://oklo.org/?p=89

http://www.centauri-dreams.org/?p=669

[Cancer]

Re: Three new planets discovered

 

Strictly speaking there could be Earthlike planets in there, but for any system where you have one of those Jovian guys closer to the star than about 2.5 AU, it's unlikely.

 

The working hypothesis for getting giant planets close to their star involves a "migration" through the disk at early times, where gas-drag on a forming Jovian planet causes its orbit to decay from where the planet formed (which has to be outside the "frost line" where ices can condense, about 5 AU) to where the planet is now found. Whether or not the same gas-drag decay causes planets that started with smaller orbits to decay into the star or not (one can make arguments back and forth about whether terrestrial planets would be "fluffy" enough to have appreciable gas drag), CERTAINLY having a jovian planet pass through the zone where the terrestrial planets were could be sufficient to accrete those little rocky planets onto the big jovian guy, or eject the little planets from the system. In either case, it is expected that there to are no terrestrial planets in a system with large planets close to the star.

 

EDIT: Managed to find the paper. The orbital eccentricities are smallish (0.10 +/- 0.04, 0.13 +/- 0.06, 0.07 +/- 0.07). Also their observations rule out any saturn-mass planet or larger any closer in than 4 AU.

[SirViss]

Re: Three new planets discovered

 

There is something in the works to detect Earth-size planets:

 

Kepler Mission

 

[Edit: I should spell Kepler properly.]

[Cancer]

Re: Three new planets discovered

 

There is something in the works to detect Earth-size planets:

 

Keppler Mission

I'll have to check on this. An allied mission, TPF (which is linked from the Kepler page you have linked there), had its budget zeroed out back in Feb/March in the latest version of the President's budget. I don't recall a specific mention of Kepler at the time. The TPF site doesn't mention the budget axe, so even if the same happened to Kepler it might not say so on its site.

[Cancer]

Re: Three new planets discovered

 

Found a neat figure (unfortunately buried behind a subscription-only wall) about detectability of planets. This was by the OGLE group, who are one of the microlensing teams.

 

Microlensing has a peculiar set of dependences, but it looks like current groundbased microlensing programs could detect an Earth-mass planet if things were set up exactly right. That's a low-odds set of circumstances; Earth itself can't fulfil that (1 Earth-mass planets need to be at 2-3 AU for the existing microlensing programs to be able to pick them out).

 

Right now, using existing technology, the only Solar System planet we could detect is Jupiter. (We have to wait another decade to detect Saturn; you have to observe a system through at least a full orbit to be sure of a planet, and the tech hasn't existed as long as Saturn's orbital period.)

 

The very rudimentary statistics suggests that Neptune-class planets with orbits that are in the couple-of-AU size range are reasonably common.

[Nyrath]

Re: Three new planets discovered

 

Found a neat figure (unfortunately buried behind a subscription-only wall) about detectability of planets. This was by the OGLE group' date=' who are one of the microlensing teams.[/quote']

There is a problem from a game standpoint. While conventional planet detection techniques are wonderful for detecting planets that are close to Earth (i.e., within a few hundred light years), microlensing by its very nature tends to only detect planets that are tens of thousand light years away.

 

The rationale for this is available upon request, but I didn't want to bore anybody with the tedious details.