A Trio of Super-Earths

[blobrana]

A harvest of low-mass exoplanets discovered with HARPS
"Today, at an international conference, a team of European astronomers announced a remarkable breakthrough in the field of extra-solar planets. Using the HARPS instrument at the ESO La Silla Observatory, they have found a triple system of super-Earths around the star HD 40307. "

Read more (http://www.eso.org/public/outreach/press-rel/pr-2008/pr-19-08.html)

[draqon]

super-Earth, heh...you mean like Jupiter gravity like?

[Enmos]

super-Earth, heh...you mean like Jupiter gravity like?

It is in the article :bugeye:

The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively.

[draqon]

It is in the article :bugeye:

The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively.

yeah well the gravity depends on their density...you know...

[Enmos]

yeah well the gravity depends on their density...you know...

No, mass depends on density.

[draqon]

No, mass depends on density.

you are right, my bad.

[draqon]

g=GM/(r^2)

[kaneda]

The trio are close in on their star. As the article says, planets further away are harder to find.

The smaller planet masses just under half Uranus (which has a diameter of 16,000 miles) so maybe a diameter of 12-13,000 miles? (depending on density).

"This implies that one solar-like star out of three harbours such planets."

Certainly good news.

[Letticia]

Gravity depends on mass and radius.

Density also depends on mass and radius.

But dependencies are very different, and there is no direct relationship between density and gravity. A small dense object may have less gravity than a large low-density one.

[Enmos]

Gravity depends on mass and radius.

Density also depends on mass and radius.

But dependencies are very different, and there is no direct relationship between density and gravity. A small dense object may have less gravity than a large low-density one.

Well, I assumed that was too obvious to mention. But if you want to go there, gravity depends on mass and volume.

[kmguru]

Since we humans can handle 2g to 4g fairly easily, I assume, there could be life on planets where the gravity is 2 to 4g of Earth....short stocky fellas like the Gurkhas....

[orcot]

Since we humans can handle 2g to 4g fairly easily, I assume, there could be life on planets where the gravity is 2 to 4g of Earth....short stocky fellas like the Gurkhas....
Humans can survive that? No offence I believe they can easly survive high speed manauvres produces multiple G's but how abouth for weeks or months?

Sure there could be life and some plants and animal life but gravity wouldn't be friendly

[Enmos]

Bacteria can, no doubt..
So life may evolve into more intelligent lifeforms on high gravity planets as well..

[Cazzo]

It is in the article :bugeye:

The planets, having 4.2, 6.7, and 9.4 times the mass of the Earth, orbit the star with periods of 4.3, 9.6, and 20.4 days, respectively.

With short orbits like that, they're very close to their sun, so they're probably VERY hot planets.

[orcot]

It's K star (colder then our sun but still pretty hot) So yeah it will be hot.

[eburacum45]

They'll be heated by tidal heating too, so the crust will probably be molten; but exactly how much of each planet consists of core, how much consists of mantle, and how much consists of gaseous atmosphere is entirely a matter of conjecture (unless they get a transit or three).

One sentence caught my eye
"Clearly these planets are only the tip of the iceberg," says Mayor. "The analysis of all the stars studied with HARPS shows that about one third of all solar-like stars have either super-Earth or Neptune-like planets with orbital periods shorter than 50 days."

I have invented numerous imaginary planetary systems for worldbuilding purposes, (example here (http://www.orionsarm.com/worlds/Pen-y-ghent.html)) but I must admit that only a few of my imaginary systems have super-Earths or hot Neptunes in the innermost orbits. Like many worldbuilders, I have always assumed that many or most star systems would resemble ours, with smaller terrestrials like Mercury occupying the innermost orbits. This turns out to be unlikely.

[blobrana]

I have always assumed that many or most star systems would resemble ours, with smaller terrestrials like Mercury occupying the innermost orbits. This turns out to be unlikely.

Hum,
that could be a artefact of the current measuring techniques.
ie we don't see any exoplanet moons - but we cant presume there aren't any.

[eburacum45]

I certainly wouldn't have guessed that as many as one-third of all systems would have a hot superterrestrial, though.

[Walter L. Wagner]

There will be a huge mix of systems, including a high percentage with double stars in orbit about each other, and with planets in orbit about each star; and some with triple stars.

Under some theories, almost all planets form initially as gas-ball giants [failed stars], but are later stripped of their lightest gases [H & He], leaving behind the less-abundant heavier gases [H2O, CO2, NH3, etc.] and the molten metal/rock inner-core. The evaporation of the lightest gases is driven primarily by nearby OB stars in the stellar nurseries that generate multiple star-systems, which eventually then drift apart.

Consequently, we can expect to see a huge variety of planetary systems. Let's get some good optics out there in space, so we don't just have to infer the mass of the planet by the star's wobble!

[Reiku]

I agree.

[kmguru]

Are not we building the next generation telescopes? Could it be possible to have say an optical digital telescope array to increase light gathering capabilities and combine the images?

[weed_eater_guy]

I think they already do this...

http://en.wikipedia.org/wiki/Aperture_synthesis

So far though, I'm not entirely sure if this is done for the purpose of increasing the accuracy of measurements or for developing sharper and sharper images.

Who knows, maybe throwing a few smaller optical scopes into high orbit would be cheaper and better than a single large scope, but I really don't know enough to say.

[kmguru]

Perhaps send 10,000 canon cameras up there that can be synchronized to the same location. imagine each with 10 megapixels...

[MR. Champagne]

could we even observe an earthsized planet with our current techniques?

[Enmos]

could we even observe an earthsized planet with our current techniques?

No but they are getting closer.

If they really do find uninhabited habitable earth sized planets, which is almost unimaginable, 90% of humanity should relocate there.

[kmguru]

Visual will be difficult due to their Sun. But we should be able to pick up the radio signals if there is advanced life there. But one needs a huge antenna in space.

[orcot]

yeah you would only be able to see the planets phases, even less if the planet is under a different angle then our planet (witch it most probably will be), So if we would be able to look at a planet then we might in a extreme example only see it's northern pole during spring and autum.

Still as long as we're able to determin it's atmospheric composition and perhaps pressure. We might learn more then any picture might teach us. Unless offcourse if the darkside of the exo planet is lit by the lights of alien cities

[blobrana]

“Massive, rocky worlds called 'super-Earths' – even those orbiting searingly close to their stars – may provide the right conditions for life, new research suggests.”

Read more (http://space.newscientist.com/channel/astronomy/dn14305-hot-superearths-could-host-life-after-all.html)