Munich, April 24: An international team of astronomers from Switzerland, France and Portugal have discovered the most Earth-like planet outside our Solar System to date. Posted on 04/24/2007 1:41:01 PM PDT by Sopater
Munich, April 24: An international team of astronomers from Switzerland, France and Portugal have discovered the most Earth-like planet outside our Solar System to date.
The planet has a radius only 50 percent larger than Earth and is very likely to contain liquid water on its surface.
The research team used the European Southern Observatory’s (ESO’s) 3.6-m telescope to discover the super-Earth, which has a mass about five times that of the Earth and orbits a red dwarf already known to harbour a Neptune-mass planet.
Astronomers believe there is a strong possibility in the presence of a third planet with a mass about eight times that of the Earth in the system.
However, unlike our Earth, this planet takes only 13 days to complete one orbit round its star. It is also 14 times closer to its star than the Earth is from the Sun.
However, since its host star, the red dwarf Gliese 581, is smaller and colder than the Sun – and thus less luminous – the planet lies in the habitable zone, the region around a star where water could be liquid!
“We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid,” said Stéphane Udry from the Geneva Observatory, Switzerland and lead-author of the paper in the journal Astronomy and Astrophysics.
“Moreover, its radius should be only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky – like our Earth – or covered with oceans,” he said.
“Liquid water is critical to life as we know it and because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X,” added Xavier Delfosse, a member of the team from Grenoble University, France.
According to the research team, the host star, Gliese 581, is among the 100 closest stars to us, located only 20.5 light-years away in the constellation Libra (“the Scales”).
The star has a mass only one third that of the Sun. Such red dwarfs are at least 50 times intrinsically fainter than the Sun and are the most common stars in our Galaxy. Among the 100 closest stars to the Sun, 80 belong to this class.
“Red dwarfs are ideal targets for the search for such planets because they emit less light, and the habitable zone is thus much closer to them than it is around the Sun. Any planets that lie in this zone are more easily detected with the radial-velocity method, the most successful in detecting exoplanets,” said Xavier Bonfils, a co-worker from Lisbon University.
Bureau Report
Actually it is. It just happens to have such a high eccentricity, the tidal lock is not a 1:1.
vp = sqrt(1.5*re*0.2*ae) = 0.55 * sqrt(re*ae)
Good idea, in priciple, but we might wanna check for babes before sending al.
mtg:
Habitable or not... could we just send all the liberals there?
I think the citizens there might NOT want LIBERALS there!! :)
Hmmm
Theoretically, an Orion Project-type ship could get there in about 25-40 years. More research should be made into the feasible of FTL travel, though.
Richard Bronson going to start service to it? LOL
Their football team would be AWESOME. ^_^
One of my favorite movies.
Loved her innocent look (and the short dress).
But we don’t have to worry about Al Gore activating the Krell machinery, because it reads brainwaves.
The big problem with this is that it’s so close to the red sun that the tidal pull would probably cause the same side of the planet to face the sun all of the time, much like the moon always has the same side to the earth. Thus, one side would be scortched, the other would be freezing.
Yep. Really heavy, sunburned, and getting no sleep ‘cause it never gets dark... I think I’ll stay here.
Have a great evening.
So, you're saying that if you were to dig a hole to within 10' of the center of the earth (allowing that you'd have to reinforce the walls), that the subjective force would be greater than at the surface? Yes, the total gravity exerting itself on you would be greater, but a portion (in this case, a large one) would be countered by opposing gravitational force. One isn't attracted by a center of gravity, but by each individual bit of mass in the universe, including the planet portions lateral to you and (in the example) above you. Gravimetric studies on Earth will sometimes make use of the effect by being conducted adjacent to large dense mountains.
As spunkets pointed out, the inverse square law applies.
While my skipping past my original off-the-cuff-statement referencing 5Gs may suggest otherwise, I agree. I was merely saying that it seemed incomplete.
It also doesn't matter that all planets are denser toward the center, than near the surface. Gravitational anomalies (masses at the same depth with different densities) have a slight effect, but they would not be noticable to you.
That does make it different, more like the idealized example I gave.
Rotation would also be insignificant, unless the planet has a very fast rotational velocity. On the Earth's Equator, you are travelling around the Earth at about 1,000 miles per hour, but you can stand at the Equator, or at one of the Poles, and not notice the difference in weight (you are slightly heavier at the Poles).
The rotation effect may indeed be important. What that rotation is at the stated distance from its star is largely dependent upon the age of the system - which I don't have the information to estimate. Large bodies close-in to other large bodies have a tendency to rotate surprisingly fast - potentially much faster than earth. On the other hand, in an old system, the planet could have transferred its rotational energy to its orbital energy in the same way that our Moon appears to have, making it tidally locked. Most probably it is somewhere in between. Where, I couldn't say.
This is simple Newtonian Statics and Dynamics, which is normally covered in the first quarter of college physics. Those who take physics in high school are likely to learn this before they get to college.
No need to get snooty, snippy, and snotty. My logic problem was much more fundemental than that: It's been a while since I formally studied physics and so I worked from a mental model of an idealized mass. The Earth and nearly all other significant bodies are spheroids or discs, so the issue I had in mind was already primarily taken into account.
That would indeed suggest that for a larger body generally the spin could indeed be much greater than for a smaller body...since if it's greater, the body would have less time to become tidally locked.
So...if this thing is rapidly rotating, and it has a nuclear core, along with the 13 day years for seasons, perhaps the estimate isn't too far-fetched, as its day/night temperatures would be less extreme than on earth (obviously the unknown atmosphere factors in), near the equator its gravity would be more reasonable, and it'd probably have a very powerful magnetic field to protect it from many of the solar effects.
That pic does look like the equitorial radius might be ~17% greater than the polar radius though. That’s if it’s a pic of the planet and it’s not been distorted by a pic edit. In that case, the gravitational force at the surface would be would be 1.8, instead of 2.2.
Granted the caveats, that's a huge difference. One that begins to put it down into the plausible range.
Yes, but there is no evidence that one can get the requisite extra negative mass to build the Alcubierre warp drive, or open a stable wormhole. The creation of negative mass (which does happen in certain quantum mechanical events) is always accompanied by the creation nearby of a larger positive mass.
No! Only the mass below you will contribute to the gravitational attraction, your weight would be nearly nothing. Isaac Newton proved this shortly after he invented calculus.
I don't have time to go through everything you've said, point by point. Suffice it to say that spunkets' answer was completely correct to two significant digits, which is perhaps a bit more precision than is justified by the data given.
If you really want to understand this, in detail, see if you can audit an astrophysics class at a good university.
Assuming no other differences, same volume and shape and 5*mass = 5Gs. however, if the size changes it roughly follows the inverse-square rule, with some minor modifications for distribution/shape and rotation effects in extreme circumstances. Above, Spunket suggests that if the picture of the planet is accurate, and that the distortion is caused by rotation effects that the rotation may reduce the subjective gravity by about 0.4Gs - which is some pretty extreme spinning.
The bones would also become denser as the microfracturing that goes on all the time normally would be enhanced and result in much heavier bones. Then you'd have more robust tendons and ligaments, and muscles, and so forth - all increasing your mass even further. Falling down would be more injurious, even with the stronger structure.
So what about Godebert's question? What effect would this have on atmospheric pressure, assuming an Earth-like atmosphere since it's supposed to be habitable.
The same amount of atmosphere would be more pressure, however the larger variant is simply how much atmoshpere there is. Take Venus, for example - its gravitational pull is much less than Earth's however its atmosphere is crushing as it simply has more atmosphere. What the increased gavity would do would be to make the habitable range much narrower by elevation than here on Earth, as the atmosphere would be squashed.
Based upon what was popping up at the end of GHWB's term, I'm surprised we don't have a half-kilometer synthetic aperture telescope in space by now. We'd be able to see continents.
Thanks for showing the math there.
Heh. I started from the opposite end - where what really matters is how much atmosphere there is to be exerted on.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.