Forgot your password?
typodupeerror
Space Science

Super-Earth Discovered In Star's Habitable Zone 135

Posted by samzenpus
from the big-house dept.
astroengine writes "The family of planets circling a relatively close dwarf star has grown to six, including a potential rocky world at least seven times more massive than Earth that is properly located for liquid water to exist on its surface, a condition believed to be necessary for life. Scientists added three new planets to three discovered in 2008 orbiting an orange star called HD 40307, which is roughly three-quarters as massive as the sun and located about 42 light-years away in the constellation Pictor. Of particular interest is the outermost planet, which is believed to fly around its parent star over 320 days, a distance that places it within HD 40307's so-called "habitable zone.""
This discussion has been archived. No new comments can be posted.

Super-Earth Discovered In Star's Habitable Zone

Comments Filter:
  • Fermi's p (Score:5, Funny)

    by harvey the nerd (582806) on Wednesday November 07, 2012 @11:40PM (#41915373)
    seven times more massive than Earth...
    so much for their early space program
    • Re:Fermi's p (Score:5, Informative)

      by NEDHead (1651195) on Wednesday November 07, 2012 @11:48PM (#41915409)

      Depends on the diameter and the rate of rotation.

      • Not so much. They say it's rocky and roughly liquid-water distance so it's probably close to Earth density, which limits the diameter. Spin rate might affect the perceived gravity but because of other factors is probably not very much of an issue.

        Most likely, surface gravity would be roughly 3 times Earth gravity.
        • Not really - the continents basically "float" on the mantle, so depending how hot it's core is that would affect how much pressure it exerted on the crust (and thus how wide it could be).

        • Re:Fermi's p (Score:5, Informative)

          by NEDHead (1651195) on Thursday November 08, 2012 @10:24AM (#41917989)

          Your math is a little off. If the density were the same as Earth's, the diameter would be proportional to the cube root of the mass ratios, or slightly less than 2 times that of Earth. The surface gravity is proportional to mass (7x) and inversely so to the square of the radius (~1/4) so 7/4 is about 1.75 surface gravity compared to Earth. If there were a comparable 'day' length, then the velocity at the equator would be about 2x that of Earth. An extra 1000 mph liftoff boost vs 1.75 local g, not so hard to overcome.

          And since we know nothing about the planet other than the mass, this is all silly speculation.

          • Thanks Sheldon....

          • by lgw (121541)

            Simple rule for SciFi RPG design: surface gravity is proportional to density times diameter. Easy to remember as the D&D rule.

          • Your math is a little off. If the density were the same as Earth's, the diameter would be proportional to the cube root of the mass ratios, or slightly less than 2 times that of Earth. The surface gravity is proportional to mass (7x) and inversely so to the square of the radius (~1/4) so 7/4 is about 1.75 surface gravity compared to Earth. If there were a comparable 'day' length, then the velocity at the equator would be about 2x that of Earth. An extra 1000 mph liftoff boost vs 1.75 local g, not so hard to

          • I used the formula from Wikipedia. I'll stick with that, thanks very much.
      • ..so maybe it's a mini-Mesklin [wikipedia.org]?

    • Re:Fermi's p (Score:5, Insightful)

      by macraig (621737) <mark DOT a DOT craig AT gmail DOT com> on Wednesday November 07, 2012 @11:53PM (#41915437)

      So they'll leapfrog straight to quantum teleportation, then?

      • by Lanteran (1883836)

        For the last time, quantum teleportation has nothing to do with moving things or people around instantly- obligatory xkcd [xkcd.com]. Most likely thing is that they use a project orion style system for launch- only realistic system I can think of to escape from a world with 300% earth gravity.

        • by macraig (621737)

          I said that instead of "teleporters" because I knew it would upset a physicist somewhere. :-)

    • Re:Fermi's p (Score:5, Interesting)

      by rossdee (243626) on Wednesday November 07, 2012 @11:54PM (#41915445)

      Just as well, because if they ever did get off their planet they would be able to beat us.
      (their ships would out maneuver ours , they would have faster reflexes, and we wouldn't have a chance in hand to claw combat

      • Just hit the little button on the back of the Sontarans' helmets and they go down like a sack of potatoes.
      • by wierd_w (1375923)

        Assuming they use extensible appendages for locomotion at all.

        At that level of local gravity, they are more likely to be something like a gastropod, or aquatic.

        pumping blood under 7 Gs is something human hearts require a pressure suit for! Any large bodied creatures from that planet would have to have a very different anatomic makeup from ours.

      • by Sperbels (1008585) on Thursday November 08, 2012 @01:38AM (#41915841)

        Just as well, because if they ever did get off their planet they would be able to beat us. (their ships would out maneuver ours , they would have faster reflexes, and we wouldn't have a chance in hand to claw combat

        Would they? Maybe their biochemistry makes it more efficient for them to have extremely slow reflexes. Maybe their movements would be as fast as grass growing. We could round up their entire invasion force and give them all anal probes and alien autopsies before they even knew what happened.

        • by Anonymous Coward on Thursday November 08, 2012 @06:11AM (#41916845)

          We could round up their entire invasion force and give them all anal probes and alien autopsies before they even knew what happened.

          I find your ideas intriguing and would like to subscribe to your newsletter.

      • by roc97007 (608802)

        Just as well, because if they ever did get off their planet they would be able to beat us.
        (their ships would out maneuver ours , they would have faster reflexes, and we wouldn't have a chance in hand to claw combat

        "But they die young, of heart problems"...

      • This is why we should all be training with weights in a knapsack.
      • by tgd (2822) on Thursday November 08, 2012 @09:04AM (#41917481)

        Just as well, because if they ever did get off their planet they would be able to beat us.
        (their ships would out maneuver ours , they would have faster reflexes, and we wouldn't have a chance in hand to claw combat

        And worst of all, their muscles are probably so dense, no amount of slow roasting will bring out any real flavor.

        • by rubycodez (864176)

          One word: Pâté

        • by Gilmoure (18428)

          In west Texas, they know how to bbq a tough brisket until it melts in your mouth. Just sayin.

          • by tgd (2822)

            In west Texas, they know how to bbq a tough brisket until it melts in your mouth. Just sayin.

            Of course, in West Texas, they don't really believe in science, so we may have a bit of an impasse.

      • by X0563511 (793323)

        Not necessarily. The things they could get into orbit would be smaller (because of that dang TWR) - though what they learn in getting it up there might exceed us, it would take them more effort to do something useful with it.

      • by mcgrew (92797) *

        You forget one salient point: they're only ten inches tall.

    • Re:Fermi's p (Score:5, Informative)

      by feedayeen (1322473) on Wednesday November 07, 2012 @11:54PM (#41915453)

      seven times more massive than Earth...

      so much for their early space program

      Assuming 2 planets have equal densities, Mass increases proportional to R^3, but gravity is proportional to the inverse squared of the distance.... As a result, surface gravity increases only linearly with the radius.... in this case, the planet would have 1.9 times the radius of the Earth if it's the same density.

      Earth has a very high density actually at 5.5g/cm3, it's actually the densest planetary object in our solar system. Most terrestrial objects are closer to 2 and the larger ones tend to be 3. It is entirely possible that it'll have a comparable surface gravity.

      • Re: (Score:3, Insightful)

        by Endovior (2450520)
        Good math, but you're ignoring the effect of mass on density. Earth is more dense than (for example) Mars because its greater mass results in more gravitational pressure, thus compressing its core, and increasing the density. There are limits, of course, and composition really does play a much bigger role than mass... hence why Mercury is the second densest planet in our system, despite being significantly less massive, and why gas giants have much lower densities, despite being vastly more massive. Even
        • Very true, there are other factors which may be contributing to our density like our lunar impactor which would have ejected lighter elements easier our our position in the accretion disk which would have provided us with supply of heavier raw elements. We also suspect that there's an upper limit for gas planets' volume based on gravitational collapse due to adding new material, one would expect a terrestrial analogue.

      • ...1.9 times the radius of the Earth...

        I believe a planet with 7.1 times the mass of Earth, assuming the same density, would only have 1.1923 times the radius of Earth. Check your math.

        • Re:Fermi's p (Score:5, Informative)

          by Bill Currie (487) on Thursday November 08, 2012 @05:14AM (#41916603) Homepage

          No, his math is quite correct: M=d*4*pi*r^3, so M(p)/M(e) = (d*4*pi*r(p)^3)/(d*4*pi*r(e)) which simplifies to r(p)^3/r(e)^3, or (r(p)/r(e))^3, thus the ratio is the cube-root of 7: 1.913 (or 7.1: 1.922). Still, 2G would be a cow for us.

          • by martinux (1742570)

            No, his math is quite correct: M=d*4*pi*r^3, so M(p)/M(e) = (d*4*pi*r(p)^3)/(d*4*pi*r(e)) which simplifies to r(p)^3/r(e)^3, or (r(p)/r(e))^3, thus the ratio is the cube-root of 7: 1.913 (or 7.1: 1.922). Still, 2G would be a cow for us.

            Hmmm, 3 digit ID and a comprehensive answer... sometimes correlation does imply causation!

          • by RockDoctor (15477)
            The bit about assuming the same density is the killer. The pressure deep in the Earth is sufficiently high that the mineralogy at depth is more dense than the mineralogy that is stable at the surface. If we *knew* what the mineralogy at depth was (we don't) and if we knew the equation of state for those minerals, at those pressures and temperatures, for exactly those compositions, then we could calculate the density at each pressure, and thus the exact relationship between mass and radius.

            What we can measu

    • by Aighearach (97333)

      seven times more massive than Earth...

      so much for their early space program

      And the green alien sex.

      • by Chrisq (894406)

        seven times more massive than Earth...

        so much for their early space program

        And the green alien sex.

        It might be OK still as long as they aren't on top

        • They're used to the gravity, you're not. They should be quite athletic by our standards and able to go all night, while you'd be wheezing just leaning against a poll.

    • Space program? So much for amoebas having the energy to move around.
      • by X0563511 (793323)

        I'm pretty sure that won't matter. Such a small (relatively) change of gravity really isn't going to matter for things at that scale.

    • by symbolset (646467) *
      A planet like that almost certainly has a moon of the correct size and composition. When we get to the stars we will find that almost all have homes for Men.
    • seven times more massive than Earth... so much for their early space program

      Maybe, or maybe they just develop different tech, space elevator maybe? [nasa.gov]

      • Afaict there are two big problems with the concept of the space elevator.

        One is materials, you need a material that is strong enough to support it's own weight without the CSA ratio* becoming insane.
        The other is how do you put the thing into place? Afaict the normal technique for reaching high orbits is to gradually increase the orbit but that won't work for a craft towing a space elevator cable (you'd wrap the cable round the planet) so you would need a rocket that could go "straight up" which aiui is much

        • Good points made, but the OPs point still holds. A rocket based space program would be significantly more resource hungry/expensive. I agree that a rocket would be necessary to install the elevator, but done right it could just be one rocket, with all subsequent payloads delivered by the elevator itself.

          It occurs to me that a race forced to make this their first step into space would have a distinct advantage when designing and building both their stellar and interstellar craft, in that they wouldn't be a

        • by lgw (121541)

          Actually, the big problem with a space elevator is that it will begin swinging uncontrollably if it lifts significant mass. At least for the Earth, getting into high orbit is about half overcoming grativational potential, and about half lateral acceleration. The elevator acts like a pendulum, but not an ideal frshman physics one, as the lateral force is applied gradually along it's length and the cable isn't rigid (and the orbital mechanics aren't quite the same as a pendulum). Each load you lifted would

          • Actually, the big problem with a space elevator is that it will begin swinging uncontrollably if it lifts significant mass.

            It is easy to show this is not true. The Tension is the cable is so massive the lateral forces from acceleration is more or less insignificant with tiny deflections only. You can even model the traveling waves these set up. Its not really a hard problem to deal with.

            • by lgw (121541)

              The tension in the cable makes no difference at all to the total energy put into the system, only in the form it takes - vibration of the cable, or motion of the counterweight. Unless you have some way to shed this energy (such as the heat from friction), it just keeps accumulating. And the tension on the cable depends on the orbital mechanics: when the counterweight takes an eliptical orbit, things start to get ugly.

              Conversation of angular momentum means the counterweight must "swing back" when a load is

              • I know my physics. The angular momentum is transferred to/from the earth when things go up/down. This was thought about way back when these things where proposed. Really its not even hard to model, there is even the odd analysis floating around the net. You don't need much damping either to make the system stable. Finding a cable that is strong enough is the hard part and remains the hard part.
    • by tgd (2822)

      seven times more massive than Earth...

      so much for their early space program

      Unless its covered in a form of plant life that absorbs, refines and aggregates Uranium, eventually ending up in small thermonuclear blasts used to spread their spores in a more effective way in the high gravity. Then the inhabitants can just collect up their nukkel fruits, and make their own Orion-type engines to get off the planet.

      It'd be a real blast.

    • by JCCyC (179760)
      Getting up in the morning must be a bitch.
  • Apostrophe! (Score:2, Insightful)

    by Dan East (318230)

    Star's, not stars', unless the planet is orbiting more than one star at a time. Didn't we just talk about apostrophe abuse in another Slashdot headline a couple days ago?

  • by l810c (551591) * on Wednesday November 07, 2012 @11:48PM (#41915415)

    But what about moons?

    We have found plenty of Jupiter size planets in the habitable zone.

    Imagine a planet larger than Jupiter with 60 moons orbiting in the habitable zone. Many with liquid water.

    I just marvel at the amount and diversity of moons in our own solar system. It seems like there would be far more moons in the habitable zone than planets universe wide.

    Hopefully in the future we'll build some giant telescope and get a better answer.

    • Re: (Score:1, Offtopic)

      by cameloid (120654)

      Yeah, but one of those "moons" is probably going to be a Death Star. More than likely there to keep the local governors in line, or something...

    • I have a gut felling that putting 60 earth sized objects in orbit around a Jupiter wouldn't work.
      Small planets don't fair that well... less you forget that our own moon is also in the 'habitable zone'

      • by wierd_w (1375923) on Thursday November 08, 2012 @02:11AM (#41915953)

        Just to play devil's advocate here.

        Let's assume that we have a neptune sized gas giant going through its daily grind around its parent star, and that it has a magnetosphere. (Only 1 in 50 red dwarf systems have a jupiter mass object in orbit, but 1 in 3 has a neptune mass object.)

        That close to its parent star, it would collect a tremendous amount of "cold" stellar plasma. (our little dirtball collects enough to create the van allen radiation belts. A neptune sized object would create a radiation torus MUCH larger.) This would inflate the magnetosphere to gargantuan proportions. This means that a great many of the proposed moons orbiting the gas giant would still retain thick atmospheres, unless other cosmic forces were actively at work to strip them. (like I think Enceladus's interaction with Saturn's magnetosphere...) Under such conditions, a rocky body like jupiter's moon Titan, which has a thick nitrogen and hydrocarbon atmosphere would be heated by both tidal heating, and be within the habitable zone. It would have an abundance of volcanic activity, and would get sufficient light that it could theoretically develop a biosphere.

        If you throw into the mix all the red dwarf stars in our local star cluster, and the shockingly large number of detected gas giant planets we have detected so far in "inner" solar system orbits, a solution to the problem of potentially habitable bodies in red dwarf systems becoming tide-locked is provided by moons orbiting habitable zone gas giants. Such systems would be well protected from meteor impacts, as the gas giant would sweep the vast majority of objects out of the orbital path of the pair. The gas giant would keep the rotation and orbital period of the moon on a nice even keel, and would provide a strong magnetosphere.

        If I were looking for a place to build a colony that could last a VERY VERY long time, I would look for goldilocks gas giants with habitable moons around red dwarf stars. The only niggly problem is the statistical scarcity of light elements like hydrogen in these systems. (M type stars are very rich in metals, but light on hydrogen and helium compared to more larger and more luminous stars. Any moons orbiting such gas giants are more likely to have an excessive amount of crustal oxygen than in other types of system, as metal oxide spectral lines are a mainstay feature of M type stars.) This might be resolvable if the system is "Absurdly old", as the high concentration of heavy elements would suggest a high level of radiological isotopes in the mineral composition of the planetary and satellite objects of such systems. This means that radiologically produced hydrogen from fission reactions over time could provide the missing hydrogen. M type star systems are quite capable of persisting to such advanced cosmic ages.

        I would be very interested in the prospect of habitable satellites of massive objects in red dwarf systems, and think that planets like ours get too much attention in the search for habitable bodies.

        • by Anonymous Coward

          One small correction if I may: Titan is a moon of Saturn, not Jupiter.

      • by mcgrew (92797) *

        Small planets don't fair that well

        Well, sure they do. We have two state fairs in Illinois, plus a fair for every county. It's probably like that in most states, and probably every country has a few good fairs. So I'd say Earth fairs VERY well.

        As to the moon, there are no fairs on the moon but it fares pretty well where it's sitting.

  • Gravity (Score:2, Interesting)

    by wisnoskij (1206448)

    I wonder if this will prevent walking animals.
    I imagine a snake or a fish should not have nearly as much trouble as a dog or human.

  • What's with the poor "Habitable Zone" being "So-Called"? That makes it sound like it's not the correct name for it, but being the correct scientific term, how can it be incorrect? Okay, maybe it's the "Circumstellar Habitable Zone" [wikipedia.org], but come on!!! It IS the theoretically "habitable zone" of a parent star, you could call it the so-called "Goldilocks Zone", because the phase "Goldilocks Zone" is just colloquial. /me ends rant.
    • What's with the poor "Habitable Zone" being "So-Called"? That makes it sound like it's not the correct name for it, but being the correct scientific term, how can it be incorrect? Okay, maybe it's the "Circumstellar Habitable Zone" [wikipedia.org], but come on!!! It IS the theoretically "habitable zone" of a parent star, you could call it the so-called "Goldilocks Zone", because the phase "Goldilocks Zone" is just colloquial. /me ends rant.

      I think "Goldilocks zone" is actually better, because it's the zone that's "just right". "Habitable" isn't a boolean proposition everywhere.

    • What's with the poor "Habitable Zone" being "So-Called"? That makes it sound like it's not the correct name for it

      Actually it's a way of specifying that it is the correct and recognised name for it, rather than a phrase a journo has come up with for the purposes of this article. I agree that it can be read as being dismissive of the term, as well.

  • Is this a dupe of yesterday's "we've now identified Krypton" story?

  • by roc97007 (608802) on Thursday November 08, 2012 @03:04AM (#41916135) Journal

    Just sayin'...

  • Wondering if this was Kobol'sstar?

    • by tgd (2822)

      Wondering if this was Kobol'sstar?

      No, Battlestar Galactica was a fictional story, not a documentary.

    • by whitroth (9367)

      No, it was Fortran

                    mark

  • by TyFoN (12980) on Thursday November 08, 2012 @08:03AM (#41917221)

    Maybe the answer is 42 :)
    BUT.
    42 light years at 10% of the speed of light (which is within the possibilities) and it would only take about 10 generations to reach this place.
    It could actually be a place suitable for evacuation!

    • by Metabolife (961249) on Thursday November 08, 2012 @10:02AM (#41917807)
      Who would want to spend their entire life in a small room surrounded by their parents? Oh wait.. this is /.
    • by CommieLib (468883)
      Less if they're being chased by sexy robots.
  • So, now we know where Valeria is.

              mark

  • With a declination of -60 degrees this is yet another intriguing nearby star system that is best viewed/targeted from the southern hemisphere. The Alpha Centauri system is only about 1 degree further south. It really seems that the southern sky is way more interesting than the north. Of course the galactic center and the Wow signal location are also in the southern hemisphere. It's good that the SKA is being built there. It's too bad that China's giant Arecibo-killer dish is not.

    This star would pass directl

While money doesn't buy love, it puts you in a great bargaining position.

Working...