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Earth's 'bigger cousin' detected

  1. Jun 13, 2005 #1

    Math Is Hard

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    SPACE.com -- Astronomers announced Monday the discovery of the smallest planet so far found outside of our solar system.

    About seven-and-a-half times as massive as Earth, and about twice as wide, this new extrasolar planet may be the first rocky world ever found orbiting a star similar to our own.

    "This is the smallest extrasolar planet yet detected and the first of a new class of rocky terrestrial planets," said team member Paul Butler of the Carnegie Institution of Washington. "It's like Earth's bigger cousin."

    http://www.cnn.com/2005/TECH/space/06/13/extrasolar.planet/index.html
     
  2. jcsd
  3. Jun 13, 2005 #2
    Wow - interesting stuff. Doesn't sound too hospitable though!
     
  4. Jun 13, 2005 #3

    tony873004

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    1.9 g surface gravity. It would be interesting how that would affect the development of life.
     
  5. Jun 13, 2005 #4

    Math Is Hard

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    We're starting to get really good at this extra-solar planet detection stuff!
    I am amazed at how much scientists can figure out from a little wobble. :cool:
     
  6. Jun 13, 2005 #5

    DaveC426913

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    A rocky planet, with 2G gravity, 15 light years away...

    That's WAY cool!
     
  7. Jun 14, 2005 #6

    marcus

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    smallest exoplanet around a main sequence star

    http://www.spaceref.com/news/viewnews.html?id=1031

    minimum mass 6 x earth.
    primary =Gliese 876
    red dwarf star about 1/3 mass of sun
    period of about 2 days (1.9 days)
    guessed to be rocky, but may have some atmosphere
    estim. temp. 400-700 fahrenheit

    http://www.universetoday.com/am/publish/large_rocky_planet.html?1362005

    http://skyandtelescope.com/news/article_1530_1.asp

    Here too is a BBC article
    http://news.bbc.co.uk/1/hi/sci/tech/4089534.stm

    too hot to live on, but hey, it is only 15 lightyears away!
     
  8. Jun 14, 2005 #7

    ohwilleke

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    Already covered in the Earth's bigger cousin thread. Ideally, the two should probably be merged.
     
  9. Jun 14, 2005 #8

    marcus

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    I found some more links about this exoplanet find.
    Here are some graphics
    http://exoplanets.org/gl876_web/gl876_graphics.html

    this includes a plot of data

    and two videos----a computer simulation of a flyby of the system and an overview of the system showing orbits of its three planets.

    and also it has some "artist conception" graphics of the system


    Here is a central website
    http://exoplanets.org/
    this site currently features links about Gliese 876

    NSF announcement
    http://nsf.gov/news/newsmedia/planetdiscovery.jsp
    NSF press release
    http://exoplanets.org/gl876_web/press_release_NSF.htm
    Technical data from the report submitted for publication
    http://exoplanets.org/gl876_web/gl876_tech.html

    Either way fine with me. I didnt see the other thread. basically I just want to put the links up in case a phrase like "lowest mass exoplanet" rings a bell for anyone and they should have some links to follow to find out more

    Whoah! here is a manuscript of the draft technical article they have submitted to Astrophysical Journal!
    the link is down at the bottom of the page here
    http://nsf.gov/news/newsmedia/planetdiscovery.jsp
    it says
    "Draft of the paper, A ~7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876"

    I tried downloading. So we can get the journal article itself, the day after it gets to popular media.

    this Gliese 876 system is interesting. It is real close to us: 15 lightyears. and also it is the lowest mass star known to harbor planets. It could be the destination of a probe some day. Like, not to this hot rock but to the two jupiters farther out.
     
    Last edited: Jun 14, 2005
  10. Jun 14, 2005 #9

    marcus

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    Wow! at least one of the other two planets might be a reasonable temperature!

    they would be "jupiters" (gas giants) but they could have moons like jupiter has moons

    the interesting thing is the wattage per square meter

    the luminosity of the star, Gliese 876, is 0.0124 of the Sun
    so about one percent of sun

    however the nearer of the two giants is at 0.10 AU
    so the "solar constant" there would be about 1.24 times earth
    which means the equilibrium temperature would be nearly the same as here at earth.

    the Harvard catalog is a good source of information, see
    http://cfa-www.harvard.edu/~planets/Gl876.html
     
  11. Jun 23, 2005 #10

    marcus

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    in another thread someone was talking about nearby habitable exoplanets

    and I think Gliese is interesting in that context because it has 3 planets, inner one too hot, outer one too cold but the middle planet
    has a "solar constant" (incoming radiant energy per unit time per unit area) about the same as the earth's

    I should say Gliese 876, not just Gliese

    anyway the middle planet (that is roughly the right temp) is a giant like jupiter which is a bit daunting, but it could have satellites like the jovian satellites (except they would have dried out because so much warmer, probably)

    it is only 15 lightyear off, so I'd say check it out. at one percent c it would only take 1500 years to get there---well? any thoughts?
     
  12. Jun 28, 2005 #11

    Nereid

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    Merged; thanks for the suggestion ohwilleke.
     
  13. Jun 28, 2005 #12
    Maybe you can sit in a space ship which can make fuel out of dark-matter and take a girl with yourself ( no harm intended if you are married ),20 generations later , you are there , wow!
     
  14. Jun 29, 2005 #13
    Why is 700 degrees f too hot? Can no life survive those temperatures, even alien life? Is there anything on Earth known to live through such heat?
     
  15. Jun 29, 2005 #14

    marcus

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    :smile:

    you are jumping ahead Dr. Brain.

    for starters people are going to study the Gliese 876 system intensively using telescopes groundbase and in orbit----it is a really interesting system with its 3 planets

    (I think the two jupitersize ones are in 2:1 resonance with period 30 days and 60 days)

    then quite possibly after a long time has passed and a lot has been learned about the system, people will want to send an unmanned probe.

    the main target of interest for the probe could be something in the system we do not know about yet, but it could also (I speculate) be the jupitersize planet with 30 day orbit that can be expected to be roughly
    SAME TEMPERATURE AS EARTH and which may have satellites

    even discounting the possibility that it has evolved life or even could support earthkind of life----even completely setting aside the life issue---this is one extremely interesting system. imagine a planet like jupiter but at about the same distance from the sun as earth is so that it is roughly earth temperature.

    actually a bit colder. the middle planet at Gliese 876 gets about 124/169 of the sunlight wattage per unit area that the earth does (according to harvard catalog numbers) and equilibrium temp would be about 92 percent of what it is at earth distance from sun-----so average temp could be below the H2O freezing point although midday temp could be melting. the harvard catalog data isnt really accurate enough to suppose much

    anyway this is a premier target for bigtime study, probably will be for centuries

    so let's figure out where it is in the sky!

    the magazine Sky and Telescope says this:

    The star itself is in easy reach of amateur telescopes. Using a detailed, large-scale star atlas, you can find it glowing orange at right ascension 22h 53m 13s, declination –14° 15' 13" (2000.0 coordinates). It's in the bottom of Aquarius's water bucket, as Sky & Telescope draws the constellation, ...
     
    Last edited: Jun 29, 2005
  16. Jun 29, 2005 #15
    I was talking about what we should do if we had to plan a manned flight to one of those planets.

    BJ
     
  17. Jun 29, 2005 #16

    marcus

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    I've been thinking about that, what you suggested. here is a webpage about the habitable-zone planet in that system

    the planet is called Gliese 876 C

    (I guess the primary is A and the planets are called B, C, and D
    B is too cold and D is too hot but C is about same temp as earth or a bit colder sometimes)

    http://www.extrasolar.net/planettour.asp?StarCatId=&PlanetId=156
     
  18. Jun 30, 2005 #17

    marcus

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    BTW here is a link to some information about another interesting system
    HD28185

    http://www.extrasolar.net/
    I cant get a direct link. only way I can see is to scroll down
    to where it says HD28185
    Oh wait, maybe this is a direct link
    http://www.extrasolar.net/startour.asp?StarCatID=normal&StarID=130
    http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=158

    another interesting one might be HD108874
    http://www.extrasolar.net/startour.asp?StarCatID=normal&StarID=159
    http://www.extrasolar.net/planettour.asp?StarCatId=normal&PlanetId=196
     
    Last edited: Jun 30, 2005
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