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"Earth-like Planets May Have Formed Early in Milky Way's History" --With Implica

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  • derhexerus
    An interesting post from The Daily Galaxy. If true, where are they? Chris ____________________________________ From: vlandi@yahoo.com To: derhexer@aol.com
    Message 1 of 1 , Apr 14, 2013
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      An interesting post from The Daily Galaxy. If true, where are they?


      From: vlandi@...
      To: derhexer@...
      Sent: 4/14/2013 6:26:09 P.M. Eastern Daylight Time
      Subj: The Daily Galaxy: News from Planet Earth & Beyond

      _The Daily Galaxy: News from Planet Earth & Beyond_


      _"Earth-like Planets May Have Formed Early in Milky Way's History" --With
      Implications for Advanced Life_
      Posted: 14 Apr 2013 07:32 AM PDT


      Building a _terrestrial planet_
      (http://en.wikipedia.org/wiki/Terrestrial_planet) requires raw materials that weren't available in the early history
      of the universe. The Big Bang filled space with hydrogen and helium.
      Chemical elements like silicon and oxygen - key components of rocks - had to be
      cooked up over time by stars. But how long did that take? How many of such
      _heavy elements_ (http://en.wikipedia.org/wiki/Heavy_metal_(chemistry)) do
      you need to form planets?Earlier studies have shown that Jupiter-sized gas
      giants tend to form around stars containing more heavy elements than the
      Sun. However, research by a team of astronomers found that planets smaller
      than Neptune are located around a wide variety of stars, including those with
      fewer heavy elements than the Sun. As a result, rocky worlds like Earth
      could have formed earlier than expected in the universe's history.
      "This work suggests that terrestrial worlds could form at almost any time
      in our galaxy's history," said Smithsonian astronomer David Latham
      (_Harvard-Smithsonian Center for Astrophysics_
      (http://maps.google.com/maps?ll=42.38146,-71.12837&spn=0.01,0.01&q=42.38146,-71.12837 (Harvard–
      Smithsonian%20Center%20for%20Astrophysics)&t=h) ). "You don't need many earlier generations
      of stars."* Latham played a lead role in the study, which was led by Lars A.
      Buchhave from the University of Copenhagen.* Astronomers call chemical
      elements heavier than hydrogen and helium "metals."
      They measure the metal content, or metallicities, of other stars using the
      Sun as a benchmark. Stars with more heavy elements are considered
      _metal-rich_ (http://en.wikipedia.org/wiki/Metallicity) while stars with fewer
      heavy elements are considered metal-poor.
      In 2012, Latham and his colleagues examined more than 150 stars known to
      have planets, based on data from NASA's _Kepler spacecraft_
      (http://kepler.nasa.gov/) . They measured the stars' metallicities and correlated that with
      the sizes of the associated planets. Large planets tended to orbit stars
      with solar metallicities or higher. Smaller worlds, though, were found around
      metal-rich and metal-poor stars alike.* "_Giant planets_
      (http://en.wikipedia.org/wiki/Gas_giant) prefer metal-rich stars. Little ones don't,"
      explained Latham.
      They found that terrestrial planets form at a wide range of metallicities,
      including systems with only one-quarter of the Sun's metal content. *
      Their discovery supports the "core accretion" model of planet formation. In
      this model, primordial dust accumulates into mile-sized planetesimals that
      then coalesce into full-fledged planets. The largest, weighing 10 times Earth,
      can then gather surrounding hydrogen and become a gas giant.
      A gas giant's core must form quickly since hydrogen in the protoplanetary
      disk dissipates rapidly, swept away by stellar winds in just a few million
      years. Higher metallicities might support the formation of large cores,
      explaining why we're more likely to find a gas giant orbiting a metal-rich
      star."This result fits with the core accretion model of planet formation in a
      natural way," said Latham.
      The Daily Galaxy via _Harvard-Smithsonian Center for Astrophysics _
      Image credit: With thanks, _http://deviously-buzzkilled.deviantart.com_
      (http://deviously-buzzkilled.deviantart.com/) Related articles

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      Best Potential to Identify Twin Earths_

      (http://www.dailygalaxy.com/my_weblog/2013/03/globular-cluster-found-harboring-a-13-billion-year-old-planet-weekend-feature.html) _Globular Cluster
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      (http://www.dailygalaxy.com/my_weblog/2013/03/origin-of-jupiter-and-saturn-new-theories.html) _Origin of Jupiter and Saturn --New Theories on
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      _Exo-Planet Names Not for Sale Warns IAU_
      Posted: 14 Apr 2013 08:54 AM PDT

      Beware --alien planet names not for sale _International Astronomical Union
      (IAU)_ (http://www.iau.org/) warns. More than 2000 planets outside the
      _Solar System_ (http://en.wikipedia.org/wiki/Solar_System) have been found to
      date, with more waiting to be confirmed. Detection methods in this field
      are steadily and quickly increasing—meaning that many more exoplanets will
      undoubtedly be discovered in the months and years to come.Recently, an
      organisation has invited the public to purchase both nomination proposals for
      exoplanets, and rights to vote for the suggested names. In return, the
      purchaser receives a certificate commemorating the validity and credibility of
      the nomination. Such certificates are misleading, as these campaigns have no
      bearing on the official naming process—they will not lead to an
      officially-recognised exoplanet name, despite the price paid or the number of votes
      accrued. * Upon discovery, exoplanets and other astronomical objects receive
      unambiguous and official catalogue designations. While exoplanet names such
      as _16 Cygni Bb_ (http://en.wikipedia.org/wiki/16_Cygni_Bb) or _HD 41004
      Ab_ (http://en.wikipedia.org/wiki/HD_41004_Ab) may seem boring when
      considering the _names of planets_ (http://en.wikipedia.org/wiki/Planet) in our own
      Solar System, the vast number of objects in our Universe—galaxies, stars,
      and planets to name just a few—means that a clear and systematic system for
      naming these objects is vital. Any naming system is a scientific issue
      that must also work across different languages and cultures in order to
      support collaborative worldwide research and avoid confusion. * To make this
      possible, the IAU acts as a single arbiter of the naming process, and is
      advised and supported by astronomers within different fields. As an
      international scientific organisation, it dissociates itself entirely from the
      commercial practice of selling names of planets, stars or or even "real estate" on
      other planets or moons. These practices will not be recognised by the IAU
      and their alternative naming schemes cannot be adopted. However, the IAU
      greatly appreciates and wishes to acknowledge the increasing interest from the
      general public in being more closely involved in the discovery and
      understanding of our Universe. *As a result in 2013 the IAU Commission 53
      _Extrasolar Planets_ (http://en.wikipedia.org/wiki/Extrasolar_planet) and other IAU
      members will be consulted on the topic of having popular names for
      exoplanets, and the results will be made public on the IAU website. Meanwhile,
      astronomers and the public are encouraged to keep using the existing accepted
      nomenclature—details of which can be found on the Astronomy for the Public
      section of the IAU web page, under Naming _Astronomical Objects_
      (http://en.wikipedia.org/wiki/Astronomical_object) . *The Daily Galaxy via
      International Astronomical Union Related articles

      (http://www.dailygalaxy.com/my_weblog/2013/03/lost-planets-could-be-as-numerous-as-stars-weekend-feature.html) _Lost Planets --"Could be as Numerous
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      (http://www.dailygalaxy.com/my_weblog/2013/03/colossal-star-system-discovered-may-harbor-earth-like-planets-.html) _Colossal Star System Discovered
      --"May Harbor Earth-like Planets"_

      (http://www.dailygalaxy.com/my_weblog/2013/02/very-large-telescope-captures-1st-proto-planet-candidate-a-key-to-our-cosmic-origins.html) _'Very Large
      Telescope' Captures 1st Proto-Planet Candidate--"A Key to Our Cosmic


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