[meteorite-list] A New Nearby Oddball Planet

Mon May 2 21:12:29 EDT 2011

Neophyte question again, from someone with a sharp interest and a lack of 
astophysic knowledge:

In short, how can we determine the density of a planet, other than ours and 
the locals...??  I can do it for gold-quartz samples (fortunately, the other 
reason for metal-detectors in the filed :>) )...but I need terrestrial 
gravity to pull it off.

Always ready for a lesson,
Richard Montgomery

----- Original Message ----- 
From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
To: "Meteorite List" <meteorite-list at meteoritecentral.com>
Sent: Monday, May 02, 2011 3:44 PM
Subject: [meteorite-list] A New Nearby Oddball Planet

> Back in January, there was a List discussion of a planet
> of the Kepler 10 (unnamed) star which has a density of
> 8.8, as heavy as iron and an argument about whether
> an entirely iron planet could exist and how.
>
> Now we have a (roughly) terrestial planet with a density
> of 11.0, or about the density of a solid lead ball... Iron
> ain't gonna do it.
>
> http://www.space.com/11544-densest-alien-planet-55cancrie.html
>
> Nearby Alien Planet Nearly Dense as Lead
>
> Astronomers have pinned down some details of an
> exotic nearby alien planet that's almost as
> dense as lead.
>
> The exoplanet, called 55 Cancri e, is 60 percent
> larger in diameter than Earth but eight times
> as massive, researchers revealed Friday (April 29).
> That makes the alien world the densest solid planet
> known -- twice as dense as Earth. [2 x 5.5 = 11.0]
>
> Astronomers previously thought 55 Cancri e took
> about 2.8 days to orbit its parent star. But the
> new study reveals that the exoplanet is so close
> to its host star that it completes a stellar lap
> in less than 18 hours.
>
> "You could set dates on this world by your wristwatch,
> not a calendar," study co-author Jaymie Matthews,
> of the University of British Columbia, said in a statement.
>
> Updating views of 55 Cancri e:
>
> The super-dense alien world is part of a multiplanet
> solar system about 40 light-years from Earth, in the
> constellation Cancer (The Crab). Its sunlike parent
> star, 55 Cancri, is bright enough to be seen from
> Earth by the unaided eye, researchers said.
>
> This wide-angle photograph of the night sky shows
> the location of 55 Cancri, a star where astronomers
> have found five planets, including a hot, dense
> super-Earth.
>
> This wide-angle photograph of the night sky shows
> the location of 55 Cancri, a star where astronomers
> have found five planets, including a hot, dense
> super-Earth.
>
> Since 1997, astronomers have discovered five planets
> circling 55 Cancri (including 55 Canrci e in 2004).
> All five alien worlds were detected using the so-called
> radial velocity -- or Doppler -- method, which looks
> for tiny wobbles in a star's movement caused by the
> gravitational tugs of orbiting planets.
>
> Initially, astronomers thought 55 Cancri e had an
> orbital period of about 2.8 days. But last year,
> two researchers -- Harvard grad student Rebekah
> Dawson and Daniel Fabrycky of the University of
> California, Santa Cruz -- re-analyzed the data.
> They suggested that the alien planet might actually
> zip around its host star much faster than that.
>
> So Dawson and Fabrycky joined up with a few others
> to observe 55 Cancri e more closely. The team trained
> Canada's MOST (Microvariability & Oscillations of STars)
> space telescope on the planet's star, then watched
> for the tiny brightness dips caused when 55 Cancri e
> passed in front of -- or transited -- it from the
> telescope's perspective.
>
> This is the same technique used by NASA's prolific
> Kepler space observatory, which has found 1,235
> alien planet candidates since its March 2009 launch.
>
> The team found that these transits occur like clockwork
> every 17 hours and 41 minutes, just as Dawson and
> Fabrycky had predicted. The starlight is dimmed by
> only 0.02 percent during each transit, telling the
> astronomers that the planet's diameter is about
> 13,049 miles (21,000 kilometers) -- only 60 percent
> or so larger than Earth.
>
> Using this information, the researchers were able to
> calculate 55 Cancri e's density.
>
> "It's wonderful to be able to point to a naked-eye
> star and know the mass and radius of one of its planets,
> especially a distinctive one like this," said study
> lead author Josh Winn of MIT.
>
> The research was released online Friday at the website
> arXiv.org, and it has been submitted for publication
> in The Astrophysical Journal Letters.
>
> A scorching-hot world
>
> Because 55 Cancri e is so close to its parent star,
> it wouldn't be a very pleasant place to live.
> Temperatures on its surface could be as high as
> 4,892 degrees Fahrenheit (2,700 degrees Celsius),
> researchers said.
>
> "Because of the infernal heat, it's unlikely that
> 55 Cancri e has an atmosphere," Winn said. "So this
> is not the type of place where exobiologists would
> look for life."
>
> If you could somehow survive the heat, however,
> the view from the planet's surface would be
> exotic and spectacular.
>
> "On this world -- the densest solid planet found
> anywhere so far, in the solar system or beyond -- 
> you would weigh three times heavier than you do
> on Earth," Matthews said. "By day, the sun would
> look 60 times bigger and shine 3,600 times brighter
> in the sky."
>
> But the appeal of 55 Cancri e is not limited to
> such gee-whiz factoids. Because it's so close to
> Earth, the planet and its solar system should
> inspire all sorts of future work, researchers said.
>
> "The brightness of the host star makes many types of
> sensitive measurements possible, so 55 Cancri e is
> the perfect laboratory to test theories of planet
> formation, evolution and survival," Winn said.
>
> ------------------------------------------------------------------------
>
> With a surface temperature of nearly 5000F (or ~2700K),
> this can't be a lead world -- it would have boiled away by
> now. A solid iron planet would just barely survive -- iron
> boils at 3134K.
>
> A planet of 75% iron with a 25% crust of Tungsten would
> have a density of 11, and I suppose that if everything less
> refractory than tungsten had boiled away, you could get
> such a planet...
>
> Here's everything heavier than iron and its density.
>
> I got tired of entering boiling points but you can see
> that the dense elements have high boiling points...
>
> Boiling points alone do not tell the story; vapor
> pressures are high above the melting point and
> such elements could slowly escape.
>
> Tungsten is the best bet. MP 3680K, BP 5828K.
> and moderately abundant in the universe, about
> like uranium.
>
> 76 Os Osmium  22.61 BP 5285K
> 77 Ir Iridium  22.56   BP 4701K
> 78 Pt Platinum  21.46   BP 5869K
> 75 Re Rhenium  21.02    BP 5869
> 93 Np Neptunium  20.45   BP 4273K
> 94 Pu Plutonium  19.84   BP 3501K
> 79 Au Gold  19.282   BP 3129K
> 74 W Tungsten  19.25   BP 5828K
> 92 U Uranium  18.95  BP 4404K
> 104 Rf Rutherfordium  18.1
> 73 Ta Tantalum 16.654   BP 5731K
> 91 Pa Protactinium  15.37
> 98 Cf Californium  15.1
> 97 Bk Berkelium  14.79
> 95 Am Americium  13.69
> 80 Hg Mercury  13.5336
> 96 Cm Curium  13.51
> 99 Es Einsteinium  13.5
> 72 Hf Hafnium  13.31
> 45 Rh Rhodium  12.41
> 44 Ru Ruthenium  12.37
> 46 Pd Palladium  12.02
> 81 Tl Thallium  11.85
> 90 Th Thorium  11.72
> 43 Tc Technetium  11.5
> 82 Pb Lead  11.342
> 47 Ag Silver  10.501
> 42 Mo Molybdenum  10.22
> 89 Ac Actinium  10.07
> 71 Lu Lutetium  9.84
> 83 Bi Bismuth  9.807
> 69 Tm Thulium  9.321
> 84 Po Polonium  9.32
> 68 Er Erbium  9.066
> 29 Cu Copper  8.96
> 28 Ni Nickel  8.912
> 27 Co Cobalt  8.86
> 67 Ho Holmium  8.795
> 48 Cd Cadmium  8.69
> 41 Nb Niobium  8.57
> 66 Dy Dysprosium  8.55
> 65 Tb Terbium  8.229
> 64 Gd Gadolinium  7.895
> 26 Fe Iron  7.874
>
> You put together a planet from the list...
>
>
> Sterling
>
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