[meteorite-list] OT: New Smallest, Possibly Earth-like,Extra-Solar Plane...

[Gerald Flaherty]

  But trying to find a nearby "invisible" star is a truly daunting technical 
problem
concerning which no light bulbs have turned on in my brain...  It's as dim 
in there as
the L dwarves themselves!


Sterling K. Webb
infared won't detect the L's??? Jerry Flaherty
----- Original Message ----- 
From: "Sterling K. Webb" <kelly at bhil.com>
To: <MexicoDoug at aol.com>
Cc: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, June 14, 2005 4:22 PM
Subject: Re: [meteorite-list] OT: New Smallest, Possibly 
Earth-like,Extra-Solar Plane...


> Hi,
>
>    My example of a SuperEarth was based on taking the same materials (bulk
> composition) as the Earth is made from and just piling more of them 
> together.  We have
> no idea (and no way of knowing, for now) if the planetesimals of the 
> Gliese 876 system
> were the same mix as the Sol planetesimals, but we think the raw materials 
> of solar
> systems are generally similar.
>    When I started suggesting the loss of some water so we could have 
> continents and a
> higher albedo so it would be cooler and so forth, you were being treated 
> to an ugly
> display of a rational mind crumbling under the pressures of "interstellar 
> optimism,"
> the desire to improve things just a touch.
>    After all, planetary systems have unique histories.  The Earth picked 
> up this
> whonking huge Moon to stabilize its axis and its climate though blind luck 
> at
> incredible odds.  Mars got all these volariles (we think) but then got its 
> atmosphere
> stripped off and died.  Venus really got a dirty deal; don't know what it 
> was, but it
> was nasty.  Them's the breaks.
>    It does make it look like there's more planetary bad luck than good 
> luck, doesn't
> it?  I'm sure we all wish Europa well!  And I have a soft spot in my head 
> for Titan.
> Always have had...
>    The interstellar "optimists" tend to think of extra-solar worlds as 
> similar to what
> we know, but 50-60 years ago the interplanetary "optimists" tended to 
> think of solar
> worlds as more Earth-like than they turned out to be.
>    As a teenager in the early Fifties, I devoured every scientific book on 
> other
> planets that there was, and the picture they presented was rosy compared 
> to reality,
> The very best book on Mars, "The Physics of the Planet Mars," by the great 
> Gerald de
> Vaucouleurs, was translated in English in 1953, a substantial tome filled 
> with
> equations, graphs, and tables.  I special ordered it, and it was damned 
> expensive.
>    It presented a Mars with an atmospheric pressure of 100 to 200 
> millibars and 85
> degree F. noonday temperatures.  All the astronaut would have to do was 
> slip on flight
> mask with a 10 pound oxygen tank on his back and go for a stroll.  He 
> could leave his
> leather jacket and white scarf back in the rocket because it's comfortable 
> weather out
> there, at least in the daytime.
>    The notions of Venus were rosier still.  It seems that the less you 
> know, the
> happier the picture you get.
>    Here's the kind of paradox that arises from "happy" thinking.  Venus 
> gets twice as
> much solar energy as the Earth.  But the albedo (reflectivity for those of 
> you
> listening in) of Venus is more than twice that of the Earth (as we 
> estimated the
> Earth's albedo in those days), so Venus shouldn't be any warmer than the 
> Earth (and a
> few brave souls even suggested it was cooler, with big polar ice caps)
>    In the 1940's, Rupert Wildt measured huge fat CO2 absorption features 
> in the Venus
> spectrum and concluded that Venus was a waterless inferno as hot as hell's 
> hinges.
> What he got for his suggestion was a lot of scowls and being ignored for a 
> decade or
> so.  Other scientists (big names and I ain't saying who) measured H2O 
> bands,  They were
> dead wrong about the water, because the water they were measuring was in 
> the atmosphere
> of Earth, not Venus!  Who knew?
>    So, Venus was maybe a little warm, very wet, always cloudy but bright, 
> kind of like
> the Permian had been on Earth.  Venus was so remarkably like the Earth on 
> paper that
> everyone figured it was the twin it appeared to be.  Probably had oxygen 
> under those
> clouds,  Get out of the spaceship, wear good boots (it was bound to be 
> muddy), and keep
> an eye out for Venusian dinosaurs.
>    I'm not talking about science fiction writers here; I'm talking about 
> real
> honest-to-gosh scientists.  We had gotten over Lowell and his canals on 
> Mars, but not
> by much.  Pickering was still talking about life on the Moon, for heaven's 
> sake.
> Although he had a great explanation for Martian canals: they were the 
> migratory routes
> of Martian herbivores, fertilized by their droppings.
>    Tommy Gold had his own special heresy for Venus (doesn't he always?), 
> an ocean of
> hydrocarbons, an idea that would get picked up from Venus and moved to 
> Titan for 30 or
> 40 years.  Ain't there.
>    You don't suppose wishful thinking has anything to do with the notion 
> of a
> planetary body with oceans of gasoline, do you?  Nah...  Sorry, no oceans 
> of free
> gasoline.  You can leave the SUV at home, buddy.
>    In some ways, science fiction writers could be more realistic than 
> scientists in
> those days.  Hal Clement (Harry Stubbs) wrote two novels about life on a 
> SuperJupiter
> around 61 Cyngi which are better pieces of rigorous thinking about these 
> really alien
> worlds than any scientific work that had been done on the question.  He 
> made me think
> about eutectic melts of ammonia and water in all its complexity until my 
> head really
> hurt. Of course, in those days, no one was doing scientific work on the 
> question.
>    Turns out the SuperJupiter around 61 Cyngi is really there!  Along with 
> scores of
> other SuperJupiters around other stars.
>    Even more fascinating is the possibility of other kinds of stars.  We 
> have always
> assumed that the tiniest faint dink of an M9 star is as small as "stars" 
> get.  Less
> mass and you get essentially non-luminous bodies:  brown dwarves, very 
> brown dwarves,
> and black dwarves.
>    But 2MASS (the Two Micron All Sky Survey) turned up huge numbers of 
> very, very
> faint stars never seen before, too faint to be seen in visible light. 
> About twenty of
> them have been assigned on their spectral characteristics to a new class 
> of stars: the
> Class L main sequence stars. About six are brown dwarves.  Since 2MASS 
> only sampled a
> very small patch of sky chosen at random and since their low emission sets 
> a limit to
> how far away we could detect these faintest of all stellar objects, we can 
> calculate
> their abundance.
>    The astounding answer is that they are more abundant than the M Class 
> stars that we
> used to think were the most abundant, so much so that the likelihood is 
> that there are
> about 2000 L Class main sequence stars within 50 light years of the Sun. 
> Yes, that's
> 2000 neighboring stars to our Sun that we can't even see in visible light!
> <http://astron.berkeley.edu/~basri/bdwarfs/sec4.htm>
> <http://astron.berkeley.edu/~basri/bdwarfs/sec6.htm>
>    That's an average of about one such star per 260 cubic light years. 
> Hmmm... What's
> the radius of a sphere with a volume of 260 cubic lightyears centered on 
> our Sun?  It's
> a shade less than the distance to the "nearest star," good old alpha 
> Centauri.  I put
> quotes around that phrase "nearest star" because, if 2MASS is right (and 
> it seems to
> be), there is a good chance there's an "invisible" star just as close or 
> closer to the
> Sun than that star we can see!
>    Really big bright stars don't seem to have planets.  They gobble up all 
> the planet
> food and blow off the rest; it too energetic an environment for a solar 
> system to form
> in.  We used to think low-mass stars, like M class, wouldn't have planets 
> because there
> wasn't enough mass around, but the detections of extra-solar planets seem 
> to indicate
> that the formation of a less energetic star leaves plenty of material left 
> over for
> planets.  Little Gliese 876 has two SuperJupiters!
>    So, following that line of reasoning, why wouldn't the new L Class 
> stars have lots
> of planets too?  Despite the fact that "happy" thinking would like alpha 
> Centauri to
> have planets because it's the closest, hence easiest, star to get to, no 
> detection
> attempt has ever found any hint of planets.  A closer L Class main 
> sequence star with
> planets would genuinely be worth looking for!
>    But trying to find a nearby "invisible" star is a truly daunting 
> technical problem
> concerning which no light bulbs have turned on in my brain...  It's as dim 
> in there as
> the L dwarves themselves!
>
>
> Sterling K. Webb
> ------------------------------------------------------
> MexicoDoug at aol.com wrote:
>
>> Hola Sterling,
>>
>> Your Super-Earth got me  thinking about viable life forms though I'm not 
>> yet
>> too adjusted.  There  certainly will be continents, though they will be
>> floating quagmires of life and  useful excreta, and will probably get 
>> quite thick.
>> Easily enough to walk  on, despite those who worry about finding a 
>> surface on
>> such gas-liquid giant  planets.  Not that walking will be too easy, so I 
>> guess
>> you would need  bigger muscles to deal with that.  The interesting thing 
>> with
>> such a world  is there would be several interfaces - multilevel 
>> continents -
>> especially  suitable as anchors (surfaces) for life depending on the 
>> vertical
>> profile of  gases and liquids present.  Gravity might be similar to that 
>> on
>> Earth  believe it or not, or even less in some of the upper level 
>> continents
>> since the  rarification will reduce the gravitational acceleration by the 
>> height
>> squared  (If you are on a planet 8 times the mass of earth but at 2.8X 
>> the
>> radius,  "surface gravity" is the same as Earth.)
>>
>> But you're right it would get  stuffy, so life would probably be pretty
>> acuatic-like and evolution driven by  the rise to an upper or lower 
>> continent in
>> addition to competition for low  hanging fruit resources.  There would 
>> probably
>> be heavy development using  bouyancy, and things would probably fly in 
>> that
>> fashion.  So the mosquitos  you would swat would land on you by 
>> regulating their
>> body densities with  intestinal waste gas.  Yuck.
>>
>> Dense Ice would be at least down where  pressures (and depths) were at 
>> 3000
>> atm, and very unstable given the dynamics of  the situation, it would be 
>> more
>> like a cloud formation, as probably not to  present much of an issue. 
>> But the
>> sort of magnetosphere this planet would  have...could metallic hydrogen 
>> make
>> it Earth-like?  Probably too  small.  It would be a pretty boring place, 
>> though
>> as meteorites would not  be much less likely  than on the surface of ...
>> Venus... so I guess these  water breathing nitrogen-fixing creatures 
>> would do
>> something else for kicks  (Starlight would not be very plentiful - and we 
>> need a
>> renewable energy source  or biosphere equilibrium with net energy going 
>> into
>> support the net entropy  production of the system).
>>
>> What I wonder is how the higher forms would  generate and harness 
>> electricity
>> for progress, considering the whole planet is  sounding rather grounded 
>> in a
>> lightening sauna?  It would make for a hell  of a set of oceanmill farms
>> working off the sea currents for anyone who could  come up with a good 
>> insulator...
>>
>> Saludos, Doug
>>
>> Sterling W.  wrote:
>> Hi,
>>
>> Is this an all time high or an all time  low?  I'm replying to
>> my own post (see below)!
>> While I don't have the most recent edition, I dug out my copy of
>> "Planetary  Engineers' Handbook" (Dresden, 15th Ed., 2314 AD) to
>> investiigate the  characteristics of a "SuperEarth."  Here's what
>> I  found:
>> So, what would a SuperEarth be like? If you start  with the
>> same recipe mix of ingredients as the Earth and just made  a
>> bigger batch of planet, is it just the same, only more so? Nope,
>> more of  the same is not the same.
>> If the Earth were bigger, it  would retain more volatiles to
>> begin with.  But in addition, the volume  of water would
>> increase faster than the increase in surface area, so  the
>> oceans would be deeper. Because of the deeper oceans and the
>> greater  gravity, the pressures at the bottoms of those oceans
>> would be much  higher.
>> Continents and their mountains would be much  lower, because
>> the temperatures in the crust would increase faster with  depth,
>> until the fluid point would be reached in the crust instead of
>> the  mantle like it is on "our" Earth. Mountains can only pile
>> up until the  pressures under them are about 3000 to 3500
>> atmospheres, and that zone would  be reached at shallower and
>> shallower depths on a bigger  Earth.
>> The solid crust of a larger "Earth" would be much  thinner,
>> heat transfer to the surface much faster, volcanism  much
>> livelier, plate tectonics much zippier.
>> Imagine an  "Earth" exactly twice the diameter of our Earth:
>> 16,000 miles across. It  would have four times the surface,
>> eight times the volume, and 12 times the  mass (compressibility
>> squishes). It's surface gravity would be 3 times  greater. The
>> escape velocity from the surface would 2.45 times  greater.
>> Because it would have 12 times the water but only  four
>> times the surface, the average ocean depth would be about  9000
>> meters! The pressure at the depths of these oceans would be
>> about  3000 atmospheres. The highest mountains possible would be
>> about 4000 meters  (calculating from the median diameter), so if
>> you were the greatest mountain  climber on the SuperEarth,
>> standing on the top of SuperEarth's highest  mountain, you would
>> have 5000 meters of water above  you!
>> Whoops! No continents. The SuperEarth is a  WaterWorld.
>> On our Earth, the crust is about 30 kilometers  thick, but
>> the lithosphere (rocks that stay stiff and not slushy  and
>> slippy) is about 75 kilometers, so the Earth's lithosphere
>> contains  all the crust and the top part of the mantle.
>> The crust of  the SuperEarth would be about 90 km thick, but
>> the lithosphere would only be  about 30 kilometers thick. This
>> means that it would be very difficult to sink  pieces of crust
>> (subduction) and equally difficult to bring deep basalt  magmas
>> to the surface.
>> On the other hand, the  SuperEarth's silicate crust would be
>> recylced very rapidly with lots of local  vulcanism and
>> "hotspots" and have a very similar composition everywhere.  The
>> only weathering that would be possible would be chemical,
>> because all  the volitiles are released into the oceans rather
>> than the  atmosphere.
>> The only question we can't answer is how hot  or cold a
>> SuperEarth would be, since that depends on the distunce to  its
>> Sun. Too far away and the oceans turn to ice, even Ice III,
>> which  sinks instead of rising.  Wow, did you know that?.
>> Too close and the oceans boil away, creating a
>> SuperVenus. But I discover  that making a Super Venus is
>> not as easy as it sounds.  It's very hard  to strip all that
>> atmosphere and immense oceans of volatiles away from  a
>> planet that has an escape velocity of 27,400 meters  per
>> second!
>> And remember, a SuperEarth would  have
>> proportionately more volatiles than a puny little Earth
>> like ours. It  could even afford to lose some of those
>> 9000 meters of ocean, don't you  think?  Maybe
>> enough to have continents?
>> Its  immense atmosphere would have a very high
>> albedo from a water cloud deck  100's of kilometers
>> deep, and the surface temperatures could well be  below
>> 100 degrees C.  Hmm, starting to sound interesting.
>> (Originally  posted to the List 08-31-2004 in anticipation
>> of the discovery of a  "SuperEarth," and Heck! I didn't
>> even have to wait a year... What  next?)
>>
>> Sterling K.  Webb
>> ------------------------------------------
>
>
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