[meteorite-list] NEW EXOPLANET CoRoT-7b rocks!

[Sterling K. Webb]

Next another, slightly more detailed announcement
of the CoRoT-7b data:
http://www.sflorg.com/spacenews/sn091609_01.html

When I get data, I like to crunch it, and we have
enough for some solid nibbling on the new planet.

* The name of its star is TYC 4799-1733-1. (Needs
a sexier name than that.) It's a young star, only
about 1.5 billion years old. CoRoT-7b Is 23 times
closer to its star than Mercury is to our Sun. The
star, TYC 4799-1733-1, rotates once every 23 days,
very comparable to our Sun's rotation period. A
"normal" solar system, whatever that is.

* The planet has a diameter of about 14,000 miles
(and an equatorial circumference of 44,420 miles)
and a surface area 3.25 times that of Earth.

* It has an escape velocity of 26,400 m/sec (18.85
mi/sec) , or 2.36 times greater than Earth's escape
velocity. Leaving CoRoT-7b is a lot of work.

* The surface gravity is 1.543 times that of the
Earth's surface gravity, which would be survivable
if only the place weren't So Darned Hot.

* The CoRoT-7b "year" is only 20 hours 24 min. long.
It's probably safe to assume it always faces its Sun.
Or is it? We used to assume Mercury always showed
one face to the Sun, but it ain't necessarily so. If
CoRoT-7b is in a 3:2 resonance like Mercury, its
"day" would be 13 hours 36 min. long, which
would keep the surface uniformly toasty.

* It's only 2.5 million km (1.5 million miles) from
its star, so it's really hot -- 1000 C to 1500 C.

* The actual density of CoRoT-7b is 6.433 times
that of water because its immense mass crushes
its core to a high central density, but corrected
for compression, it's said to be 5.5, just like all
us Earths.

* Because of its size and mass, its crust will be
thin and plastic, with the lower crust probably
molten and liquid. It is doubtful that much surface
relief could be supported -- no high mountains,
although the higher gravity will give them steeper
outlines.  The thin crust will easily sink anywhere,
even though it won't sink fast. The crust should
be young and well-mixed with little compositional
differences.

* Its atmosphere is anybody's guess. It could be
metallic and heavier element vapors. It could be
high pressure steam, very deep, with an albedo
of 0.93 over deep H20 oceans, although it's hard
to see how it could retain water that close to its
star, even for a mere 1.5 billion years and despite
the fact that if it had the same percentage of water
in its makeup as the Earth, its surface oceans
would be 60% deeper than Earth's oceans.
Atmospheric guessing is really unreliable.

* It makes the our Venus's Hell look like an air-
conditioned tropical paradise by comparison...


Sterling K. Webb
------------------------------------------------------------------
----- Original Message ----- 
From: "Darren Garrison" <cynapse at charter.net>
To: <Meteorite-list at meteoritecentral.com>
Sent: Wednesday, September 16, 2009 12:21 PM
Subject: [meteorite-list] CoRoT-7b rocks!


http://spacefellowship.com/2009/09/16/smallest-exoplanet-is-shown-to-be-a-solid-rocky-world/

Smallest exoplanet is shown to be a solid, rocky world
Published By
Matt
On: 16 September 2009 11:26 AM CEST  Source

The confirmation of the nature of CoRoT-7b as the first rocky planet 
outside our
Solar System marks a significant step forward in the search for 
Earth-like
exoplanets. The detection by CoRoT and follow-up radial velocity 
measurements
with HARPS suggest that this exoplanet, CoRoT-7b, has a density similar 
to that
of Mercury, Venus, Mars and Earth making it only the fifth known 
terrestrial
planet in the Universe.

The search for a habitable exoplanet is one of the holy grails in 
astronomy. One
of the first steps towards this goal is the detection of terrestrial 
planets
around solar-type stars. Dedicated programmes, using telescopes in space 
and on
ground, have yielded evidence for hundreds of planets outside of our 
Solar
System. The majority of these are giant, gaseous planets, but in recent 
years
small, almost Earth-mass planets have been detected demonstrating that 
the
discovery of Earth analogues - exoplanets with one Earth mass or one 
Earth
radius orbiting a solar-type star at a distance of about 1 astronomical 
unit -
is within reach.

Transit detections yield key physical properties

A number of techniques are routinely employed in the search for 
exoplanets:
spectroscopic radial velocity, astrometry, microlensing, photometric 
transits.
Of these, the search for transits - the passage of the exoplanet in 
front of the
parent star - provides unprecedented access to the planet's physical 
properties.
In particular, the combination of transit photometry and radial velocity
measurements provides direct and very accurate estimates of the 
planetary mass
and radius, and hence mean density. These parameters in turn provide 
tight
constraints on the composition and physical structure of the planet and 
hence on
the likelihood of the exoplanet being a true Earth analogue.

The CoRoT space mission employs the transit strategy in the search for
exoplanets. Continuous observations, lasting about 150 days each, are 
made of
two large (4 square degrees) regions towards the centre and anti-centre 
of the
Galaxy. During the first of these observation periods towards the 
anti-centre
(October 2007 to March 2008), 46 stars exhibited evidence for transits, 
among
them CoRoT-7, a main-sequence, close-by (at a distance of 150 pc) 
solar-type
star.

The size is determined with photometry from CoRoT .

Investigation of the data, as described by Alain Léger and colleagues, 
provided
compelling evidence for the presence of an exoplanet. The discovery was
announced earlier this year at which time the analysis of CoRoT data had 
shown
that CoRoT-7b (as the planet is known) has a diameter less than twice 
that of
Earth making it the smallest exoplanet (to date) orbiting a 
main-sequence star.
The CoRoT data also demonstrated that the planet is about 2.5 million km 
from
its parent star and orbits once every 20.4 hours.

. and HARPS radial velocity measurements provide the mass

Further progress, and in particular the determination of the planet 
mass, could
only be made by obtaining accurate measurements of the variation in the 
velocity
of the star caused by the gravitational pull of the orbiting planet. The 
need
for ground-based support observations for CoRoT had always been 
envisaged and
time on the HARPS spectrograph (at the ESO 3.6-m telescope at La Silla 
in Chile)
had been secured as a result of an ESA call for European 
co-investigators for
CoRoT. Didier Queloz and colleagues describe how almost 70 hours of 
observations
of the CoRoT-7 system with HARPS finally provided the sought-after 
result:
CoRoT-7b is one of the lightest exoplanets detected to date with a mass 
five
times that of the Earth. This puts CoRoT-7b firmly in the category of
"super-Earth" - an exoplanet with a mass between that of Earth and gas 
giants.

A terrestrial exoplanet orbiting a solar-type star

Although about a dozen super-Earths have been detected CoRoT-7b is the 
first for
which both mass and radius estimates are available. Combining the radius
estimates from CoRoT and the mass estimates from HARPS results in an 
exoplanet
mean density of 5.5 g/cm3.   There are only three other known planets 
with
similar density: Earth, Mercury and Venus (Mars is less dense) which 
strongly
suggests that the planet is a solid, rocky planet.

"We are coming tantalising close to reaching the ultimate goal of 
detecting a
true Earth-like planet," comments Malcolm Fridlund, ESA CoRoT Project 
Scientist
and member of the CoRoT Science Team. "This bodes well for future 
exoplanet
search missions, such as the Cosmic Vision candidate, PLATO."

About CoRoT

CoRoT is a mission led by the French national space agency, CNES. ESA 
has joined
the mission by providing the optics and baffle for the telescope and 
testing of
the payload. Through this collaboration a number of European scientists, 
from
Denmark, Switzerland, the United Kingdom and Portugal, have been 
selected as
Co-Investigators in open competition. As a result of ESA's participation 
in
CoRoT, scientists from ESA's Member States have access to the 
satellite's data.

ESA's Research and Scientific Support department (RSSD) at ESTEC is a 
full
partner in CoRoT by providing the on-board Data Processing Units 
(DPU's). Other
partners in CoRoT are Austria, Spain, Germany, Belgium and Brazil.

The ESA PRODEX programme has supported the development of the CoRoT 
telescope
baffle, and the software development and data processing of CoRoT light 
curves.

The ground stations used for CoRoT are located in Kiruna (S), Aussaguel 
(F)
Hartebeesthoek (South Africa), Kourou (French Guyana), with 
mission-specific
ground stations in Alcantara (Brazil) and Vienna (A).
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