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Super Earth reveals itself to Spitzer



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Title: Detection of Thermal Emission from a Super-Earth
Authors: Brice-Olivier Demory (MIT), Michael Gillon (University of Liege), Sara Seager (MIT), Bjoern Benneke (MIT), Drake Deming (University of Maryland), Brian Jackson (Carnegie)

We report on the detection of infrared light from the super-Earth 55 Cnc e, based on four occultations obtained with Warm Spitzer at 4.5 microns. Our data analysis consists of a two-part process. In a first step, we perform individual analyses of each dataset and compare several baseline models to optimally account for the systematics affecting each lightcurve. We apply independent photometric correction techniques, including polynomial detrending and pixel-mapping, that yield consistent results at the 1-sigma level. In a second step, we perform a global MCMC analysis including all four datasets, that yields an occultation depth of 13128ppm, translating to a brightness temperature of 2360300 K in the IRAC-4.5 micron channel. This occultation depth suggests a low Bond albedo coupled to an inefficient heat transport from the planetary dayside to the nightside, or else possibly that the 4.5-micron observations probe atmospheric layers that are hotter than the maximum equilibrium temperature (i.e., a thermal inversion layer or a deep hot layer). The measured occultation phase and duration are consistent with a circular orbit and improves the 3-sigma upper limit on 55 Cnc e's orbital eccentricity from 0.25 to 0.06.

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NASA's Spitzer Sees The Light of Alien 'Super Earth'

NASA's Spitzer Space Telescope has detected light emanating from a "super-Earth" planet beyond our solar system for the first time. While the planet is not habitable, the detection is a historic step toward the eventual search for signs of life on other planets.
The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a "supercritical" state where it is both liquid and gas, and topped by a blanket of steam

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First light from a super-Earth spotted

Scientists on a planetary-heat-seeking mission have detected the first infrared light from a super-Earth - in this case, a planet some 40 light-years away. And according to their calculations, 55 Cancri e, a planet just over twice the size of Earth, is throwing off some serious heat.
At a toasty 3,700 degrees Fahrenheit, the planet is hot enough to liquefy steel. And there's not much relief from the scorching heat: Researchers at MIT and other institutions say the planet may lack reflective surfaces such as ice caps, instead absorbing most of the heat from its parent star - much as Earth's dark oceans trap heat from the sun.

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It was initially unknown whether 55 Cancri e was a small gas giant like Neptune or a large rocky terrestrial planet. In 2011, a transit of the planet was confirmed, allowing to calculate its density. The high density calculated suggests that the planet has a "rock-iron composition supplemented by a significant mass of water, gas, or other light elements"
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Forty light years from Earth, a rocky world named "55 Cancri e" circles perilously close to a stellar inferno. Completing one orbit in only 18 hours, the alien planet is 26 times closer to its parent star than Mercury is to the Sun. If Earth were in the same position, the soil beneath our feet would heat up to about 3200 F. Researchers have long thought that 55 Cancri e must be a wasteland of parched rock.
Now they're thinking again. New observations by NASA's Spitzer Space Telescope suggest that 55 Cancri e may be wetter and weirder than anyone imagined.

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Supercritical water world does somersaults

Imagine that you are floating thousands of kilometres below the surface of a vast ocean that is neither liquid nor gas, but somewhere in between. Above you, the constellations very slowly shift and change as your watery world and its host star turn somersaults in space.
That's what you would see if you could swim on the planet 55 Cancri e, the most watery world discovered to date. New observations suggest that the planet is probably covered in so-called supercritical water, a kind of water that blurs the line between liquid and gas.
Not only that, but as the planet and its four planetary siblings orbit their host star, the whole system rotates in space due to tugs from a partner star, as if Saturn and its rings were turning on a spit.

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Title: 55 Cancri: A Coplanar Planetary System that is Likely Misaligned with its Star
Authors: Nathan A. Kaib, Sean N. Raymond, Martin J. Duncan

Although the 55 Cnc system contains multiple, closely packed planets that are presumably in a coplanar configuration, we use numerical simulations to demonstrate that they are likely to be highly inclined to their parent star's spin axis. Due to perturbations from its distant binary companion, this planetary system precesses like a rigid body about its parent star. Consequently, the parent star's spin axis and the planetary orbit normal likely diverged long ago. Because only the projected separation of the binary is known, we study this effect statistically, assuming an isotropic distribution for wide binary orbits. We find that the most likely projected spin-orbit angle is ~50 degrees, with a ~30% chance of a retrograde configuration. Transit observations of the innermost planet - 55 Cnc e - may be used to verify these findings via the Rossiter-McLaughlin effect. 55 Cancri may thus represent a new class of planetary systems with well-ordered, coplanar orbits that are inclined with respect to the stellar equator.

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Title: Improved precision on the radius of the nearby super-Earth 55 Cnc e
Authors: M. Gillon (1), B.-O. Demory (2), B. Benneke (2), D. Valencia (2), D. Deming (3), S. Seager (2), C. Lovis (4), M. Mayor (4), F. Pepe (4), D. Queloz (4), Damien Segransan (4), S. Udry (4) ((1) University of Liege, (2) MIT, (3) University of Maryland, (4) Observatory of the University of Geneva)

We report on new transit photometry for the super-Earth 55 Cnc e obtained with Warm Spitzer/IRAC at 4.5 microns. An individual analysis of these new data leads to a planet radius of 2.21-0.16+0.15 Earth radii, in good agreement with the values previously derived from the MOST and Spitzer transit discovery data. A global analysis of both Spitzer transit time-series improves the precision on the radius of the planet at 4.5 microns to 2.200.12 Earth radii. We also performed an independent analysis of the MOST data, paying particular attention to the influence of the systematic effects of instrumental origin on the derived parameters and errors by including them in a global model instead of performing a preliminary detrending-filtering processing. We deduce from this reanalysis of MOST data an optical planet radius of 2.040.15 Earth radii that is consistent with our Spitzer infrared radius. Assuming the achromaticity of the transit depth, we performed a global analysis combining Spitzer and MOST data that results in a planet radius of 2.170.10 Earth radii (13,820620 km). These results confirm that the most probable composition of 55 Cnc e is an envelope of supercritical water above a rocky nucleus.

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Spitzer Detects a Steaming Super-Earth Eclipsing Its Star

NASA's Spitzer Space Telescope has gathered surprising new details about a supersized and superheated version of Earth called 55 Cancri e. According to Spitzer data, the exoplanet is less dense than previously thought, a finding which profoundly changes the portrait of this exotic world. Instead of a dense rock scorched dry by its sun, 55 Cancri e likely has water vapour and other gases steaming from its molten surface.
Spitzer measured the extraordinarily small amount of light 55 Cancri e blocked when the planet crossed in front of its star. These mini-eclipses, called transits, allow astronomers to accurately determine a planet's size and calculate its density. Promisingly, the results show how astronomers can use Spitzer, operating in "warm" mode since depleting its liquid coolant in May 2009, to probe the properties of strange alien worlds.

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