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Post Info TOPIC: CoRoT-Exo-1b


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Posts: 131433
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CoRoT Sol 1
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Title: The future of the Sun: an evolved solar twin revealed by CoRoT
Authors: J.-D. do Nascimento Jr., Y. Takeda, J. Melendez, J.S. da Costa, G.F. Porto de Mello, M. Castro

The question of whether the Sun is peculiar within the class of solar-type stars has been the subject of active investigation over the past three decades. Although several solar twins have been found with stellar parameters similar to those of the Sun (albeit in a range of Li abundances and with somewhat different compositions), their rotation periods are unknown, except for 18 Sco, which is younger than the Sun and with a rotation period shorter than solar. It is difficult to obtain rotation periods for stars of solar age from ground-based observations, as a low activity level imply a shallow rotational modulation of their light curves. CoRoT has provided space-based long time series from which the rotation periods of solar twins as old as the Sun could be estimated. Based on high S/N high resolution spectroscopic observations gathered at the Subaru Telescope, we show that the star CoRoT ID 102684698 (CoRoT Sol 1) is a somewhat evolved solar twin with a low Li abundance. Its rotation period is 29 ± 5 days, compatible with its age (6.7 Gyr) and low lithium content A(Li) < 0.85 dex. Interestingly, our CoRoT solar twin seems to have enhanced abundances of the refractory elements with respect to the Sun, a typical characteristic of most nearby twins. With a magnitude V ~14.1, ID 102684698 is the first solar twin revealed by CoRoT, the farthest field solar twin so far known, and the only solar twin older than the Sun for which a rotation period has been determined.

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Position (J2000): R.A. 06 48 19.17  |  Dec. -03° 06' 07.68''



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Posts: 131433
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RE: CoRoT-Exo-1b
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Title: Ground-based detections of thermal emission from CoRoT-1b and WASP-12b
Authors: Ming Zhao (1), John D. Monnier (2), Mark R. Swain (1), Travis Barman (3), Sasha Hinkley (4) ((1) Jet Propulsion Lab, (2) University of Michigan, (3) Lowell Observatory, (4) California Institute of Technology)

We report a new detection of the H-band thermal emission of CoRoT-1b and two confirmation detections of the Ks-band thermal emission of WASP-12b at secondary eclipses. The H-band measurement of CoRoT-1b shows an eclipse depth of 0.145% ±0.049% with a 3-{\sigma} percentile between 0.033% - 0.235%. This depth is consistent with the previous conclusions that the planet has an isother- mal region with inefficient heat transport from dayside to nightside, and has a dayside thermal inversion layer at high altitude. The two Ks band detections of WASP-12b show a joint eclipse depth of 0.299% ±0.065%. This result agrees with the measurement of Croll & collaborators, providing independent confirmation of their measurement. The repeatability of the WASP-12b measurements also validates our data analysis method. Our measurements, in addition to a number of previous results made with other telescopes, demonstrate that ground-based observations are becoming widely available for characterization of atmospheres of hot Jupiters.

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Posts: 131433
Date:
CoRoT-1
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Title: Warm Spitzer Photometry of the Transiting Exoplanets CoRoT-1 and CoRoT-2 at Secondary Eclipse
Authors: Drake Deming, Heather Knutson, Eric Agol, Jean-Michel Desert, Adam Burrows, Jonathan J. Fortney, David Charbonneau, Nicolas B. Cowan, Gregory Laughlin, Jonathan Langton, Adam P. Showman, Nikole K. Lewis

We measure secondary eclipses of the hot giant exoplanets CoRoT-1 at 3.6 and 4.5 microns, and CoRoT-2 at 3.6 microns, both using Warm Spitzer. We find that the Warm Spitzer mission is working very well for exoplanet science. For consistency of our analysis we also re-analyse archival cryogenic Spitzer data for secondary eclipses of CoRoT-2 at 4.5 and 8 microns. We compare the total data for both planets, including optical eclipse measurements by the CoRoT mission, and ground-based eclipse measurements at 2 microns, to existing models. Both planets exhibit stronger eclipses at 4.5 than at 3.6 microns, which is often indicative of an atmospheric temperature inversion. The spectrum of CoRoT-1 is best reproduced by a 2460K blackbody, due either to a high altitude layer that strongly absorbs stellar irradiance, or an isothermal region in the planetary atmosphere. The spectrum of CoRoT-2 is unusual because the 8 micron contrast is anomalously low. Non-inverted atmospheres could potentially produce the CoRoT-2 spectrum if the planet exhibits line emission from CO at 4.5 microns, caused by tidal-induced mass loss. However, the viability of that hypothesis is questionable because the emitting region cannot be more than about 30-percent larger than the planet's transit radius, based on the ingress and egress times at eclipse. An alternative possibility to account for the spectrum of CoRoT-2 is an additional opacity source that acts strongly at wavelengths less than 5 microns, heating the upper atmosphere while allowing the deeper atmosphere seen at 8 microns to remain cooler. We obtain a similar result as Gillon et al. for the phase of the secondary eclipse of CoRoT-2, implying an eccentric orbit with e*cos(omega)=-0.0030 ±0.0004.

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Title: The spin-orbit angle of CoRoT-1: evidence for a strongly misaligned hot Jupiter
Authors: F. Pont, M. Endl, F. Bouchy, S. Aigrain, C. Moutou, R. Alonso, A. Baglin, M. Fridlund, A. P. Hatzes, G. Hebrard, W. D. Cochran, S. I. Barnes, C. Sneden, P. J. MacQueen

We measure the angle between the planetary orbit and the stellar rotation axis in the transiting planetary system CoRoT-1, with HIRES/Keck and HARPS radial-velocity spectroscopy, and FORS/VLT high-accuracy photometry. The data indicate a highly tilted system, with a projected spin-orbit angle lambda = 77 ±11 degrees (systematic uncertainties in the radial velocity data could cause the actual error to be larger).
Spin-orbit alignment has now been measured in a dozen extra-solar planetary systems, and several shown strong misalignment. The first three misaligned planets were all much more massive than Jupiter and followed eccentric orbits. CoRoT-1, however, is a jovian-mass close-in planet on a circular orbit. The high occurrence of misaligned systems for several types of planets and orbits favours planet-planet scattering as a mechanism to bring gas giants on very close orbits. Our extensive radial-velocity monitoring of CoRoT-1 excludes the presence of another gas giant planet in the system out to about 2 AU.

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Posts: 131433
Date:
CoRoT-1b
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Title: The secondary eclipse of CoRoT-1b
Authors: R. Alonso, A. Alapini, S. Aigrain, M. Auvergne, A. Baglin, M. Barbieri, P. Barge, A.S. Bonomo, P. Borde, F. Bouchy, S. Chaintreuil, R. De la Reza, H.J. Deeg, M. Deleuil, R. Dvorak, A. Erikson, M. Fridlund, F. Fialho, P. Gondoin, T. Guillot, A. Hatzes, L. Jorda, H. Lammer, A. Leger, A. Llebaria, P. Magain, T. Mazeh, C. Moutou, M. Ollivier, M. Patzold, F. Pont, D. Queloz, H. Rauer, D. Rouan, J. Schneider, G. Wuchterl

The transiting planet CoRoT-1b is thought to belong to the pM-class of planets, in which the thermal emission dominates in the optical wavelengths. We present a detection of its secondary eclipse in the CoRoT white channel data, whose response function goes from ~400 to ~1000 nm. We used two different filtering approaches, and several methods to evaluate the significance of a detection of the secondary eclipse. We detect a secondary eclipse centred within 20 min at the expected times for a circular orbit, with a depth of 0.016±0.006%. The center of the eclipse is translated in a 1-sigma upper limit to the planet's eccentricity of ecosomega<0.014. Under the assumption of a zero Bond Albedo and blackbody emission from the planet, it corresponds to a T_{CoRoT}=2330 +120-140 K. We provide the equilibrium temperatures of the planet as a function of the amount of reflected light. If the planet is in thermal equilibrium with the incident flux from the star, our results imply an inefficient transport mechanism of the flux from the day to the night sides.

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Title: VLT transit and occultation photometry for the bloated planet CoRoT-1b
Authors: M. Gillon (1 and 2), B.-O. Demory (2), A.H.M.J. Triaud (2), T. Barman (3), L. Hebb (4), J. Montalban (1), P.F.L. Maxted (5), D. Queloz (2), M. Deleuil (6), P. Magain (1) ((1) IAGL, Universite de Liege, Belgium, (2) Observatoire de Geneve, Switzerland, (3) Lowell Observatory, USA, (4) School of Physics and Astronomy, University of St. Andrews, UK, (5) Astrophysics Group, Keele University, UK, (6) LAM, Marseille, France)

We present VLT eclipse photometry for the giant planet CoRoT-1b. We observed a transit in the R-band filter and an occultation in a narrow filter centred on 2.09 microns. Our analysis of this new photometry and published radial velocities, in combination with stellar-evolutionary modelling, leads to a planetary mass and radius of 1.07 (+0.13,-0.18) M_Jup and 1.45 (+0.07,-0.13) R_Jup, confirming the very low density previously deduced from CoRoT photometry. The large occultation depth that we measure at 2.09 microns (0.278 (+0.043,-0.066) %) is consistent with thermal emission and is better reproduced by an atmospheric model with no redistribution of the absorbed stellar flux to the night side of the planet.

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A super-hot planet 1500 light years away has been seen waxing and waning like the moon. The discovery hints that hot gas giants come in two varieties.
The phases of Corot 1b were detected by a team at Leiden Observatory in the Netherlands, who analysed changes in the amount of red light from the system. A small component of the light smoothly dims and brightens as the planet orbits. This is probably alternation between the dark of Corot 1b's relatively cool night side and the glow of its red-hot day side, which permanently faces its star and reaches a temperature of about 2400 kelvin.

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Posts: 131433
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RE: CoRoT-Exo-1b
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Optical observations show night and day sides of tidally locked exoplanet Corot-Exo-1b.

For the first time, astronomers have mapped the phases of a planet outside our solar system - just as Italian astronomer Galileo Galilei drew the phases of Venus almost 400 years ago.
The extrasolar planet, or exoplanet, COROT-1b orbits a star about 1,600 light-years from Earth.
The planet is known as a "hot Jupiter," a class of exoplanets similar in size to Jupiter but orbiting very close to their host stars - usually less than an eighth of the distance between Mercury and the Sun.

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Title: Transiting exoplanets from the CoRoT space mission I - CoRoT-Exo-1b: a low-density short-period planet around a G0V star
Authors: P. Barge, A. Baglin, M. Auvergne, H. Rauer, A. Leger, J. Schneider, F. Pont, S. Aigrain, J.-M. Almenara, R. Alonso, M. Barbieri, P. Borde, F. Bouchy, H.-J. Deeg, R. De la Reza, M. Deleuil, R. Dvorak, A. Erikson, M. Fridlund, M. Gillon, P. Gondoin, T. Guillot, A. Hatzes, G. Hebrard, L. Jorda, P. Kabath, H. Lammer, A. Llebaria, B. Loeillet, P. Magain, T. Mazeh, C. Moutou, M. Ollivier, M. Patzold, D. Queloz, D. Rouan, A. Shporer, G. Wuchterl

Context. The pioneer space mission for photometric planet searches, CoRoT, steadily monitors about 12,000 stars in each of its fields of view; it is able to detect transit candidates early in the processing of the data and before the end of a run.
Aims. We report the detection of the first planet discovered by CoRoT and characterising it with the help of follow-up observations.
Methods. Raw data were filtered from outliers and residuals at the orbital period of the satellite. The orbital parameters and the radius of the planet were estimated by best fitting the phase folded light curve with 34 successive transits. Doppler measurements with the SOPHIE spectrograph permitted us to secure the detection and to estimate the planet mass.
Results. The accuracy of the data is very high with a dispersion in the 2.17 min binned phase-folded light curve that does not exceed 3.10-4 in flux unit. The planet orbits a mildly metal-poor G0V star of magnitude V=13.6 in 1.5 days. The estimated mass and radius of the star are 0.95±0.15Msun and 1.11±0.05Rsun. We find the planet has a radius of 1.49±0.08Rjup, a mass of 1.03±0.12Mjup, and a particularly low mean density of 0.38 ±0.05g cm^-3.

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