CoRoT Results

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Re: CoRoT Results

Post by AlexFR on 10th May 2009, 6:57 am

Hello,


This data about CoRoT-7 are not published yet! Please, can you remove the link, the plot and the table from this web site until the publication of DQ's article.


Thanks

Alexandre

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Re: CoRoT Results

Post by Borislav on 10th May 2009, 9:34 am

I delete link, the plot and the table. Sorry.

When wait the article about Corot-7?

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Re: CoRoT Results

Post by AlexFR on 10th May 2009, 10:29 am

Thank you for this.

This article about the multiple system CoRoT-7 will be summited very soon... but it isn't a simple system and before the public announcement they are the referrer opinion.

Don't worry, you will hurt the public communique.

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Re: CoRoT Results

Post by Sirius_Alpha on 26th May 2009, 8:19 am

CoRoT-2a magnetic activity: hints for possible star-planet interaction
http://arxiv.org/abs/0905.3633

Abstract wrote:CoRoT-2a is a young (about 0.5 Gyr) G7V star accompanied by a transiting hot-Jupiter, discovered by the CoRoT satellite (Alonso et al. 2008; Bouchy et al. 2008). An analysis of its photospheric activity, based on spot modelling techniques previously developed by our group for the analysis of the Sun as a star, shows that the active regions on CoRoT-2a arised within two active longitudes separated by about 180 degrees and rotating with periods of 4.5221 and 4.5543 days, respectively, at epoch of CoRoT observations (112 continous days centered at 2007.6). We show that the total spotted area oscillates with a period of about about 8.9 days, a value close to 10 times the synodic period of the planet with respect to the active longitude pattern rotating in 4.5221 days. Moreover, the variance of the stellar flux is modulated in phase with the planet orbital period. This suggests a possible star-planet magnetic interaction, a phenomenon already seen in other extrasolar planetary systems hosting hot-Jupiters.

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Re: CoRoT Results

Post by Lazarus on 28th May 2009, 2:36 pm

Dudes here's an idea -- next time there's a major announcement let's not have Extrasolar Visions II be one of the sites that breaks the embargo (like seems to have happened every other time). Or do we have no respect for the scientists who bring us the information we're so interested in???
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Re: CoRoT Results

Post by Sirius_Alpha on 29th May 2009, 8:11 am

Though I'm not sure, I think a lot of the time, some confusion comes from not knowing what information is supposed to be public or not.

Perhaps only published papers and official announcements should be reported here?

Does the schedule of the Spitzer observations break any embargos? (i.e. the knowledge that Spitzer was aimed at GJ 876 with the hopes of detected d?)

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Re: CoRoT Results

Post by Sirius_Alpha on 7th June 2009, 12:51 pm

Information regarding CoRoT-7 has been made public.

Extrasolar Planets Encyclopaedia Bibliography

FRIDLUND M. , 2009 (update : 04 June 2009)
CoRoT Update
in Missions for Exoplanets: 2010-2020, Pasadena, April 2009

paper
http://exep.jpl.nasa.gov/presentations/48-03-2-Fridland.pdf

Turns out there are three planets at CoRoT-7

Updated CoRoT Results table.

StarPlanetMassP (d)Radiusa (AU)
CoRoT-1b1.03 J1.5089557 d1.49 J0.0254
c?
CoRoT-2b3.31 J1.7429964 d1.465 J0.0281
CoRoT-3b21.66 J4.2568 d1.008 J0.052
CoRoT-4b0.72 J9.20205 d1.19 J0.09
CoRoT-5b0.999 J4.0378962 d1.32 J0.049
CoRoT-6b3.3 J8.89 d1.15 J
CoRoT-7b0.0186 J0.853530.1720.017
c0.0390 J3.691 0.0450
d0.0525 J9.031 0.08

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Re: CoRoT Results

Post by Sirius_Alpha on 16th June 2009, 8:08 pm

Secondary Eclipse detected for CoRoT-2b.

The secondary eclipse of the transiting exoplanet CoRoT-2b
http://arxiv.org/abs/0906.2814
Abstract wrote:We present a study of the light curve of the transiting exoplanet CoRoT-2b, aimed at detecting the secondary eclipse and measuring its depth. The data were obtained with the CoRoT satellite during its first run of more than 140 days. After filtering the low frequencies with a pre-whitening technique, we detect a 0.0060$\pm$0.0020% secondary eclipse centered on the orbital phase 0.494$\pm$0.006. Assuming a black-body emission of the planet, we estimate a surface brightness temperature of T$_{\rm p,CoRoT}$=1910$^{+90}_{-100}$ K. We provide the planet's equilibrium temperature and re-distribution factors as a function of the unknown amount of reflected light. The upper limit for the geometric albedo is 0.12. The detected secondary is the shallowest ever found.

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Re: CoRoT Results

Post by Sirius_Alpha on 12th July 2009, 8:28 pm

Secondary Eclipse detected for CoRoT-1b

The secondary eclipse of CoRoT-1b
http://arxiv.org/abs/0907.1653

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 centered 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.

Additionally, updated parameters for CoRoT-5 b
http://exoplanet.eu/planet.php?p1=CoRoT-5&p2=b

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Re: CoRoT Results

Post by Lazarus on 16th July 2009, 5:04 pm

Planet formation by nucleated-instability: comparison with the two first CoRoT runs

Forthcoming paper (available if you register for free new articles access at A&A) compares the COROT results to theoretical predictions of planet formation.

Conclusion: COROT is not detecting as many planets as predicted, though if the distributions are limited to V<14 then there is a better match. Various possibilities, e.g. RV bottleneck for faint stars, noise effects for such stars.
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Re: CoRoT Results

Post by Edasich on 19th July 2009, 9:42 am

Moreover I've not got why they take so much to reveal host stars' parameters. Between 7 (nearly) confirmed planetary candidates, only 3-4 stars are kwown where they are and the features of theirs (I mean mass, distance, coordinates, Teff, radii...) Question Rolling Eyes
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Re: CoRoT Results

Post by Sirius_Alpha on 19th July 2009, 10:46 am

Maybe they lost the stars Laughing.

More likely, they may not want anyone coming up and discovering anything while they're still working with the system, though I don't know why they would be.

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Re: CoRoT Results

Post by Edasich on 19th July 2009, 12:13 pm

Lol, yes Laughing

Moreover with such skimpy results.

They have written dozens of articles about Corot-2 and its planet whereas much more interesing (and decisive) infos have come from HD 189733 b.

Sure they have the transiting Corot-7, the smallest planet detected so far, but so few informations at all.

Another point, maybe offtopic: have you noticed the California Carnegie Homepage (i.e exoplanets.org) not updated since long time? It keeps displaying 228 exoplanets (we'd have reached 353!!).

Nevertheless they have opened an exoplanet2009.org page only to say Corot-exo-7 being detected. Enough. Nothing more...

A bit weird, ain't it? Rolling Eyes
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Re: CoRoT Results

Post by Sirius_Alpha on 19th July 2009, 7:13 pm

HD 189733 b has an advantage over the CoRoT targets in that it is bright, leading to a far higher Signal/Noise ratio in the photometic, and radial velocity data. The CoRoT stars, being dim, take a lot more observing time.

I've already given up on exoplanets.org, but didn't know there was an exoplanet2009.org. Perhaps since the paper describing the discovery of CoRoT-7 has not yet appeared, they're not saying much on the topic.

Edit:
The Rossiter-McLaughlin effect for CoRoT-3b has been measured.

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Re: CoRoT Results

Post by Sirius_Alpha on 19th July 2009, 8:23 pm

Composition and fate of short-period super-Earths: The case of CoRoT-7b
http://arxiv.org/abs/0907.3067

Context. The discovery of CoRotT-7b, a planet of radius 1.68 +/- 0.09 R_Earth, with an orbital period of 0.854 days demonstrates that small planets can orbit extremely close to their star.
Aims. Several questions arise concerning this planet, in particular concerning its possible composition, mass and fate. Methods. We use knowledge of hot Jupiters, mass loss estimates and models for the interior structure and evolution of planets to understand its composition, structure and evolution.
Results. Although detailed modeling should address this problem, we show that a relatively significant mass loss ~10^11 g/s is to be expected, independently of the planet's composition. Given the closeness to the star, we find that the planet size is compatible with the observations only if the planet contains less than 1% of its mass in hydrogen and helium and less than 20% in steam. Due to the significant evaporation rate, it is most likely that the planet is made only of iron and silicates, which implies that its mass should be in the range 5 to 15 M_Earth. However, the origin of CoRoT-7b is unknown: It may have always had a terrestrial composition, it may be the remnant of a Uranus-like ice giant, or a gas giant with a small core that would have been entirely stripped of its gaseous envelope.
Conclusions. Our predictions can be tested by measurements of the planet mass and possibly by the detection of evaporating silicates, with a rate that should be within an order of magnitude that measured for HD209458b

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Re: CoRoT Results

Post by Edasich on 21st July 2009, 5:11 am

The exoplanets.org page has been updated and signs 358 planets but try browse the Catalog of Nearby Exoplanets and it does not display the page. Sad
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Re: CoRoT Results

Post by Sirius_Alpha on 21st July 2009, 9:44 am

The five exoplanets that are are apparently missing from the Extrasolar Planet Encyclopaedia are probably WASP-16 through WASP-20. At least that's a guess.

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Re: CoRoT Results

Post by Edasich on 21st July 2009, 10:13 am

Plus HD 177830 c and HD 68988 c, additional planet nof confirmed or missing at EPE.

However it's better quit the discussion because it's quite offtopic.

This one is about Corot results Cool
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Re: CoRoT Results

Post by philw1776 on 25th July 2009, 1:38 pm

COROT has been operational over 2 years. Given an assumed 1 year embargo on detections for investigator publications, aren't there still fewer than expected detections so far? Maybe the verification process, using access to large terrestrial telescopes to eliminate spurious error sources limits the flow of announcements.
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Re: CoRoT Results

Post by Sirius_Alpha on 25th July 2009, 5:02 pm

You're right on both counts. CoRoT has indeed not found as many planets as was expected, even considering the difficulty in follow-up observations.

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Re: CoRoT Results

Post by Edasich on 30th July 2009, 5:34 am

According to this paper, CoRoT would have detected so far 50 transiting planet candidates.

Planetary transit candidates in COROT-IRa01 field

Context: CoRoT is a pioneering space mission devoted to the analysis of stellar variability and the photometric detection of extrasolar planets.Aims: We present the list of planetary transit candidates detected in the first field observed by CoRoT, IRa01, the initial run toward the Galactic anticenter, which lasted for 60 days.Methods: We analysed 3898 sources in the coloured bands and 5974 in the monochromatic band. Instrumental noise and stellar variability were taken into account using detrending tools before applying various transit search algorithms.Results: Fifty sources were classified as planetary transit candidates and the most reliable 40 detections were declared targets for follow-up ground-based observations. Two of these targets have so far been confirmed as planets, COROT-1b and COROT-4b, for which a complete characterization and specific studies were performed

A list with 50 stars is available. With exoplanet candidate densities too (I think, I have look a "rho").
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Re: CoRoT Results

Post by Sirius_Alpha on 30th July 2009, 9:02 am

O_O
Look at those transit depths! Lots of them are < 1%!
Knowing both the period and duration of transit should allow an estimate of the semi-major axis (in stellar radii).

Knowing this, the V mag of the host star, and the transit depth, is there anything else we can coax out of these numbers?

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Re: CoRoT Results

Post by philw1776 on 30th July 2009, 11:41 am

Bottom line from reading the paper it looks as if the confirmation process, most likely from ground based sources, is one bottleneck to formally announcing new planets. From the report it seems as if there are several tens of candidates awaiting confirmation, or lack of same. Of course longer period planets require lots more time to observe multiple transits.
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Re: CoRoT Results

Post by Edasich on 30th July 2009, 12:15 pm

Assuming all of those star located at 1500 light years from Sun alike CoRoT-1 (and its distance estimate is still blurry at the moment...), I get several late-type stars with relatively low luminosities (L=0.16 LSun) and some Solar analogues.

But it's quite speculative Razz
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Re: CoRoT Results

Post by Edasich on 31st July 2009, 7:51 am

Corot-7 host star revealed:

http://exoplanet.eu/star.php?st=CoRoT-7

http://simweb.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=GSC+4799-1733&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id
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Re: CoRoT Results

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