| CoRoT Results | |
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+25Galzi ExplorerAtHeart Roland Borrey marasama tommi59 Mongo Bruno Stalker Sedna Daniel exofever TheoA Stardust lodp philw1776 AlexFR tesh90 Anarres Michael Johne exoplanet Borislav jyril Darkness nova Edasich Sirius_Alpha 29 posters |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: CoRoT Results 12th August 2014, 9:01 pm | |
| CoRoT-22 b: a validated 4.9 RE exoplanet in 10-day orbit http://arxiv.org/abs/1408.2576 - Quote :
- The CoRoT satellite has provided high-precision photometric light curves for more than 163,000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent transit surveys have shown that it is not always within reach of the radial-velocity detection limits. In this paper, we present a transiting exoplanet candidate discovered by CoRoT whose nature cannot be established from ground-based observations, and where extensive analyses are used to validate the planet scenario. They are based on observing constraints from radial-velocity spectroscopy, adaptive optics imaging and the CoRoT transit shape, as well as from priors on stellar populations, planet and multiple stellar systems frequency. We use the fully Bayesian approach developed in the PASTIS analysis software, and conclude that the planet scenario is at least 1400 times more probable than any other false positive scenario. The primary star is a metallic solar-like dwarf, with Ms = 1.099+-0.049 Msun and Rs = 1.136 (+0.038,-0.090) Rsun . The validated planet has a radius of Rp = 4.88 (+0.17,-0.39) RE and mass less than 49 ME. Its mean density is smaller than 2.56 g/cm^3 and orbital period is 9.7566+-0.0012 days. This object, called CoRoT-22 b, adds to a large number of validated Kepler planets. These planets do not have a proper measurement of the mass but allow statistical characterization of the exoplanet population.
_________________ Caps Lock: Cruise control for 'Cool'!
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Led_Zep SuperJovian
Number of posts : 721 Location : France Registration date : 2011-09-09
| Subject: Re: CoRoT Results 1st January 2015, 2:58 pm | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: CoRoT Results 7th April 2015, 8:28 pm | |
| _________________ Caps Lock: Cruise control for 'Cool'!
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Shellface Neptune-Mass
Number of posts : 283 Location : g2 17.∞ 997 t Registration date : 2013-02-14
| Subject: Re: CoRoT Results 8th April 2015, 10:10 am | |
| Well, maybe. - Quote :
- The model can measure the deformation and the orientation of the star, but not its rotation rate. The results of Section 4.2 show that for CoRoT-29, the quadrupole moment has a contribution 2 orders of magnitude larger than rotation. Actually, the quadrupole moment of CoRoT-29 measured from the gravity darkening is far too large, J2 = 0.028 ± 0.019, compared to the Sun, J⊙2 = (1.7 ± 0.4) · 10−7 (Lang 1999). Other authors have claimed large J2 values for fast-rotating stars, such as WASP-33 (J2 = 3.8 · 10−4, Iorio 2011), but not as large as for CoRoT-29.
The gravity darkening model, despite being the most satisfactory one considered, requires CoRoT-29 have an extremely peculiar nature compared to any normal K0 dwarf. I imagine it would be very difficult to explain the star's implied oblateness. Obviously, there is a lot more to be learned to properly understand this system. ( this is a relevant video) | |
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: CoRoT Results 8th April 2015, 2:41 pm | |
| Very strange. You don't often see Achernar being used as the closest point of reference for inferred properties of exoplanetary systems! | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: CoRoT Results 8th April 2015, 3:11 pm | |
| Could it be that the star is heavily spotted around the equator, or has polar phages? It may not be g-darkening at all. That would sound more like a K dwarf than the rapidly rotating Achernar-type star that the authors consider. _________________ Caps Lock: Cruise control for 'Cool'!
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Shellface Neptune-Mass
Number of posts : 283 Location : g2 17.∞ 997 t Registration date : 2013-02-14
| Subject: Re: CoRoT Results 8th April 2015, 6:21 pm | |
| There are multiple sections for different models considered as possible solutions to the irregular transit, y'know… - Quote :
- The spot fit yielded BIC = 133, whereas the gravity darkening fit produces BIC = 120. This BIC difference corresponds to a Bayes factor of around 665 for the gravity darkening model (i.e. if the prior probabilities for each model are the same, then the gravity darkening is 665 times more probable than the spot model). Moreover, to explain the observational evidence we are obliged to put requirements on the size and temporal evolution of the spot, which are completely ad hoc. We consider that there is enough evidence to discard the spotted star as a reasonable interpretation of the data.
Of all hypotheses considered, of which there are many, only stellar oblateness provides an (air quotes) "satisfactory" fit. I am not inclined to believe it is the correct model, however. It requires an exceptionally unlikely combination of stellar parameters, and then requires a Hot Jupiter to be in orbit and transiting, which is dicing with probability to an excessive degree. Nevertheless, the lack of a more satisfactory model means oblateness ought to be considered the most satisfactory model for the moment, but let's not be too surprised if that changes in future. Again, there is a lot more that is to be learned from this system in order to properly understand it. | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 25th August 2015, 4:15 am | |
| Another transiting brown dwarf: Corot-33 B. Transiting exoplanets from the CoRoT space mission XXVIII. CoRoT-33b, an object in the brown dwarf desert with 2:3 commensurability with its host star - Quote :
- We report the detection of a rare transiting brown dwarf with a mass of 59 M_Jup and radius of 1.1 R_Jup around the metal-rich, [Fe/H] = +0.44, G9V star CoRoT-33. The orbit is eccentric (e = 0.07) with a period of 5.82 d. The companion, CoRoT-33b, is thus a new member in the so-called brown dwarf desert. The orbital period is within 3% to a 3:2 resonance with the rotational period of the star. CoRoT-33b may be an important test case for tidal evolution studies. The true frequency of brown dwarfs close to their host stars (P < 10 d) is estimated to be approximately 0.2% which is about six times smaller than the frequency of hot Jupiters in the same period range. We suspect that the frequency of brown dwarfs declines faster with decreasing period than that of giant planets.
*Update* It has been listed at EPE as planet but I don't get the reason. http://exoplanet.eu/catalog/corot-33_b/
Last edited by Edasich on 25th August 2015, 8:35 am; edited 1 time in total (Reason for editing : EPE link) | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 24th September 2015, 1:51 pm | |
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 24th September 2015, 4:27 pm | |
| It's a good idea. _________________ | |
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tommi59 Jovian
Number of posts : 593 Age : 46 Location : Baile Atha Cliath Registration date : 2010-07-31
| Subject: Re: CoRoT Results 25th September 2015, 3:51 am | |
| No I do not think is good idea stalker in my opinion. We have and will have much more exoplanets so we do not need low mass stars as such brown dwarf to be exoplanet | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 25th September 2015, 4:23 am | |
| - Stalker wrote:
- It's a good idea.
Well in this case "exoplanet" count would increase notably, also acconting candidate BDs detected by timing around many cataclysmic variables, Algol and W UMa-type eclipsing binaries. | |
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 25th September 2015, 11:43 am | |
| There is already many "brown dwarf" (understand "burned deuterium in childhood") in EPE, because the limit planet/BD is at 20MJ, not 13MJ. You wont be able to tell the difference between a brown dwarf and a planet, because the deuterium burning take place during the contraction of the object and have almost no effect on its further évolution.
Personnally I separated EPE friendly planets, desert brown dwarfs and planetary mass companions in different counts, and many as nu Ophiuchi orbiting objets are obviously of planetary nature.
And I found only 77 true desert brown dwarf to date, thats not very much. _________________ | |
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 25th September 2015, 11:52 am | |
| Some papers to read, breaking the borders between planets and brown dwarfs. A Definition for Giant Planet Based on the Mass-Density RelationshipNuclear Fusion in the Deuterated cores of inflated hot JupitersI think the way of birth is now more important than mass. Some young planets have to be considered as low mass "stellar" object aka brown dwarfs, even if the mass is below deuterium burning limit (for example almost all youg wide separation compagnions discovered by imaging) In other hand, all substellar objets born in a protoplanetary disc must be called a planet, even if in the youth, the planet burned deuterium... And may be Jupiter and Saturn did it in the past according to some models! Of course it's my point of view, but I think we need to rethink our classification, just like what we did in 2006 in our solar system. _________________ | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 28th September 2015, 12:15 pm | |
| So should WASP-30 B and other transiting/non-transiting epistellar brown dwarfs (to say, MARVELS-1 b, MARVELS-4 Ab, MARVELS-5 b AND MARVELS-6 b) be listed then. | |
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 28th September 2015, 1:33 pm | |
| If CoRoT-15 b is listed, then yes. _________________ | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 5th October 2015, 9:48 am | |
| Another >30 Mj companion classed as planet at EPE: NLTT 41135 bShould we open a separate thread concerning massive substellar object treated ad "exoplanets"? In case I'd move this reply there. | |
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 5th October 2015, 2:52 pm | |
| I think we should talk more about Brown dwarf in general on tais forum. :-) _________________ | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: CoRoT Results 5th October 2015, 4:03 pm | |
| - Edasich wrote:
- Should we open a separate thread concerning massive substellar object treated ad "exoplanets"? In case I'd move this reply there.
I think that's a wonderful idea. _________________ Caps Lock: Cruise control for 'Cool'!
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Stalker Jovian
Number of posts : 540 Age : 33 Location : Paris, France Registration date : 2008-06-16
| Subject: Re: CoRoT Results 6th October 2015, 4:42 pm | |
| I propose "General brown dwarf news and discoveries" _________________ | |
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 31st October 2015, 5:17 am | |
| - Stalker wrote:
- I propose "General brown dwarf news and discoveries"
Another (imaged) brown dwarf added to planet list at EPE. Are we going to expand the "planet" concept? http://exoplanet.eu/catalog/beta_cir_b/ | |
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: CoRoT Results 2nd February 2016, 4:02 pm | |
| Remember CoRoT-29b with the asymmetric transit? Follow-up observations find no asymmetry. Palle et al. "The GTC exoplanet transit spectroscopy survey. IV.: No asymmetries in the transit of Corot-29b" http://arxiv.org/abs/1602.00506(arXiv preprint appears to suffer from some BibTeX errors, probably because the entire references section is missing) - Quote :
- While it is not impossible that both the CoRoT and the FTN data suffered from unfortunate instrumental effects causing a similar asymmetry, another explanation is that the poorly understood source of this asymmetry disappeared sometimes between 2012 and 2014.
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Daniel SuperEarth
Number of posts : 272 Registration date : 2009-11-14
| Subject: Re: CoRoT Results 20th July 2016, 1:24 pm | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: CoRoT Results 4th September 2017, 9:15 am | |
| A modified CoRoT detrend algorithm and the discovery of a new planetary companion https://arxiv.org/abs/1709.00351 - Quote :
- We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to detrend chromatic light curves. By means of robust statistics and better handling of short term variability, the implementation decreases the systematic light curve variations and improves the detection of exoplanets when compared with the original algorithm. All CoRoT chromatic light curves (a total of 65,655) were analysed with our algorithm. Dozens of new transit candidates and all previously known CoRoT exoplanets were rediscovered in those light curves using a box-fitting algorithm. For three of the new cases spectroscopic measurements of the candidates' host stars were retrieved from the ESO Science Archive Facility and used to calculate stellar parameters and, in the best cases, radial velocities. In addition to our improved detrend technique we announce the discovery of a planet that orbits a 0.79+0.08−0.09R⊙ star with a period of 6.71837±0.00001 days and has 0.57+0.06−0.05RJ and 0.15±0.10MJ. We also present the analysis of two cases in which parameters found suggest the existence of possible planetary companions.
_________________ Caps Lock: Cruise control for 'Cool'!
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Edasich dK star
Number of posts : 2267 Location : Tau Ceti g - Mid Latitudes Registration date : 2008-06-02
| Subject: Re: CoRoT Results 4th September 2017, 10:22 am | |
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