CoRoT Results

Did you notice how dense Corot-17b is?
I know there are transiting bodies with similar densities, but those have higher masses closer (or in) the brown dwarf realm, or else, much smaller radiuses and masses (super-earths).
The combination of Corot-17b's mass and radius would put it far from the other dots in such a graphic.
Is it a typo or not?
Becuse of this, I thought how massive a rocky planet could be. Probably much less massive than 2.45MJ. On the other hand, 20 years ago no one could imagine that there could be jovian planets close enough its parent star to have ridiculously short periods of 1 day and hotter than some stars in the dimmest end of the main sequence...

Corot-17b's density looks normal to me. A radius of 1.47 Rj is fairly typical for a hot Jupiter mass of 2.45 Mj. If anything it is somewhat under-dense.

Mongo: when it appeared on EPE the radius value was given as 0.5 R_J. Looks like this has been corrected.

Yes, I see they corrected the radius.
This is not the first time I see a typo in EPE.
BTW, did you know how massive a rocky planet, or metallic (or whatever non-jovian planet) could be? I remeber I saw somewhere ts is 60 MEarth, that is roughly two thirds the mass of Saturn. It seems too high, but...

From the Extrasolar Planets Encyclopaedia

15 Oct 2010: Three different groups, anylzing the same data than Queloz et al (2009) find a different mass for CoRoT-7b:
- Hatzes et al. (2010): 6.9 ± 1.4 MEarth
- Pont et al. (2010): 2.8 ± 1.4 MEarth
- Ferraz-Mello et al. (2010): 9 MEarth

Furthermore, on CoRoT-7 c
15 Oct 2010: By reanalyzing the same data than Queloz et al.(2009), Ferraz-Mello et al. (2010) find 13 MErath for the CoRoT-7 c mass.

The main problem with exact data on these planets is activity of the star

Ferraz-Mello et al. (2010) is now on arXiv.

Mass estimates:

8.5±1.5 Earth masses for CoRoT-7b
13.5±1.5 Earth masses for CoRoT-7c

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follow-up is completed in runs IRa01 (2 planets), LRc01 (3+1 planets), and SRc01 (0 planets)

I'm beginning to think that Corot in general discovery less than 100 transit planets.

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HARPS/La silla, SOPHIE/OHP, HIRES/Keck more than 35 nights per semester

Probably get about 10 nights on one new planet.

http://arxiv.org/abs/1101.0463

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Mass characterization of low-mass planets strongly depends on the star brightness and its rotational velocity. Table 1 indicates photon noise uncertainties on SOPHIE and HARPS in one hour exposure time for 3 different v sin i and different V-magnitudes. Transiting Super-Earths (K < 10m.s−1) can only be characterized around low-rotating stars brighter than mv=13, while transiting hot-Neptune (K < 30m.s−1) can be characterized with HARPS on stars up to mv=14. For stars fainter than mv=14, or fast-rotating stars, only giant planets and brown dwarves can be characterized.

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CoRoT so far has discovered 15 new transiting exoplanets and brown dwarves (Deleuil et al. this book). These discoveries are the fruit of CoRoT high-accuracy space-based photometry combined with an intensive ground-based photometric and spectroscopic follow-up of about 200 transiting exoplanet candidates for the first 3 years of CoRoT. Run report papers (IRa01: Moutou et al. 2009, LRc01: Cabrera et al 2009, SRc01: Erikson et al in prep., LRa01: Carone et al. in prep., LRc02: Bord´e et al. in prep.) present the observation and analysis sub-sampled of these candidates including:
- 50% of binary (SB1, SB2, BEB, blended EB);
- 10% of hot stars for which we cannot measure RV with enough precision to characterize the candidate’s mass (and could still be planetary);
- 10% of confirmed transiting exoplanets;
- 30% are the faintest stars or too low-priority candidates with poor planet likelihood which were not followed up or unsolved candidates due to photon noise limitation.

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To complete the characterization of the system, we observe Rossiter-McLaughlin RV anomaly (Winn et al., this book; Triaud et al., this book) during the transit. It permits us to measure the sky-projected angle between the spin of the star and the orbit of the planet. CoRoT-2b (Bouchy et al. 2008) and CoRoT-3b (Triaud et al. 2009) are spin-orbit aligned exoplanets while CoRoT-1b was revealed to be a misaligned planet (Pont et al. 2010). Observation of part of the transit of CoRoT-11b indicates another misaligned exoplanet (Gandolfi et al. 2010), although observations did not cover the complete transit. Part of the transits of CoRoT-9b and CoRoT-6b were observed by SOPHIE and HARPS and require more observations to conclude.

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More than 1000 spectra with signal-to-noise of up to 100 on about 200 transit candidates were taken with SOPHIE, HARPS, and HIRES during the first 3 years of CoRoT.

In general, it turns out, only the first 5 fields is 200 * 0.4 = 80 transit candidates that are difficult to confirm. But they may well be planets.

CoRoT-14b paper - massive, very hot Jupiter.

The extreme physical properties of the CoRoT-7b super-Earth

The search for rocky exoplanets plays an important role in our quest for extra-terrestrial life. Here, we discuss the extreme physical properties possible for the first characterized rocky super-Earth, CoRoT-7b (R_pl = 1.58 \pm 0.10 R_Earth, Mpl = 6.9 \pm 1.2 M_Earth). It is extremely close to its star (a = 0.0171 AU = 4.48 R_st), with its spin and orbital rotation likely synchronized. The comparison of its location in the (Mpl, Rpl) plane with the predictions of planetary models for different compositions points to an Earth-like composition, even if the error bars of the measured quantities and the partial degeneracy of the models prevent a definitive conclusion. The proximity to its star provides an additional constraint on the model. It implies a high extreme-UV flux and particle wind, and the corresponding efficient erosion of the planetary atmosphere especially for volatile species including water. Consequently, we make the working hypothesis that the planet is rocky with no volatiles in its atmosphere, and derive the physical properties that result. As a consequence, the atmosphere is made of rocky vapours with a very low pressure (P \leq 1.5 Pa), no cloud can be sustained, and no thermalisation of the planetary is expected. The dayside is very hot (2474 \leq 71 K at the sub-stellar point) while the nightside is very cold (50 to 75 K). The sub-stellar point is as hot as the tungsten filament of an incandescent bulb, resulting in the melting and distillation of silicate rocks and the formation of a lava ocean. These possible features of CoRoT-7b could be common to many small and hot planets, including the recently discovered Kepler-10b. They define a new class of objects that we propose to name "Lava-ocean planets".


Artist view of the CoRoT-7 system. Stellar wind and coronal mass ejections are schematized at the surface of the active star. A detailed view of CoRoT-7b, is represented, illustrating the main planetary features derived in the paper, including the temperature distribution, the presence of a featureless ocean of molten rocks and a structured continent of solid rocks. In our current understanding of planetary system formation and evolution, the presence of meteorites seems likely, and we represent impact craters on this continent. For the sake of visibility, the planetary size and planet-star distance are not to scale, nor is the relative luminosity of the planet and the star. The second planet of the system, CoRoT-7c, is visible in the distance.


Model internal structure of CoRoT-7b compared to Earth. Scaling of the different layers has been respected except for the magma ocean thickness, which has been increased in order to be visible.


Possible temperature (grey area) and density (dark curves) profiles used for computing the internal structure of CoRoT-7b. Several temperature profiles have been tested within the grey area without significant effects on the position of the layers and the size of the planet (ΔRpl /Rpl < 10-3). At this scale, density variations due to temperature contrasts are visible in the core (curve splits) but not in the mantle. In each layer, temperature profiles are assumed adiabatic, and fixed temperature jumps, similar to those encountered on Earth, are imposed at the boundaries. Within each layer, density variations are mostly due to the pressure increase (~ 630 GPa at the core-mantle interface, and ~ 1.7 TPa at the centre).

what about the high albedo of Kepler-10 b?

Wow... I mean, it was obvious that it was a pretty nasty place, but still having the surface of the planet glowing like a tungsten filament has got to be unpleasant.

Lazarus wrote:

Wow... I mean, it was obvious that it was a pretty nasty place, but still having the surface of the planet glowing like a tungsten filament has got to be unpleasant.

Unless you were planning to move out there...

Stalker wrote:

what about the high albedo of Kepler-10 b?

Seems thermal in nature. The light Kepler detected probably wasn't reflected light, but rather, light emitted from the glowing hot surface.

Which should be very considerable. The substellar point of CoRot-7b is described as reaching a temperature of ~2470K, while Kepler-10b reaches ~3040K, considerably hotter and presumably brighter in visible light. For comparison, the tungsten filament of an incandescent light bulb reaches ~2800K.

Mongo wrote:

Which should be very considerable. The substellar point of CoRot-7b is described as reaching a temperature of ~2470K, while Kepler-10b reaches ~3040K, considerably hotter and presumably brighter in visible light. For comparison, the tungsten filament of an incandescent light bulb reaches ~2800K.

It still amazes me when planet candidates have temperatures in the HR diagram registering as L and even M class star's temp.

One thing to note here is that the tungsten filament, which certainly appears quite "white" at close range, is at ~2800 K, which is cooler than "red" dwarfs such as GJ 581 and GJ 876...

Updated Corot-17 b page. Radius notably downsized (from 1.47 to 1.02 Jupiter radii). No coordinates yet but more parameters.

http://exoplanet.eu/star.php?st=CoRoT-17

There's a paper in the A&A forthcoming list for CoRoT-17b:

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Transiting exoplanets from the CoRoT space mission. XVII. The hot Jupiter CoRoT-17b: a very old planet
Sz. Csizmadia, C. Moutou, M. Deleuil, J. Cabrera, M. Fridlund, D. Gandolfi, S. Aigrain, R. Alonso, T. Guillot, et al.
Received: 03 April 2011 / Accepted: 27 April 2011
DOI: 10.1051/0004-6361/201117009

On the Mass of CoRoT-7b
http://arxiv.org/abs/1105.3372

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The mass of CoRoT-7b, the first transiting superearth exoplanet, is still a subject of debate. A wide range of masses have been reported in the literature ranging from as high as 8 M_Earth to as low as 2.3 M_Earth. Although most mass determinations give a density consistent with a rocky planet, the lower value permits a bulk composition that can be up to 50% water. We present an analysis of the CoRoT-7b radial velocity measurements that uses very few and simple assumptions in treating the activity signal. By only analyzing those radial velocity data for which multiple measurements were made in a given night we remove the activity related radial velocity contribution without any a priori model. We demonstrate that the contribution of activity to the final radial velocity curve is negligible and that the K-amplitude due to the planet is well constrained. This yields a mass of 7.42 +/- 1.21 M_Earth and a mean density of rho = 10.4 +/- 1.8 gm cm^-3. CoRoT-7b is similar in mass and radius to the second rocky planet to be discovered, Kepler-10b, and within the errors they have identical bulk densities - they are virtual twins. These bulk densities lie close to the density - radius relationship for terrestrial planets similar to what is seen for Mercury. CoRoT-7b and Kepler-10b may have an internal structure more like Mercury than the Earth.

http://nexsci.caltech.edu/conferences/Flagstaff/talks/Rouan.pdf

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Marseille 13-17 June 2011
4 new CoRoT planets will be announced !