Hot Jupiters are not only the dark?

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Hot Jupiters are not only the dark?

Post by Borislav on 21st April 2010, 12:45 pm

For many years it was thought that hot Jupiters are very dark (compared with Jupiter Ag=0.5).

http://arxiv.org/abs/astro-ph/9907195
http://arxiv.org/abs/astro-ph/0308413
http://arxiv.org/abs/1002.1638
Tau Bootis Ag<0.3 <55 ppm

http://arxiv.org/abs/astro-ph/0310489
http://adsabs.harvard.edu/abs/2008ASPC..398..397R
HD75289b Ag<0.12 <66 ppm

http://arxiv.org/abs/0711.4111
HD209458 <7(9)ppm or Ag<0.038(0.045) 1sigma Ag<0.08 3sigma Ag<0.13

Then followed by the first detection of the secondary eclipse

http://arxiv.org/abs/0904.1208
http://arxiv.org/abs/0907.1653
Corot-1b 160(60) ppm Ag=0.10-0.20

http://arxiv.org/abs/0906.2814
Corot-2b 60(20) ppm Ag=0.06(0.06)

http://arxiv.org/abs/1001.0413
HAT-P-7b 63 ppm Ag=0.18

and finally presents the planet today, which are geometric albedo is close to Jupiter

http://arxiv.org/abs/1004.3538
Kepler-7b 47(14) ppm Ag=0.38(0.12)

in addition
Kepler-5b 24(14) ppm Ag=0.18(0.09)

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Re: Hot Jupiters are not only the dark?

Post by Sirius_Alpha on 21st April 2010, 12:49 pm

This paper suggests that the hot Jupiters may not be as dark as assumed.

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Re: Hot Jupiters are not only the dark?

Post by marasama on 21st April 2010, 12:57 pm

I wonder if the closer they get, the whiter they are? Vaporized silicates and metals reflecting a lot of light. Making it look white due to the multitude of colors being relfected.

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Re: Hot Jupiters are not only the dark?

Post by Borislav on 21st April 2010, 1:09 pm

Sirius_Alpha wrote:This paper suggests that the hot Jupiters may not be as dark as assumed.

Thank you. Why then had I not seen this work? But I see that most of the measured secondary eclipses in the near infrared using Spitzer or ground-based telescopes with adaptive optics. This is not quite familiar geometric albedo, because the hot Jupiters in this range themselves radiate much heat. In the optical range while the secondary eclipse measured only for the 5 planets.

http://arxiv.org/pdf/1001.0012v1
HAT-P-7b8 3017 0.65 1.30(11) 10−4 3033(35) 1.22(16) 10−4 0.55(4) 0.0(1) 8.3

after the conference in August 2009, they revised the value of the depth of the secondary eclipse in the light of elliptical vibration stars under the action of tidal forces from the planet.

http://arxiv.org/abs/1001.0413
As seen in Fig. 3, the depth of the occultation is 85.8 ppm, and the night-side
contribution of the planet is 22.1 ppm, giving a day-side peak flux enhancement of
63.7 ppm. Using the peak planet to star flux of 63.7 ppm yields Ag=0.18.

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Re: Hot Jupiters are not only the dark?

Post by Lazarus on 21st April 2010, 2:44 pm

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Re: Hot Jupiters are not only the dark?

Post by Borislav on 21st April 2010, 3:18 pm


Sorry, I not see.

Another interesting point
]http://arxiv.org/pdf/1004.3538v1

4.1.2.
Secondary eclipse Kepler-4b
We here consider the eccentric model only since this has now been accepted over the circular model. Eccentric fits do not find any significant detection of the secondary eclipse. Secondary depths 69.1 ppm are excluded to 3-sigma confidence, which corresponds to geometric albedos greater than unity and thus this places no constraints on the detectability of reflected light from the planet. The thermal emission is limited by this constraint such that TP,brightness 3735K, which places no constraints on redistribution.


In this file photometry for Kepler-4b for the first month
http://archive.stsci.edu/pub/hlsp/kepler_hlsp/KPLR11853905/hlsp_exo_kepler_phot_KPLR11853905_kep_v1.0_dtr.txt

To cite this photometry to the phase for a certain period of the planet, to take the averages of 40 points and remove the value of the primary eclipse, we get a curve


Circled this is the first detection of the secondary eclipse in the optical range for hot Neptune?

If we take it deep for 20 ppm, then the geometric albedo of the leaves in the area 1.6. So it really wrong?

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Re: Hot Jupiters are not only the dark?

Post by Sirius_Alpha on 21st April 2010, 4:02 pm

Well the problem is that the depth you circled isn't significant, as the authors of that paper write. Note there's also two other dips in brightness at ~0.1 and ~0.8.

You can't make a convincing case for what you have circled being the secondary eclipse of the planet because you can't rule out noise as the source.

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Re: Hot Jupiters are not only the dark?

Post by Borislav on 21st April 2010, 4:15 pm

If you use an algorithm "Box-fitting Least Squares"



The maximum peak corresponds to the period 3.21 days, the system adjacent peaks - multiple times to him. If you now remove from the data points that fall on the transit and repeat the procedure, then the background noise, we again see the highs:



The provisions of the maxima again multiples of the period of the planet, which indicates their nature - is a secondary transit.

Recent calculations about the algorithm did not me. But I was very interested, they are true or not?

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Re: Hot Jupiters are not only the dark?

Post by Sirius_Alpha on 21st April 2010, 4:25 pm

That's really interesting. I think you might be on to something.
Are you sure that the signal is not an artifact of removing the points during the planet transit? (do they have a ~0.5 phase offset?)

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Re: Hot Jupiters are not only the dark?

Post by Borislav on 21st April 2010, 4:35 pm

Calculations were carried out not me, and another man several weeks ago. So do not ask anyone. But with the release of fresh articles from the group of Kepler, I was reminded of this. It is possible to use oklo.org processing photometry Kepler?

Also he said that a similar procedure could not find traces of the secondary eclipses in the photometry of the other planets Kepler (from 5 to 8 ). I explained it more faint stars or more active stars. As we now know for the two planets secondary eclipse yet been found.

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Re: Hot Jupiters are not only the dark?

Post by Sirius_Alpha on 21st April 2010, 4:44 pm

You can probably use Systemic to fold the data over itself and try to actually see that secondary transit, but the software is pretty much fully dedicated to radial velocity fits. Its usefulness here would be limited.

Also he said that a similar procedure could not find traces of the secondary eclipses in the photometry of the other planets Kepler (from 5 to 8 )
This isn't very promising for the detection of secondary transits of Kepler-4 b, considering their 3.5-sigma detection of Kepler-7 b's secondary eclipse, and the weak, 2.3-sigma detection of Kepler-5 b's secondary eclipse.

I think it fair to say that if he could not demonstrate the detection of Kepler-7 b's secondary eclipse, claims to detect the (presumably much lower amplitude) secondary eclipse of Kepler-4 b will not survive under scrutiny.

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