Spectrum of young extrasolar planet yields surprising results

[renormalised (Carl)]

http://www.physorg.com/news202575672.html

The spectrum of one of the planets orbiting HR8799, which is about 130 light years away, shows that not all giant planets behave as they're supposed to. Turns out there is a class of giants which maybe dustier than usual and appear hotter as a consequence. Based on the conventional models for giant planet formation, this particular planet should be about 400K cooler than the 1200K they measured. However, when the models were corrected for a much dustier, cloudy atmosphere, the models agreed far better with the data.

Hopefully, they'll be able to get better data as time goes by and also begin to get spectral data from more examples of planets orbiting other stars.

[CraigS]

I notice they're using 'Direct spectroscopy' to do the measurements.

There was another thread in the Solar System Forum the other day where Titan occulted a double binary star system.
The notorious "mike Brown" of Caltech, ('the man who killed Pluto'), was involved in the analysis. In his paper, they used the 'light curve dipping', (meaning intensity, rather than spectroscopy), as a way to measure the temperature of Titan's atmosphere:

"The gradual drop of a star’s lightcurve at the point of immersion into the body’s atmosphere, and the subsequent rise at emersion, can be inverted to derive the local temperature and density profiles in the microbar pressure range. The primary cause of the dimming is differential refraction, effectively defocusing light rays in the plane of the local density gradient along the ray’s trajectory."

I wonder if they can do this for one that's 130 lyrs away ?

(Perhaps the spectrum method is already embedded in the lightcurve calculations ? They didn't go into that detail in the Titan occultation paper).

Cheers

[renormalised (Carl)]

Not likely, you'd need something as powerful as the OWL to get a large enough image so you could watch the planet occult a background star.

Might have to wait awhile till the OWL gets built, if it ever does!!!.

The light curve dipping method and spectroscopy are not the same. There's no embedding of the spectrum in the light curve calculations.