Quote:
Originally Posted by CraigS
Some interesting quotes from the paper ...
i) on the precision of the measurements:
"Long-term radial velocity monitoring at 1 m s−1 precision was necessary to detect the low RV amplitudes of these planets".
...
"Following 400 stars to search for radial velocity signals at the m s−1 level requires a lot of telescope time, and this survey is by construction a long-term project".
I'll bet it is ... oops .. not allowed to mention the 'b*t' word. Sorry.
ii) on atmosphere detection:
"The characterization of a significant sample of low-mass objects, through their mean density and some basic atmospheric properties, is also at hand and will bring much desired insights into their composition and the physical processes at play during planet formation".
Overall, it seems like they're trying to probe (establish?) the relationship between metallicity of the star and the planetary system mass. Pretty tenuous relationship at this stage, too - lots more data/discoveries required, I think. (Ie: from the graphs presented in the conclusion section).
Cheers
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There's been dozens of surveys done over a period of 15-20 years or more. They use the data from all of them. However, there's not been a single multi-decade continuous survey undertaken yet. That's why they should build a few large scopes dedicated to such a project.
There is a relationship between metallicity and the planets that form around these stars. The higher the star's metallicity, it seems, the more likely the planets forming around it will be giant planets and the higher the Fe/H ratio, the heavier the planets are. Conversely, the less metallicity, the smaller the planets or even no planets at all. The metallicity determines the size and the make up of the protoplanetary disks around the stars. High metallicity means more material, especially refractory elements...low metallicity means less material and mostly gases and ices.