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The PASTEL catalogue

The PASTEL catalogue (Soubiran et al. 2010, Soubiran et al. 2016) lists stellar atmospheric parameters calculated from spectroscopic measurements, in particular the effective temperature Teff, surface gravity log(g), and metallicity [Fe/H]. Lower surface gravities correspond to giants (they're much larger for a given mass, so the surface is much further away from the centre of gravity), and higher values to dwarfs. A metallicity of zero corresponds to a star with the same iron abundance as the sun.

I don't have a ready reference to explain the plot – I'm learning by asking friends who did astro for variables to try out, and then looking at the results. Looking at [Fe/H] versus log(g), there's a noticeable fall in the density of points at around log(g) = 3.5, separating the giants from everything else (the 2016 paper linked above puts it at 3.2 rather than 3.5). There's also a population of metal-poor giants, and a few very hot dwarf stars(?). Most of the stars fall close to a straight line in the log-log plot of surface gravity against effective temperature.

Mouse controls: Left-click and drag to rotate; alt (Mac)- or ctrl (Windows)-click-drag or middle-click-drag to pan; scroll or shift-click-drag to zoom. Touch screen controls: one finger to rotate; two-finger scroll to pan; pinch to zoom. (If the points don't appear, try giving it a quick rotate and hopefully it'll fix itself.)

You can see how the plot is constructed in the HTML source.

The PASTEL catalogue can be downloaded from here. It's in fixed-width format, and the R script I used to turn the relevant fields into JavaScript (after deleting the non-data rows) is here, which sources my main JS-writing function write_three_d.R.

Posted 2016-10-03.

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