Enhancement: Gaia queries for stellar properties

[bmorris3]

Enhancement proposal: use astroquery to get the stellar distance and radius like I do in this example, rather than hard-coding the answers into the notebook. You'll need to come up with a more clever way of selecting the correct answer from the query response than choosing the first row, as I did in the example. You might find that the answer is the star closest to the input coordinates. You can measure distances between coordinates using SkyCoord.separation(). 📐

[tcjansen]

Just as an update on this, the astroquery.Gaia table has a column for distance to the input coordinate, so I used that in place of SkyCoord.separation().

As for choosing the star nearest to the given coordinates (which is what I would have suggested as well), it worked great for HAT-P-11, but became a problem when SkyCoord and Gaia disagreed on the RA and Dec of Trappist-1... they give:

SkyCoord: 346.622, -5.0414
Gaia: 346.626, -5.0435

Since Gaia has a source closer to the SkyCoord coordinates than its TRAPPIST-1 coordinates, it selects the wrong object.

What's more, Gaia unfortunately doesn't have a stellar radius for TRAPPIST-1...
All to say I think we need to query a different catalog for this star!

[bmorris3]

Ok, let's supply it with the radius, distance, and effective temperature parameters for TRAPPIST-1 manually from Gillon et al. 2017.