Lightroom cannot do this kind of work.
You will need to use Photoshop, or possibly some other image editor.
Thanks Per, however I found this reference from a photographer who isolated just meteors from multiple images and stacked them. "In Lightroom I blacked out everything but the meteors in the shots that contained them, saved those files, then used a star trails program to add them back into one shot of the surroundings and sky." Stacking in another program is easy if I can "black out" everything except a star.
Stacking in another program is easy if I can "black out" everything except a star.
In Develop, use the adjustment brush to select everything except the star. It will probably be easier if you start with a small brush to select all round the desired star, then switch to a much larger brush to select the rest of the image. Once you've selected the rest of the image, you could set the local exposure, highlights, and shadows all the way to the left to take the selection to black.
See this tutorial for how to use the brush: Lightroom CC – Enhancing Isolated Areas of an Image with the Adjustment Brush « Julieanne Kost's Blog