Ah, the downloaded file didn't have a .tar extension, and looking at the file wi...

SloopJon on Feb 15, 2017 | parent | context | favorite | on: Scientists make huge dataset of nearby stars avail...

Ah, the downloaded file didn't have a .tar extension, and looking at the file with the head utility made it seem like it was just a single TSV file. It is in fact a TAR file that expands into 1,699 .vels files.

Thanks for the explanation.