Corona-Australis DANCe. I. Revisiting the census of stars with Gaia-DR2
  data
  Corona-Australis is one of the nearest regions to the Sun with recent and
ongoing star formation, but the current picture of its stellar (and substellar)
content is not complete yet. We take advantage of the second data release of
the Gaia space mission to revisit the stellar census and search for additional
members of the young stellar association in Corona-Australis. We applied a
probabilistic method to infer membership probabilities based on a
multidimensional astrometric and photometric data set over a field of 128
deg$^{2}$ around the dark clouds of the region. We identify 313
high-probability candidate members to the Corona-Australis association, 262 of
which had never been reported as members before. Our sample of members covers
the magnitude range between $G\gtrsim5$ mag and $G\lesssim20$ mag, and it
reveals the existence of two kinematically and spatially distinct subgroups.
There is a distributed `off-cloud' population of stars located in the north of
the dark clouds that is twice as numerous as the historically known `on-cloud'
population that is concentrated around the densest cores. By comparing the
location of the stars in the HR-diagram with evolutionary models, we show that
these two populations are younger than 10 Myr. Based on their infrared excess
emission, we identify 28 Class II and 215 Class III stars among the sources
with available infrared photometry, and we conclude that the frequency of Class
II stars (i.e. `disc-bearing' stars) in the on-cloud region is twice as large
as compared to the off-cloud population. The distance derived for the
Corona-Australis region based on this updated census is $d=149.4^{+0.4}_{-0.4}$
pc, which exceeds previous estimates by about 20 pc.In this paper we provide
the most complete census of stars in Corona-Australis available to date that
can be confirmed with Gaia data.
