A wide survey for circumstellar disks in the Lupus complex
  Previous star formation studies have, out of necessity, often defined a
population of young stars confined to the proximity of a molecular cloud. Gaia
allows us to examine a wider, three-dimensional structure of nearby star
forming regions, leading to a new understanding of their history. We present a
wide-area survey covering 494 square degrees of the Lupus complex, a
prototypical low-mass star forming region. Our survey includes all known
molecular clouds in this region as well as parts of the Upper Scorpius (US) and
Upper Centaurus Lupus (UCL) groups of the Sco-Cen complex. We combine Gaia DR2
proper motions and parallaxes as well as ALLWISE mid-infrared photometry to
select young stellar objects (YSOs) with disks. The YSO ages are inferred from
Gaia color-magnitude diagrams, and their evolutionary stages from the slope of
the spectral energy distributions. We find 98 new disk-bearing sources. Our new
sample includes objects with ages ranging from 1 to 15 Myr and masses ranging
from 0.05 to 0.5 solar masses , and consists of 56 sources with thick disks and
42 sources with anemic disks. While the youngest members are concentrated in
the clouds and at distances of 160 pc, there is a distributed population of
slightly older stars that overlap in proper motion, spatial distribution,
distance, and age with the Lupus and UCL groups. The spatial and kinematic
properties of the new disk-bearing YSOs indicate that Lupus and UCL are not
distinct groups. Our new sample comprises some of the nearest disks to Earth at
these ages, and thus provides an important target for follow-up studies of
disks and accretion in very low mass stars, for example with ALMA and ESO-VLT
X-Shooter.
