discovering debris disks around young stars
and characterizing the structure present in
spatially resolved scattered-light images. In
a study recently accepted for publication in
The Astronomical Journal, the GPIES team
presents the first resolved images of debris
disks around four members of the Scorpius-
Centaurus (Sco-Cen) association.
Sco-Cen is the nearest OB association to the
Sun, with member distances ranging from
about 110 to 140 parsecs and ages of 10-16
million years. It is a particularly useful labo-
ratory for studying debris disks, as the infra-
red excess observed in young massive stars
tends to be greatest around this age. Three
of the disks newly imaged with GPI appear
symmetric in morphology and brightness
distributions, but vary in inclination and ra-
dial extent.
The disk around the fourth star, HD 98363,
shows significant asymmetry that could in-
dicate the presence of a sizable planet. How-
ever, HD 98363 also has a wide co-moving
stellar companion, separated by 7,000 AU,
that has its own debris disk at a different
inclination and with differing morphologi-
cal peculiarities. This makes HD 98363 A/B
the first binary system with two spatially re-
solved debris disks; the disks are misaligned
by about 60 degrees. Depending on the or-
bital eccentricity, it is possible that the mor-
phological irregularities seen in both debris
disks could result from external dynamical
perturbations of the other star in the system.
The large separation prevents an estimation
of either the inclination or eccentricity of the
binary orbit.
The new results contribute to the census of
disks and the panoply of disk structures ob-
served around hot young stars at this criti-
cal stage in the development of planetary
systems. A total of 15 stars in the Sco-Cen
association now have debris disks that have
been resolved in scattered light, and at least
seven of these show evidence for asymme-
try. Figure 3 displays a gallery of images of
Figure 3.
Map of the Scorpius-
Centaurus association
in Galactic coordinates
with stars having
resolved scattered-light
disks and imaged giant
planets indicated. Proper
motions are represented
by the vectors. Green
points represent previ-
ously resolved debris
disks, while gold points
are the four new sys-
tems. Red points indicate
stars with imaged giant
planets; HD 106906 has
both a resolved debris
disk and an imaged
planet. The majority of
the images are from GPI.
Credit: Hom et al., The
Astronomical Journal,
in press
January 2020
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