(CN), and ethynide (C2H). Protoplanetary
disks also contain carbonaceous and silicate
dust grains, which coagulate over time, grow
in size, and settle towards the disk midplane.
Present theories hold that giant planet formation in disks likely occurs via one of two
mechanisms: core accretion or gravitational
instability. In the core accretion scenario,
ice-covered dust particles collide and stick
together, growing into ever-larger rocky
bodies; planetesimals form from this buildup
of rocky material, and their collisions eventually build super-Earth-mass planetary “cores.”
Such massive cores can then rapidly collect
gas from the disk to form giant planets.
In contrast, the gravitational instability theory holds that planets form when a perturbation in the disk causes a large amount of disk
material to collapse and form a planet essentially all at once. Hence, this rapid process is
similar to that by which a young central star
forms from its birth cloud.
Under either scenario, once a massive planet
forms, co-orbiting material either accretes
onto the planet or is accelerated radially
in the disk via spiral density waves, which
cause material approaching them to speed
up — until they reach the perturbed regions,
where they slow down and linger. These
mechanisms result in ring-like or spiral structures in the disk characterized by sharp radial gradients in both surface density and
particle size.
Our team is interested in studying planet
formation around young nearby stars within
~ 30 AU, where we can search for evidence
for gas giant planet formation on scales
similar to that of our Solar System. We do so
by focusing on a handful of solar mass stars
within ~ 300 light years (ly) of Earth that are
surrounded by, and actively accreting material from, gas-rich circumstellar disks.
Target: V4046 Sagittarii
Our team has been closely scrutinizing one
such star-disk system: V4046 Sagittarii (Sgr). )1她