(Proposal ID) S16B-119

(PI) Kudo, Tomoyuki

(Proposal Title)
Search for planets exciting spiral structures

(Abstract)
The spiral structures is indicative of the dynamical processes in a proto-
planetary disk, which are possibly connected to the planet formation 
processes. In order to detect planets exciting spiral structures, we propose 
to observe 4 Herbig Ae star with spiral disks using SCExAO/HiCIAO. SCExAO will 
allow for high strehl ratios ~80% in the H-band. Combined with speckle nulling 
technique and PIAA coronagraph, the contrast level will be further improved by 
a factor of 5-10x. The 5 sigma detection limit will be achieved to 2 M_{J} at 
a separation of 70AU, assuming a distance of 140 pc. According to simulations 
coupled with radiative transfer calculations by Dong et al. 2016, if observed 
spirals are driven by a planet on a circular orbit outside the arms, then a 
~6M_{J} planet is needed at around 100 AU at a distance of 140 pc. Considering 
the SCExAO/HiCIAO capability, the planet candidates will be detected if it 
already exits. And, VAMPIRES can be also used as a visible aperture masking 
instrument to resolve the vicinity of central region. SCExAO/HiCIAO and 
VAMPIRES will be operated simultaneously in near IR and visible wavelengths. 
In this proposal we will focus on 1) a direct imaging of jovian planets 
exciting spiral structures and 2) a investigation for the roots of observed 
spirals driven by planet(s).