A coronagraphic search for brown dwarfs and
planets around nearby stars
Nakajima, T.; Morino, J. I.; Tsuji, T.;
Suto, H.; Ishii, M.; Tamura, M.; Fukugawa, M.; Murakawa, K.; Miyama,
S.; Takami, H.; Takato, N.; Oya, S.; Hayashi, S.; Kudo, T.; Itoh, Y.;
Oasa, Y.; Oppenheimer, B. R.
Astronomische Nachrichten, 326, 952-957 (2005).
Abstract
We have started a corongraphic search for brown dwarfs and planets
around young nearby stars within 20 pc of the Sun, using the adaptive
optics coronagraph, CIAO, on Subaru. The dynamic range we have achieved
is Δ = 13 at 2.5"
from the central star. For a typical target with K = 7 at 10 pc, the
limiting absolute magnitude is MK = 20. We apply two
kinematical age criteria to select M and K dwarfs statistically younger
than 350Myr. The first criterion is a small velocity deviation from the
velocity of LSR. The second is a (U, V,W ) velocity vector similar to a
particular young moving group. The combination of the age and magnitude
limits implies that the mass limit for giant planet detection is about
2 MJ. We show a sample image of a target field at 3 pc of
the Sun with faint companion candidates, to be followed up for the
common proper motion test. We give a brief description of our
procedures for data acquisition, reduction, and analysis
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