Figure 2.
The non-detection of
planetary candidates is
interesting because it
was unexpected. Using
the occurrence rate of gi-
ant planets on wide orbits
that was inferred by pre-
vious surveys — which
assume that the mass
function at wide separa-
tion rises for lower mass-
es as it does for closer-in
planets found by radial
velocity — we expected
to discover between five
to eight new planets. The
survey’s null result is not
due to a lack of sensitiv-
ity, as the expected depth
was reached.
Example of a planetary
candidate (circled)
around a young star.
Clockwise starting from
upper left, we see an
image at 0.9 µm (CFHT,
MegaCam), at 1.2 µm
(Gemini-S, F2), at 3.6 µm
(Spitzer), and at 4.5 µm
(Spitzer). This candidate
turned out to be a
background object.
Credit: Frédérique Baron.
Figure 3.
Average completeness
map for the WEIRD
survey. Our results
are shown in shades
of magenta and the
contours correspond
to the probability of
detecting a planet of a
given mass and semi-
major axis. The various
boxes correspond to the
range in masses and
semi-major axes where
the surveys from other
teams were sensitive.
All of the dotted boxes
used high contrast
imaging, while the
solid boxes used deep
seeing-limited imaging.
Our observations probe
larger semi-major axes
than high contrast
imaging surveys, but are
insensitive to semi-major
axes where high contrast
observations are mostly
sensitive.
6
but we identified all as background objects
through follow-up proper motion observa-
tions. Figure 2 shows an example of such a
candidate, where you can see the very red
color in z-J, as the candidate (circled) is bare-
ly seen in z (top left image) but is very well
detected in J (top right image).
GeminiFocus
Figure 3 shows in shades of magenta the
average contrast map obtained for the sur-
vey. It shows the probability of detecting a
planet with a given mass between 1 and 13
M Jup as a function of the planet semi-major
axis. The survey reaches good completeness
for companions with masses down to 2 M Jup
January 2019