Figure 10.
to the nearby host star of interest. Multiple
observations of the candidate objects can
distinguish these scenarios, and unfortunately, most of the time the less-interesting
chance alignment is the conclusion. Another
important detail of the work is to determine
the ages of the stars. Because age has a
strong effect on the appearance of planets
and other low-mass companions — they are
brighter and hotter when recently formed,
and fade and cool over time — the inferred
planet properties are sensitive to stellar age.
Contours show the
probability that a star
of given mass has a
giant planet at the
given semi-major axis
location.
Michael Liu (University of Hawai‘i) and a large
international team from across the Gemini
partnership and beyond used NICI for the
Gemini NICI Planet-Finding Campaign, the
largest, deepest systematic search for planets through direct imaging. The result is that
fewer stars than previously expected show
evidence for planets, which will require
some updates to theories of planet formation and survival. While some low-mass
(substellar) companion objects have been
detected, the Campaign did not image any
unknown planets.
The first comprehensive result from the Campaign considers young B and A stars, of about
twice the mass of the Sun. Based on observations of 70 of them, Eric Nielsen, who led
this effort, concluded that fewer than 10 percent of these stars have giant planets (with
masses greater than 10 times that of Jupiter)
at distances of about 40–650 astronomical
units (AU; the average Earth-Sun distance)
from Z\