Figure 2.
Artist’s concept of
what the view might
be like from inside the
TRAPPIST-1 exoplanetary
system, showing three
Earth-sized planets in
orbit around the lowmass star. This alien
planetary system is
located only 12 parsecs
away. Gemini South
telescope imaging, the
highest resolution images
ever taken of the star,
revealed no additional
stellar companions,
providing strong evidence
that three small (probably
rocky) planets orbit this
star.
Credit: Robert Hurt/JPL/
Caltech
Figure 3.
Detection limit
analysis for the June
22, 2016, GeminiSouth observation of
TRAPPIST-1. Detection
limits observed at 692
nm (top) and at 883
nm (bottom). The red
line represents the
relative 5σ limiting
magnitude as a function
of separation from 0.027
to 1.2 arcsecond. At the
distance of TRAPPIST-1,
these limits correspond
to 0.32–14.5 AU. The
two listed limiting
magnitudes given for
reference are for angular
separations of 0.1 and
0.2 arcsecond.
8
clude that the galaxy’s mass is approximately
1012 MSun, and that the total galaxy is 99.99%
dark matter. One specific problem this example presents is that the formation of stars
is predicted to have maximum efficiency at
this mass regime. Dragonfly 44, a confirmed
member of the Coma cluster exhibiting a regular morphology, has formed 100 times fewer
stars than expected. A Gemini press release
provides some more information
and links to high-resolution images;
full results are published in The Astrophysical Journal Letters.
planets around them would have short periods (of days) and be detectable with current
technology. At least two of the three known
planets in this case are very close to the star,
so too hot even to be in the habitable zone.
The orbit of the third planet is somewhat uncertain now. See the Gemini press release
and The Astrophysical Journal Letters for full
results.
Confirming Nearby
Exo-Earths
The Differential Speckle Survey
Instrument (DSSI) visited Gemini
South for the first time in June 2016
and is already delivering exciting
results, including the validation of
nearby Earth-like exoplanets. Previous observations using the TRAnsiting Planets and PlanetesImals Small
Telescope (TRAPPIST) had shown
variations in the light curve of the
star TRAPPIST-1, implying the presence of several Earth-sized planets (Figure 2). Steve Howell (NASA
Ames Research Center) and colleagues used the high-resolution
images from Gemini to confirm the
small size and mass of these suggested planets by ruling out the
presence of a very nearby companion. DSSI on Gemini provides the
highest resolution images available
to astronomers anywhere and here
achieved a resolution of 27 milliarcseconds, or 0.32 astronomical units
at the 12-parsec distance of TRAPPIST-1.
The host star, TRAPPIST-1, is a late M
dwarf. Such cool stars are interesting targets because any terrestrial
GeminiFocus
October 2016