Peter Michaud
Science Highlights
Gemini Planet Imager observations of exoplanet 51 Eridani b help
support cold-start giant planet formation; GeMS-GSAOI data on the
proper motion of stars in the Pyxis globular cluster set a lower limit
for the Milky Way’s mass of 950 million Suns; and finally, Gemini
Multi-Object Spectrograph (GMOS) data from Gemini North help to
characterize the active fragmented asteroid P/2010 A2.
GPI Data Hint at Cold-Start Giant Planet Formation
Figure 1.
New research on the first exoplanet dis-
covered using the Gemini Planet Imager
(GPI) — 51 Eridani b — hints that it may
have formed by the collapse of icy disk
materials followed by the accretion of a
thick gas atmosphere, much like that de-
scribed in the cold-start model.
GPI images in
the K1, K2, LP,
and MS bands;
the emission
of the host star
was blocked. The
exoplanet 51 Eri b
is indicated by an
arrow. Located
about 100 light
years from Earth,
Exoplanet 51
Eri b is between
2–10 times the
mass of Jupiter.
Two main scenarios of giant planet forma-
tion exist: hot start and cold start. In the
hot-start model, gas giants form directly
via the rapid collapse of a gaseous proto-
planetary disk. In the cold-start scenario,
a gas-giant begins as a core that forms
very early on from planetesimal agglom-
erations before collecting the plentiful gas
around it.
12
GeminiFocus
July 2017