Figure 5.
Evidence for
a hot toroidal
phase in the early
circumstellar
envelope of our
own Solar System
(right) has emerged
from data from
the Stardust
probe (left), which
showed crystalline
silicates that were
likely annealed
at temperatures
around ~ 1000 K.
Abraham and
collaborators [no
relation to the first
author] described
a scenario for such
annealing in a 2009
Nature paper.
Gemini Observatory/
AURA artwork by
Lynette Cook.
the most likely explanation for the 2-5-micron excess seen in Figure 3 is the contribution from thousands of flared circumstellar
disks around massive young stellar objects
seen in the integrated light of these highredshift galaxies.
Dawn of a New Era?
It seems natural to suppose that the presence
of circumstellar disks around massive stars at
high redshifts would also imply the presence
of disks around less massive stars. Of course,
we would also expect planets to form around
these less massive systems. Therefore this
2-5-micron excess might present us with an
opportunity to probe the formation of planets (as seen in their total integrated light) at
cosmic epochs even before our own Solar
System formed (Figure 5).
This is a very indirect argument of course,
but it’s a rather intriguing possibility. Perhaps
the most interesting follow-up measurement
from a cosmological standpoint would be the
measurement of something like the cosmic
evolution of the volume-averaged planet formation rate density. Could this be the dawn of
a new subject area in astrophysics: the study
of extragalactic planet formation?
12
GeminiFocus
Roberto Abraham is a professor of astronomy and
Associate Chair of the Astronomy and Astrophysics Department at the University of Toronto. His email address is: [email protected]
Karl Glazebrook is a university distinguished professor at the Centre for Astrophysics and Supercomputing, Swinburne University of Technology,
in Australia. His e-mail address is:
[email protected]
Pat McCarthy is an astronomer at the Carnegie
Observatories and Director of the Giant Magellan
Telescope Project. His e-mail address is:
[email protected]
The Gemini Deep Deep Survey team is:
Co-I’s: David Crampton (HIA), Rick Murowinski
(HIA), Sandra Savaglio (MPA), Damien Le Borgne
(IAP, France), Isobel Hook (Oxford), Inger Jorgensen (Gemini), Kathy Roth (Gemini), Ray Carlberg (Toronto), Ron Marzke (SFSU), Hsiao-Wen
Chen (Chicago), Stephanie Juneau (Arizona), Erin
Mentuch (Texas), Andy Green (Swinburne), Ivana
Damjanov (Toronto), Greg Poole (Swinburne), Evelyn Caris (Swinburne) and Anne-Marie Weijmans
(Toronto).
June2012