John Blakeslee and Peter Michaud
Science Highlights
Another year of ground-breaking science at Gemini demonstrates
how the Observatory’s diverse capabilities, flexibility, innovation,
and efficiencies lead to many wide-ranging, and high-impact
science results and discoveries.
JANUARY 2018
The Most Distant Kinematically Confirmed Spiral Galaxy
A team of astronomers using the Near-infrared Integral Field Spectrometer (NIFS) on Gem-
ini North have confirmed the most distant kinematically confirmed spiral known to date.
Spiral galaxies like the Milky Way have multiple structural components that formed at dis-
tinct times in the galaxy’s evolutionary history. These components include the stellar halo,
bulge, gas-poor thick disk, and gas-rich thin disk. Based on the maximum ages of their
constituent stars, the disk components, which are emblematic of spirals and participate
in ordered rotation about the Galactic center, are the least ancient parts of the Milky Way.
The thick disk appears to date from about 10 billion years ago, while the thin disk began
forming 2 or 3 billion years after that. If the Milky Way is typical, then we should not expect
to be able to identify many spiral galaxies at distances beyond about 10 billion light years,
or a redshift z beyond about 2.
A decade ago, Hubble images of the massive cluster of galaxies Abell 1689, a powerful
gravitational lens, showed a highly magnified background galaxy, designated A1689B11,
displaying spiral structure. Soon afterwards, its redshift was measured to be z = 2.5, imply-
ing a distance of 11 billion light years. This made it the most distant galaxy that appeared
to be spiral in nature and indicated that spirals existed less than 3 billion years after the
January 2018 / 2017 Year in Review
GeminiFocus
37