Figure 10.
Composite image of
asteroid P/2010 A2
constructed from data
from the Gemini Multi-
Object Spectrograph
on Gemini North. The
team used this data
to compare against
models of the object’s
structure and dynamics.
peaked period of 11.36 +/- 0.02 hours. Figure
10 presents a composite from the imaging
data revealing the array of fragments and de-
bris used to determine the mass of the larg-
est fragment, which is about 80% of the sys-
tem’s mass; the other fragments and ejecta
make up the remaining 20%. All figures are
from the accepted paper scheduled for publi-
cation in The Astrophysical Journal Letters.
APRIL 2017
Figure 11.
Minimum ionizing
luminosity of extended
AGN-ionized clouds
along the projected
radius. These Hubble
Space Telescope data
show a luminosity
drop in the last 20,000
years before our direct
view of the nucleus,
characteristic for all
AGN of this study.
New Insights on Fading Active
Galactic Nuclei in Collaboration
with Galaxy Zoo
William C. Keel (University of Alabama) and
collaborators use Hα narrowband filters on
the Hubble Space Telescope (HST), in con-
junction with the Gemini Multi-Object Spec-
trograph integral field unit (GMOS IFU) on
the Gemini North telescope on Maunakea, to
observe a set of fading active galactic nuclei
(AGN). These AGN were first identified/classi-
fied as part of the Galaxy Zoo project — an
online citizen science project in which the
public help researchers deal with floods of
incoming data aimed at classifying galaxies.
This work focuses on nine AGN with ionized
gas clouds extending more than 10 kilopar-
secs from them. Because these clouds span
galaxy scales (or even larger) they can im-
plicitly tell us about the luminosity history
of the AGN. Based on this research, the nine
observed AGN appear to have experienced
a significant reduction in luminosity within
20,000 years or less (Figure 11).
The research team also uses GMOS IFU
spectra to measure line ratios in these re-
gions — to probe their ionization mecha-
nisms and look for kinematic evidence of
outflows marked by large (often bipolar)
velocity ranges or other phenomena.
The team’s results confirm what was hinted
at by earlier, and less complete data (by
the same team), that these fading AGN are
structurally different from radio-loud AGN,
which are dominated by outflows. Instead,
these fading AGN are dominated by rota-
tion and consist largely of externally illumi-
nated tidal debris (Figure 12); the Gemini
data show a shifting of the [O III] emission
line due to the gas cloud’s rotation.
This work appears in The Astrophysical Jour-
nal, and the paper can be found here.
Also read this Galaxy Zoo blog posting de-
scribing this work.
Rocky Planets Assembling in a
Dwarf Binary System
To date, almost all of the known planetary
systems that include a white dwarf are sin-
gle stars. Now, a team studying SDSS 1557
(a white dwarf and brown dwarf binary sys-
tem) using the Gemini South telescope and
the European Southern Observatory’s Very
Large Telescope, have made a surprising
46
GeminiFocus
January 2018 / 2017 Year in Review