the optical, SUNBIRD aims to uncover CCSNs
that otherwise would remain hidden in the
dusty, crowded star-forming regions within
LIRGs. So far, in a relatively modest amount
of telescope time, the project has discov-
ered three CCSNs, and one other candidate,
all of which are near the centers of intense
star formation in LIRGs (Figure 4). This repre-
sents a very high discovery rate compared to
previous searches. The results indicate that
the majority of CCSNs that explode in such
galaxies have been missed as a result of dust
obscuration and inadequate image quality.
The work has been accepted for publication
in Monthly Notices of the Royal Astronomical
Society, and a preprint is available online.
OCTOBER 2017
A Super-distant, Superluminous
Supernova
Observations conducted with the Gemini
Multi-Object Spectrograph on the 8-meter
Gemini South telescope have confirmed that
a brilliant explosion more than three times
as bright as our Milky Way Galaxy is one of
the most distant supernovae ever studied.
The event, known as DES15E2mlf, occurred
about 3.5 billion years after the Big Bang, at
a period known as “cosmic high noon,” when
the rate of star formation in the Universe had
reached its peak.
DES15E2mlf was initially detected in Novem-
ber 2015 by the Dark Energy Survey (DES).
Follow-up observations at Gemini South
not only confirmed the object’s distance of
10 billion light years, but also revealed its
unusual nature. Previous observations of
superluminous supernovae show that they
typically reside in low-mass or dwarf galax-
ies, which tend to be less enriched in metals
than more massive galaxies. However, Uni-
versity of California Santa Cruz astronomers
Yen-Chen Pan and Ryan Foley, who led the
January 2018 / 2017 Year in Review
Gemini investigation as part of an inter-
national team of DES collaborators, found
that the host galaxy of DES15E2mlf, is a fair-
ly massive normal-looking galaxy, which
goes counter to current thinking.
While knowing that very massive stars
were exploding at that time is important,
the team would now like to know the rela-
tive rate of superluminous supernovae to
normal supernovae — to see if this atypi-
cal supernova is telling us something spe-
cial about that time 10 billion years ago.
It may be that at these earlier times in the
Universe’s history, even high-mass galax-
ies, like our Milky Way, may have had a low
enough metal content to create these ex-
traordinary stellar explosions.
Their findings appear in a paper published
June 13th in the Monthly Notices of the
Royal Astronomical Society.
New Class of Variable Stars
Confirmed
Astronomers using the Gemini Multi-Ob-
ject Spectrograph (GMOS) on the Gemini
South telescope have confirmed a new
class of variable stars. Called Blue Large-
Amplitude Pulsators (BLAPs), they are sig-
nificantly bluer than main sequence stars
of the same luminosity, demonstrating that
they are relatively hot. Pawel Pietrukowicz
(Warsaw University Observatory, Poland)
led the Gemini study, following the team’s
discovery of 14 candidate stars as part of
the Optical Gravitational Lensing Experi-
ment (OGLE) — a variability sky survey con-
ducted on the 1.3-meter Warsaw Telescope
at Las Campanas Observatory, Chile.
The team’s GMOS spectra on three of the
candidate BLAPs confirmed that these
stars are “low-mass giants” with helium-rich
atmospheres and high surface tempera-
tures of about 30,000 K, comparable with
GeminiFocus
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