Sky & Telescope - May 2020 - 11

IN BRIEF

FAST RADIO BURSTS

New Radio Flash "Repeater" Pinned Down
RECENT OBSERVATIONS have pin-

pointed the location of a ﬁfth fast
radio burst (FRB), shedding light on the
environments that create these brief but
powerful radio-wave ﬂashes.
Benito Marcote (Joint Institute for
VLBI, The Netherlands) announced at
the American Astronomical Society
meeting in Honolulu that he and his
colleagues have pinned down another
radio ﬂash, the second repeating FRB
to have a known location. The result
appears in the January 9th Nature.
The Canadian Hydrogen Intensity Mapping Experiment (CHIME)
telescope discovered the radio ﬂash,
referred to as FRB 180916, in 2018. As
the source continued to emit ﬂashes,
eight radio dishes of the European
VLBI Network pinpointed the source to
the outskirts of a spiral galaxy, whose
light traveled almost half a billion
years to Earth. The astronomers used
the 8.1-meter Gemini North telescope
on Mauna Kea, Hawai'i, to image the
region: Whatever was producing the
radio ﬂashes had a nursery of newborn
stars for company.

This environment is similar to the
star-forming region hosting the ﬁrst
repeater, but it contrasts with the locations of single FRB ﬂashes, Marcote
says. All those have been localized to
massive galaxies with low star-formation rates. The ﬁnd suggests that repeating and non-repeating FRBs might have
different origins.
Yet astronomers are still far from
understanding what those origins are.
New results from the CHIME collaboration, to appear in the Astrophysical
Journal Letters, will help: The unique
telescope discovered nine additional
repeaters in 2019 observations, but
what's more, the collaboration is also
still analyzing some 700 additional FRB
detections, to be published in a forthcoming catalog.
"By the end of 2020, we will have
more than 1,000 FRBs, at least a few
dozen that will be precisely localized,
and we can answer some questions,"
predicts study coauthor Jason Hessels
(ASTRON, The Netherlands). "Or at
least we'll have some new questions."
■ MONICA YOUNG

G EMINI OBSERVATORY / NSF'S N ATION A L OIR
ASTRONO M Y RESE A RCH L A BOR ATORY / AUR A

q A star-forming region in a spiral galaxy hosts FRB 180916.

Most Planets Lost in
Globular Clusters
At most one-fifth of planetary systems
around stars in globular clusters may survive, student Melissa Cashion (Texas A&M
University) reported at the recent meeting
of the American Astronomical Society in
Honolulu. Globular clusters are dense,
long-lived clusters of many thousands of
stars, and it's unclear how planets fare
in such an environment. Cashion and
her colleagues simulated clusters with
800,000 stars, with some fraction of them
beginning with a Jupiter-mass planet
circling at the same distance that Jupiter
circles the Sun. The astronomers then
followed the stars and their planets over
12 billion years, watching things unfold.
Most planetary systems were destroyed
in the first billion years, they found, with
planets jumping to different stars - or
in rare cases, black holes. Some planets
wound up permanently circling another
companion, but most went rogue, wandering the cluster starless or even ejected
from the cluster entirely. A 5% to 20%
survival rate is "not too bad, considering
all the chaos," Cashion says.
■ CAMILLE M. CARLISLE

New Horizons Still
Exploring the Kuiper Belt
Ever since the New Horizons spacecraft
passed Pluto and set its sights on Arrokoth (formerly 2014 MU69), its team has
been taking pictures of other, faraway
worlds in the Kuiper Belt. Although these
small bodies have been nothing but blurry
blobs as the craft passed them - at
distances from one-tenth to 1 astronomical unit - scientists are still able to learn
about their shapes. The team watches
how the worlds change in brightness
over time as they're seen from different
angles, then combines that information
with Earth-based observations. This work
indicates that Kuiper Belt objects have a
variety of shapes, Simon Porter (Southwest Research Institute) and colleagues
reported at the meeting of the American
Astronomical Society in Honolulu. One,
called 2011 JY31, is probably spherical; two others appear to be conjoined
twins, like Arrokoth. A third looks like a
binary system. The results add to growing
evidence that binaries and contact binaries might be common in the outer solar
system (S&T: Feb. 2020, p. 34).
■ CAMILLE M. CARLISLE
s k y a n d t e l e s c o p e . o r g * M AY 2 0 2 0

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Sky & Telescope - May 2020

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