Sky & Telescope - March 2022 - 10

NEWS NOTES
200
LIGO-Virgo-KAGRA black holes
100
50
?
20
10
5
EM black holes
?
2
EM neutron stars
1
BLACK HOLES
Third Gravitational-wave Catalog Released
THE INTERNATIONAL TEAM associated
with three gravitational-wave projects
has unveiled results from their latest
observing run, adding 35 new events
and raising the total number to 90.
The catalog includes compact objects
caught colliding between November
2019 and March 2020. This run
included both Europe's Virgo and the
U.S.-based LIGO detectors. The Japanese
KAGRA project joined the fun for the
campaign's last two weeks.
Of the 35 pairs in the newest catalog,
32 were black hole mergers. There were
also two neutron star-black hole collisions
and one event of indeterminate
JUPITER
The Roots of the Great Red
Spot Run Deep
NASA'S JUNO MISSION has obtained
measurements that finally say just how
far down the Great Red Spot goes. The
deep roots of the centuries-long storm
could be a clue to its longevity.
Previous work using the microwave
radiometer aboard NASA's Juno spacecraft
demonstrated the storm was still
going strong 240 kilometers (150 miles)
below the cloudtops. Now, a study in
10 MARCH 2022 * SKY & TELESCOPE
pScientists have now detected 90 gravitational-wave
events. The dots indicate the masses of
the objects that merged and of the object they
created. (Pink and yellow dots are detections
from electromagnetic observations.)
type: It might have been a black hole
gnashing a neutron star, but chances
are the smaller object was a tiny black
hole 2.8 times the Sun's mass.
In a separate publication, the LVK
Collaboration analyzed 76 of the most
reliable events, upending some expectations
about black holes as a population.
Astronomers had predicted that they
wouldn't see objects between roughly 3
and 5 solar masses, and there is a drop
the October 28th Science puts a bottom
limit to its depth. Juno scientist Marzia
Parisi (JPL-Caltech) led an effort utilizing
two passes that had the spacecraft
zipping right over the Great Red Spot.
The team also analyzed data from
another 10 passes.
The spacecraft's path changed ever
so slightly over the cyclone because of
the uneven distribution of mass in the
clouds below. By measuring deviations
to Juno's expected path to within 0.01
millimeter per second, Parisi and colleagues
showed that the Great Red Spot
in the number of objects just above
2 solar masses. But the gravitationalwave
data don't show a hard upper edge,
nor does this putative gap appear to be
totally empty.
Astronomers had also thought that
stars large enough to make black holes
between 50 and 120 solar masses
should tear themselves apart, leaving no
remnant when they die. But the observations
reveal black holes in this region,
too: Although the latest gravitationalwave
data do show a drop-off above 40
Suns or so, it's not precipitous.
The detectors will return for a fourth
observing run in late 2022, when further
upgrades may increase the number
of detections by a factor of three.
¢CAMILLE M. CARLISLE
JunoCam captured this image of Jupiter's
south temperate belt and Great Red Spot
on Dec. 30, 2020.
LIGO-Virgo-KAGRA
neutron stars
?
Solar masses
GRAVITATIONAL-WAVE EVENTS: LIGO-VIRGO / AARON GELLER / NORTHWESTERN
UNIVERSITY; JUPITER: NASA / JPL-CALTECH / SWRI / MSSS; IMAGE PROCESSING:
NAVANEETH KRISHNAN S / CC BY
Sky & Telescope - March 2022

Table of Contents for the Digital Edition of Sky & Telescope - March 2022
