ASTRONEWS
LESS LOSS. Direct observations of the ozone hole over the past 20 years show that there is now 20 percent less
ozone depletion each Antarctic winter than there was in 2005.
DID THE SOLAR SYSTEM FORM
IN A BUBBLE?
Molecular
cloud
Time
1.27 Myr
Wind
bubble
Time
2.49 Myr
Time Time
4.58 Myr 4.38 Myr
1 Myr = 1,000,000 years
BUBBLE BIRTH. University of Chicago researchers are suggesting the solar
system may have formed in a densely shelled bubble within a giant Wolf-Rayet
star. According to their theory, as the dying star shed its outer layers — a normal
end-of-life process for massive stars — strong stellar winds plowed through the
loosely held cloak of material, forming bubbles packed with gas and dust. Such
bubbles are ideal for birthing stars, the researchers say; they estimate this process
could account for the formation of 1 to 16 percent of all Sun-like stars. — J.P.
STRANGE NEIGHBORHOOD. New results show that the fast radio burst
FRB 121102 comes from an extreme environment with highly magnetized, dense
plasma. One possibility is a magnetized nebula around or near a pulsar, such as
the one around the Crab Pulsar, pictured here in X-rays and optical light.
FRB resides near a
strong magnetic field
MILLION BILLION
The mass contained in the “El Gordo”
galaxy cluster, in solar masses.
3
A globular cluster’s silent black hole
ODD ORBIT. Using ESO’s MUSE instrument on the Very Large Telescope in
Chile, astronomers discovered a star zipping around the heart of the globular
cluster NGC 3201. By analyzing the star’s exceptionally bizarre orbital motion,
they determined that an inactive (not actively accreting material) stellar-mass
black hole lurks within the cluster, imagined in this artist’s concept. This is
the first inactive black hole discovered in a globular cluster, and the first
detection of a stellar-mass black hole made purely by measuring its gravitational
influence on other stars. — J.P.
Dense
shell
ASTRONOMY:
Ionized
region
Fast radio bursts (FRBs) are brief
but powerful blasts of radio ener-
gy thought to come from neutron
stars. The sole repeating FRB,
FRB 121102, has already allowed
astronomers to pinpoint its loca-
tion in a dwarf galaxy 3 billion
light-years away. Now, new
measurements showing that the
bursts are influenced by a nearby
strong magnetic field are helping
astronomers further narrow down
its location within the galaxy.
The results come from a study
conducted with the Arecibo
Observatory in Puerto Rico and
the Green Bank Telescope in West
Virginia. In the study, published
January 11 in Nature, astronomers
measured the polarization of the
bursts coming from FRB 121102.
Polarization measures the
degree of alignment between the
magnetic and electric fields of
light (in this case, radio emission).
When polarized emission passes
through or near a strong mag-
netic field, its alignment can
become twisted, a process called
Faraday rotation. Bursts from
FRB 121102 show the strongest
Faraday rotation ever observed
from an FRB, indicating its source
must sit in a highly magnetized,
plasma-rich region of space.
“This sort of enormous Faraday
rotation is extremely rare. … We
realized it was a huge clue about
where this bizarre source resides,”
said team member Victoria Kaspi of
McGill University in a press release.
Astronomers now have two
theories for the environment
around FRB 121102: Either its
source is near the galaxy’s central
supermassive black hole, or it is
sitting inside a nebula magne-
tized by winds from a powerful
pulsar, such as a scaled-up ver-
sion of the Crab Nebula.
The new findings leave astron-
omers wondering whether FRBs
could be a product of their envi-
ronment. “If you have an extreme
object in an extreme environ-
ment, is that just a coincidence?
FRBs have these huge explosions
in radio waves, and we don’t
know why that occurs. Maybe this
is a clue to the mechanism that
produces these explosions,” said
Kaspi. — A.K.
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