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Jupiter’s

polar

cyclones

don’t

add up

Novae result when a white

dwarf, the remnant of a

Sun-like star, suddenly and

briefly reignites fusion in its

thin atmosphere as it pulls

mass from a companion

star. These events highlight

the dynamic interactions

that occur in binary star

systems, and astronomers

recently saw one of the

brightest yet.

The nova, SMCN 2016-

10a, occurred in October

2016 in the Small

Magellanic Cloud (SMC),

200,000 light-years away. It

is the brightest ever seen in

the SMC or any galaxy

other than the Milky Way.

Several ground-based tele-

scopes saw the event in

conjunction with NASA’s

orbiting Swift Gamma-Ray

Burst Mission. A paper on

the observations, led by

Elias Aydi of the South

African Astronomical

Observatory and the

University of Cape Town,

will appear in Monthly

Notices of the Royal

Astronomical Society.

“Observing the nova in

different wavelengths

using world-class tele-

scopes such as Swift and

the Southern African Large

Telescope helps us reveal

the condition of matter in

nova ejecta as if it were

nearby,” collaborator Paul

Kuin of the Mullard Space

Science Laboratory,

University College London,

said in a press release.

That close-up view

shows the white dwarf

“is close to the theoretical

maximum [mass],” said

Kim Page, who led the

X-ray analysis from the

University of Leicester.

That maximum, called the

Chandrasekhar limit, states

that a white dwarf over

1.4 times our Sun’s mass

will tear itself apart. For

SMCN 2016-10a, “continued

accretion might cause it

eventually to be totally

destroyed in a supernova

explosion,” said Page.

Not all novae are the

same. Some flare quickly,

others slowly; some repeat,

while others don’t.

Understanding these

events lets astronomers

look deeper into the work-

ings of stars. Given that

SMCN 2016-10a also seems

poised to go supernova

someday, it’s providing

astronomers with a unique

view of the lead-up to a

white dwarf’s ultimate

demise. — Alison Klesman

QUICK TAKES

PLANET BUILDING

Under favorable conditions,

ice around a star can melt and

stick together as bigger

particles, creating the building

blocks of planets.

• RING IT
  Gravitational influences from
  seven moons of Saturn — six
  small moons and the large
  moon Mimas — keep the
  A ring from falling apart.


• 
  

  COLD WATER
  In the vacuum of space, frozen
  water ice can behave like a
  thick molasses when exposed
  to ultraviolet radiation.

  
  


• 
  

  LUNAR AIR
  Volcanic eruptions produced a
  moderately thick atmosphere
  around the Moon 3 billion to
  4 billion years ago.

  
  


• 
  

  GLOBAL LIGHT SHOW
  In September, a solar storm
  struck Mars, doubling
  radiation on its surface and
  creating a global aurora.

  
  


• 
  

  GREEN THUMB
  Tending a small garden on the
  International Space Station
  raises the moods of its
  astronauts, according to a
  study in Open Agriculture.

  
  


• 
  

  OXYGEN-STARVED
  A dwarf galaxy in Lynx with
  low levels of oxygen could
  help us understand the
  chemistry of the early universe.

  
  


• 
  

  ZAP!
  Solar storms may generate
  electrical fields around Phobos
  and Deimos, affecting future
  human exploration of Mars.

  
  


• 
  

  MAUNA KEA
  The Thirty Meter Telescope’s
  construction permit has been
  reinstated, despite native
  Hawaiians’ protests that it will
  be built on sacred ground.

  
  


• 
  

  HIT THE BRAKES
  Comet 41P/Tuttle-Giacobini-
  Kresak’s rotation rate slowed
  drastically as it swept by Earth
  in spring 2017, going from
  24 to 48 hours.

  
  


• 
  

  NO BOOM
  The IceCube neutrino detector
  found no neutrino emissions
  from fast radio bursts, ruling
  out gamma-ray bursts and
  black holes as possible sources
  of these events. — J.W.

  
  

ARTIFICIAL EYE ON THE SKY. An artificial intelligence algorithm was used to spot 56 gravitational lensing

candidates in a vast field of stars and galaxies.

Astronomers see brightest extragalactic nova

NASA/JPL-CALTECH/S

WRI/MSSS/BETSY ASHER HALL/GERVASIO ROBLES

OGLE SURVEY

HERE TODAY. The brightest nova seen in a galaxy other than

our own exploded in the Small Magellanic Cloud in October 2016

(right). Prior to the nova (left), the patch of sky was unremarkable.

GOING IN CIRCLES.

NASA’s Juno spacecraft

continues to reveal more

of Jupiter’s long-kept

secrets as it swings

around our solar system’s

largest planet once every

53 days. Among the

mysteries are the clusters

of cyclones that swarm

the gas giant’s poles,

seen as oval-shaped

features in this image of

Jupiter’s south pole from

an altitude of 32,

miles (52,000 kilometers).

These features have

confounded scientists

because they shouldn’t

be able to form amid

the strong polar winds.

Currently, Jupiter sports

eight of these storms

around its north pole

and five around its

south pole; scientists are

working to understand

how they formed and

why the number of

cyclones differs between

the two poles. — A.K.