Astronomy - USA 2021-04)

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10 ASTRONOMY • APRIL 2021


Galaxies, like people, change as they age.
Young galaxies are full of gas and dust
that fuel intense star formation, while
older galaxies are devoid of this material
and can’t make new suns.
What prompts the change? All massive
galaxies host supermassive black holes
in their centers. These black holes grow
by eating gas and dust, belching out huge
amounts of energy in the process. That
energy heats the remaining gas through-
out the galaxy, preventing it from cooling
and clumping together to form more stars
— quenching star formation and starting
a galaxy down the path of aging.
Now, astronomers using NASA’s
Stratospheric Observatory for Infrared
Astronomy (SOFIA) have gotten a glimpse
at a unique time in a galaxy’s life. The
galaxy CQ 4479, which is more than
5.25 billion light-years away, has both an
actively feeding black hole and a healthy
rate of star formation, making 100 solar
masses’ worth of stars per year. The dis-
covery was published November 6 in The
Astrophysical Journal.

CQ 4479 offers a peek into “a very
limited time window where you can see
both the black hole growing and the
stars surrounding it growing at the same
time,” said Kevin Cooke, a postdoctoral
researcher at the University of Kansas
(KU) in Lawrence, Kansas, and lead
author of the study, in a press release.
“I think this is a galaxy undergoing
a midlife crisis,” said co-author Allison
Kirkpatrick, also at KU. “It’s going
through one last burst of star formation.
... It’s forming a few more stars now, and
the thing that’s ultimately going to kill it
is starting to kick in.”
The researchers next want to
observe CQ 4479 with the Atacama
Large Millimeter/submillimeter array,
as well as the upcoming James Webb
Space Telescope. Studying galaxies
transitioning from young and active to
old and quiescent will help us better
understand galaxy evolution as a whole,
as well as improve our picture of how
the Milky Way formed and how it will
age. — A.K.

Astronomers spot a galaxy


in midlife crisis


A HUBBLE


CHIAROSCURO


MASTERPIECE


Countless artists throughout
time have strived to capture
the beauty of nature in their
work. But Hubble does that
with ease. Located some 1,
light-years from Earth, the
stunning Herbig-Haro Jet HH
24 contains a newborn star
forming within a giant cloud
of cool molecular hydrogen.
As the cloud collapses due to
gravity, it forms a thick disk of
rotating material around the
star. And as the star gobbles
up this superheated material,
some of it escapes as jets
that shoot from the star’s
poles, heating nearby gas to
thousands of degrees and light-
ing up this stunning scene.
Eventually, this region will
settle down enough for planets
to likely be born from the disk
of material surrounding the
young star. — H.R.M.

2.32 x 10



  • m/s


2


The acceleration of the solar system around the Milky Way,


as measured by the Gaia Space Telescope.


QUANTUM GRAVITY


TRANSITORY
PHASE. CQ 4479,
shown in this
artist’s concept,
has both an
actively growing
supermassive
black hole
(center) and cold
gas (orange-
brown, outer
edges) that is still
forming stars.
NASA/DANIEL RUTTER

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