Galaxy collision creates 'space triangle' in new Hubble image

Date:
February 23, 2022
Source:
NASA/Goddard Space Flight Center
Summary:
A spectacular head-on collision between two galaxies fueled the
unusual triangular-shaped star-birthing frenzy, as captured in a
new image from NASA's Hubble Space Telescope.



FULL STORY ==========================================================================
A spectacular head-on collision between two galaxies fueled the unusual triangular-shaped star-birthing frenzy, as captured in a new image from
NASA's Hubble Space Telescope.


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The interacting galaxy duo is collectively called Arp 143. The pair
contains the glittery, distorted, star-forming spiral galaxy NGC 2445
at right, along with its less flashy companion, NGC 2444 at left.

Astronomers suggest that the galaxies passed through each other, igniting
the uniquely shaped star-formation firestorm in NGC 2445, where thousands
of stars are bursting to life on the right-hand side of the image. This
galaxy is awash in starbirth because it is rich in gas, the fuel that
makes stars. However, it hasn't yet escaped the gravitational clutches
of its partner NGC 2444, shown on the left side of the image. The pair
is waging a cosmic tug-of-war, which NGC 2444 appears to be winning. The
galaxy has pulled gas from NGC 2445, forming the oddball triangle of
newly minted stars.

"Simulations show that head-on collisions between two galaxies is one way
of making rings of new stars," said astronomer Julianne Dalcanton of the Flatiron Institute's Center for Computational Astrophysics in New York
and the University of Washington in Seattle. "Therefore, rings of star formation are not uncommon. However, what's weird about this system is
that it's a triangle of star formation. Part of the reason for that shape
is that these galaxies are still so close to each other and NGC 2444 is
still holding on to the other galaxy gravitationally. NGC 2444 may also
have an invisible hot halo of gas that could help to pull NGC 2445's gas
away from its nucleus. So they're not completely free of each other yet,
and their unusual interaction is distorting the ring into this triangle."
NGC 2444 is also responsible for yanking taffy-like strands of gas from
its partner, stoking the streamers of young, blue stars that appear to
form a bridge between the two galaxies.

These streamers are among the first in what appears to be a wave of star formation that started on NGC 2445's outskirts and continued inward.

Researchers estimate the streamer stars were born between about 50 million
and 100 million years ago. But these infant stars are being left behind
as NGC 2445 continues to pull slowly away from NGC 2444.

Stars no older than 1 million to 2 million years are forming closer to
the center of NGC 2445. Hubble's keen sharpness reveals some individual
stars. They are the brightest and most massive in the galaxy. Most of the brilliant blue clumps are groupings of stars. The pink blobs are giant,
young, star clusters still enshrouded in dust and gas.

Although most of the action is happening in NGC 2445, it doesn't
mean the other half of the interacting pair has escaped unscathed. The gravitational tussle has stretched NGC 2444 into an odd shape. The galaxy contains old stars and no new starbirth because it lost its gas long ago,
well before this galactic encounter.

"This is a nearby example of the kinds of interactions that happened
long ago.

It's a fantastic sandbox to understand star formation and interacting galaxies," said Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland.

The Hubble Space Telescope is a project of international cooperation
between NASA and ESA (European Space Agency). NASA's Goddard Space
Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts
Hubble science operations.

STScI is operated for NASA by the Association of Universities for Research
in Astronomy in Washington, D.C.

========================================================================== Story Source: Materials provided by
NASA/Goddard_Space_Flight_Center. Original written by Donna Weaver
(STScI). Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
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YouTube_video:_Galaxy_Collision_Creates_'Space_Triangle'_in_New_Hubble
Image ==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2022/02/220223085823.htm

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