- 4592 - JAMES WEBB - finds Brown Dwarfs? - James Webb telescope finds 1st possible 'failed stars' beyond the Milky Way. It may have found dozens of elusive brown dwarfs tht are strange objects larger than planets but smaller than stars beyond the Milky Way for the first time ever.
---------------------------------------- 4592
- JAMES WEBB -
finds Brown Dwarfs?
-
- While the astronomers were zooming in on
the young star cluster NGC 602 in the nearby Small Magellanic Cloud (SMC), they
spotted what may be the first evidence of brown dwarfs ever seen outside the
Milky Way. Brown dwarfs, or "failed stars," are peculiar objects that
are bigger than the largest planets but not massive enough to sustain nuclear
fusion like the stars do.
-
- Brown dwarfs seem to form in the same way
as stars, they just don't capture enough mass to become a fully fledged
star. “NGC 602” is a roughly 3
million-year-old star-forming cluster on the outskirts of the SMC, a satellite
galaxy of the Milky Way that contains roughly 3 billion stars. (Our galaxy, in
comparison, contains an estimated 100 billion to 400 billion stars.)
-
- Orbiting about 200,000 light-years from
Earth, the SMC is one of the Milky Way's closest intergalactic neighbors and a
frequent target for astronomical studies.
Previous observations of NGC 602 taken with the Hubble Space Telescope
revealed that the cluster hosts a population of young, low-mass stars.
-
- Now, thanks to JWST's incredible
sensitivity to infrared light, astronomers have found stellar newborns that
reveal how much mass they have accumulated in their short lives.
-
- The results suggest that 64 stellar objects
within the cluster have masses ranging between 50 and 84 times that of Jupiter.
Brown dwarfs typically weigh between 13 and 75 Jupiter masses. This makes many of these objects prime
candidates to be the first brown dwarfs spotted beyond our galaxy.
-
- These failed stars appear to have formed in
much the same way as stars like the sun through the collapse of massive clouds
of gas and dust. However, for a collapsed cloud to become a star, it must
continue accumulating mass until it reaches an internal temperature and
pressure high enough to trigger hydrogen fusion at its core. It begins combining hydrogen atoms into
helium and releasing energy as light and heat in the process.
-
- Brown dwarfs never acquire enough mass to
sustain permanent fusion, leaving them larger than a planet but smaller and
dimmer than a star. This failure to ignite may be a common outcome in the
universe. Astronomers have discovered
about 3,000 brown dwarfs in the Milky Way but estimate that there may be as
many as 100 billion in our galaxy alone, potentially making them as common as
stars themselves.
-
- Studying this group of extragalactic failed
stars further could help clarify why so many stars seemingly fail to
ignite. These objects could also reveal
new insights about the early universe. NGC 602 is a young cluster containing
low abundances of elements heavier than hydrogen and helium, so its composition
is thought to be very similar to that of the ancient universe, before later
generations with the elements we see near Earth.
-
- By studying the young metal-poor brown
dwarfs newly discovered in NGC 602, we are getting closer to unlocking the
secrets of how stars and planets formed in the harsh conditions of the early
Universe.
-
-
October 30, 2024 JAMES
WEBB - finds Brown Dwarfs? 4592
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