- 4612 -
WEBB FINDS BROWN
DWARFS? - James Webb telescope finds 1st possible
'failed stars' beyond the Milky Way that could reveal new secrets of the early
universe. The Space Telescope may have
found dozens of elusive brown dwarfs which are strange objects larger than
planets but smaller than stars beyond
the Milky Way.
-
--------------------------------------- 4612
- WEBB FINDS
BROWN DWARFS?
-
- JWST
zooming in on the young star cluster “NGC 602” in the nearby Small
Magellanic Cloud (SMC), 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
stars.
-
- The observations, which include a new image
of the star cluster courtesy of JWST's Near Infrared Camera, reveal fresh
insight into how these strange failed stars form. 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.
-
- Previous observations of NGC 602 taken with
the Hubble Space Telescope revealed that the cluster hosts a population of
young, low-mass stars. Because of
JWST's incredible sensitivity to infrared light, astronomers have fleshed out
the picture of these stellar newborns, revealing precisely 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 making 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 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.
-
- 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 of
stars peppered with the panoply of 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.
-
-
November 18, 2024 WEBB FINDS
BROWN DWARFS? 4612
------------------------------------------------------------------------------------------
-------- Comments appreciated and Pass it on to
whomever is interested. ---
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for
copies or Index of all reviews
--- to:
------
jamesdetrick@comcast.net
------ “Jim Detrick” -----------
--------------------- --- Monday, November 18,
2024
---------------------------------
No comments:
Post a Comment