- 4522 - THE EARLIEST STARS - we are beginning to see them? - Wherever the JWST looks in space, matter and energy are interacting in spectacular displays. The Webb reveals more detail in these interactions than any other telescope because it can see through dense gas and dust that cloak many objects. Webb uses Infrared light that is not detected by optical telescopes.
------------------------- 4522 - THE EARLIEST STARS - we are beginning to see them?
- JWST spots a young protostar only 100,000
years old. The star is named “L1527”,
and at this young age, it’s still is in the molecular cloud that spawned it.
This is one of the reasons NASA built the JWST. The telescope can see through dust and gas
to reveal the earliest stages of star formation.
-
- The image was captured with MIRI, the
Mid-Infrared Instrument. The young protostar is at the heart of it all, and
it’s still growing. It’s accumulating mass from the protoplanetary disk that
surrounds it.
-
- The protostar isn’t a main-sequence star,
so it’s not undergoing fusion like the Sun is. There may be a small amount of
deuterium fusion in its core, but it generates energy in a different way. As
the star’s gravitational power draws material nearer, the material is
compressed and heats up. More energy comes from shockwaves generated by
incoming material that collides with existing gas. This is the energy that
lights up the star and its surroundings inside the giant molecular cloud that
spawned it.
-
- As young protostars accumulate mass, they
generate powerful magnetic fields. Combined with the star’s rotation, these
fields drive matter away from the star. So, as a protostar acquires mass, it
also ejects some of it back into space in spectacular hourglass-shaped jets
that come from the star’s poles. These jets create visible bow shocks in the
matter around the star, which are the filamentary structures.
-
- There are “polycyclic aromatic
hydrocarbons” (PAHs) in the star’s environment. They’re organic compounds
abundant throughout the Universe that may have contributed to the appearance of
life.
-
- The red region in the center is a thick
layer of gas and dust surrounding the young star, lit up by the star’s energy.
The region between is a mixture of materials. There are more PAHs here, as well
as ionized gases like neon and other hydrocarbons.
-
- The JWST captured the image of L1527 with
its Near-Infrared Camera (NIRCam). The upper central region displays
bubble-like shapes due to stellar “burps,” or sporadic ejections. The different
colors are from layers of dust. The more dust there is, the less blue light
escapes. The orange/red regions are thicker dust than the blue regions.
-
- This beautiful display of matter and energy interacting
is transient. Over time, the protostar’s powerful outflows will clear its
surroundings of much of the gas and dust, though it’ll still have its
protoplanetary disk. Eventually, the star will become a main sequence star,
easily seen without its veil of gas and dust. By that time, the star’s
planetary system will be taking shape.
-
- There are unanswered questions about
protostar formation, and one of the JWST’s main science goals is star
formation. Astrophysicists don’t know
exactly how and when fusion is triggered, and a protostar becomes a
main-sequence star.
-
- Though astronomers know there are powerful
magnetic fields around protostars, they don’t know exactly how they form and
what role they play in the star’s collapse and rotation.
-
- It recently confirmed that jets from young
stars are aligned because of the star’s rotation and magnetic fields, something
supported by theory but not confirmed by observations until now.
-
- There are also uncertainties about how
binary stars form. Do they form the same way solitary stars do? Why are so many
stars binaries?
-
- The exact nature of the events that trigger
star formation is also unclear. Shockwaves from supernovae can trigger star
birth, but what about in other cases? Is it just a matter of density?
-
- The answers to these questions will be
incremental. With its ability to see more detail in the young stars and the
clouds of swirling gas and dust that enshroud them, the JWST is making progress
one image at a time.
-
-
July 7, 2024 THE
EARLIEST STARS - we are beginning to see them? 4522
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--------------------- --- Tuesday, July 9, 2024
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