- 4225 -
GAMMA RAY BURSTS
- observed creating elements
needed for life. James Webb Space
Telescope used to observe an exceptionally bright gamma-ray burst, GRB 230307A,
and its associated kilonova. Kilonovas
are an explosion produced by a neutron star merging with either a black hole or
with another neutron star. They are
extremely rare, making it difficult to observe these events.
-
--------------------- 4225 - GAMMA RAY BURSTS -
- The highly
sensitive infrared capabilities of Webb helped scientists identify the home
address of the two neutron stars that created the kilonova. They observed the creation of rare chemical
elements in the second-brightest gamma-ray burst ever seen, casting new light
on how heavy elements are made.
-
- The exceptionally
bright gamma-ray burst GRB 230307A was caused by a neutron star merger. The
explosion was observed using an array of ground and space-based telescopes,
including NASA's James Webb Space Telescope, Fermi Gamma-ray Space Telescope,
and Neil Gehrels Swift Observatory.
-
- They found the
heavy chemical element tellurium, in the aftermath of the explosion. Other elements such as iodine and thorium,
which are needed to sustain life on Earth, are also likely to be among the
material ejected by the explosion.
-
- Gamma-ray bursts
come from powerful jets traveling at almost the speed of light, in this case
driven by a collision between two neutron stars. These stars spent several
billion years spiraling towards one another before colliding to produce the
gamma-ray burst we observed in March, 2021.
-
- The merger site is
the approximate length of the Milky Way (about 120,000 light-years) outside of
their home galaxy, meaning they must have been launched out together.
-
- Colliding neutron
stars provide the conditions needed to synthesize very heavy elements, and the
radioactive glow of these new elements powered the kilonova detected as the
blast faded. Kilonovae are extremely rare and very difficult to observe.
-
- GRB 230307A was
one of the brightest gamma-ray bursts ever observed, over a million times
brighter than the entire Milky Way galaxy combined. This is the second time
individual heavy elements have been detected using spectroscopic observations
after a neutron star merger, providing invaluable insight into how these vital
building blocks needed for life are formed.
-
- GRB 230307A lasted
for 200 seconds, a long-duration
gamma-ray burst. This is unusual as short gamma-ray bursts, which last less
than two seconds, are more commonly caused by neutron star mergers. Long
gamma-ray bursts like this one are usually caused by the explosive death of a
massive star.
-
- Until recently,
astronomers didn't think mergers could power gamma-ray bursts for more than two
seconds. Astronomers need to develop a
better understanding of what drives them and whether even heavier elements are
being created.
-
- Last year, on
October 9, 2019, scientists witnessed sprouting from the darkness between
stars, an abundance of deep space X-rays started to flood observatories. These
signals appeared to be connected to an immensely bright event happening in our
galaxy known as a gamma-ray burst (GRB).
GRB's are an outpouring of highly energetic particles linked to things
like star explosions and black hole births.
-
- This event was
dramatic enough at first blush. It was speculated to be the brightest GRB since
the start of human civilization and exhibit photons that hold more energy than
the Large Hadron Collider produces. GRB
221009A “BOAT”, short for
"Brightest Of All Time. Something
even more stunning about the BOAT is it didn't actually originate from the
Milky Way. BOAT came from a galaxy
behind our own.
-
- The
seven-minute-long burst (still detectable for 10 hours afterward) led to large
"variations" in Earth's atmosphere.
These variations seemed to be found in our planet's upper ionosphere,
the barrier between us and outer space. If true, this would mark the first time
we have seen a GRB impact this region. Astronomer have been measuring gamma-ray
bursts since the 1960s, and this is the strongest ever measured.
-
- There has been a
great debate about the possible consequences of a gamma-ray burst in our own
galaxy. Earth's atmosphere contains a
few layers, and the ionosphere sits in the uppermost section, stretching
between about 31 miles and 590 miles in
altitude. -
-
- Anywhere above 217
miles in altitude is considered the top half. And, all over the ionosphere lie
charged particles, or ions. These
disturbances/variations/perturbations
essentially refer to a change in the upper atmosphere's electric field.
That means all those ionospheric charged particles are directly affected.
Ionosphere disturbances like this are usually associated with energetic
particle events originating from our own sun but the BOAT's interference was
the result of an exploding star sitting almost two billion light-years away.
-
- Statistically
speaking, a GRB as bright as this should arrive at our planet just once every
10,000 years. This GRB activated
lightning detectors in India, alerted instruments in Germany, sprayed evidence
of its photon flux over Asia and parts of Australia and even cast a lingering
afterglow.
-
- BOAT affected some
of the lower layers of the ionosphere situated just tens of kilometers above
our planet's surface, leaving an imprint comparable to that of a major solar
flare.
-
- Analyzing the
effects of the blast could provide information about the mass extinctions in
Earth’s history. An eruption like BOAT
could bring about the end of humanity.
This eruption could offer us some insight into what would happen if a
nearby, actually threatening GRB impacted our planet. It could be able to
abruptly increase the atmospheric ionization, that might deplete stratospheric
ozone on a global scale.
-
- The ozone layer can
be thought of as Earth's sunscreen, protecting our planet's inhabitants from
harmful ultraviolet rays emanating from the sun. If our bodies sop up too many
of those rays, that can lead to things like an increased risk of cancer and
cataracts. If plants are exposed to too much UV, many of them will die.
-
- Astronomers
continue to look into the BOAT' cause. It's a slightly confusing one. The James
Webb Space Telescope and Hubble Space Telescope teams, for instance, tried
their hand at the matter, but the search came up empty, as neither could
pinpoint the aftermath of a star explosion in the BOAT's patch of the cosmos.
-
- There's also a lot
to study with those original BOAT X-ray signals, as the wavelengths had to
travel across the vast expanse of space before reaching us, crossing through
dust clouds and other phenomena out in the universe and picking up valuable
information along the way — ready for humans to decode.
-
-
November 16, 2023 GAMMA RAY
BURSTS 4225
------------------------------------------------------------------------------------------
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