- 4283 - CLOSEST SUPOERNOVA - The closest supernova seen in the modern era is being examined by the James Webb Space Telescope.
-------------------------- 4283 - CLOSEST SUPOERNOVA
- In 1572, Tycho Brahe
noticed a new star in the constellation Cassiopeia. It was the first supernova
to be observed in detail by Western astronomers and became known as Tycho’s
Supernova.
-
- Earlier supernovae
had been observed by Chinese and Japanese astronomers, but Tycho’s observations
demonstrated to the Catholic world that the stars were not constant and
unchanging as Aristotle presumed.
-
- Just three decades
later, in 1604, Johannes Kepler watched a supernova in the constellation
Ophiuchus brighten and fade. There have been no observed supernovae in the
Milky Way since then.
-
- More than three
centuries passed. Galileo pointed his first telescopes to the heavens.
Astrophotography revolutionized our view of the heavens, as did radio
astronomy. We launched telescopes into space, landed on the Moon, and sent
robotic probes to the outer solar system. But there were no nearby supernovae
to observe with our clever tools.
-
- Until February
1987, when a supernova appeared in the Large Magellanic Cloud. Known as “SN
1987a”, it reached a maximum apparent magnitude of about 3. It is the only
naked-eye supernova to occur within the era of modern astronomy.
-
- In cosmological
terms, SN 1987a is right in our backyard, only 168,000 light-years away. It has
been studied over the years by both land-based and space-based telescopes, and
recently the James Webb Space Telescope has taken a closer look. The results
tell us much about the rare supernova but also raise a few questions.
-
- Most prominent in
the image is the bright equatorial ring of ionized gas. This ring was ejected
from the star for thousands of years before it exploded. It’s now heated by
shockwaves from the supernova. The equatorial ring girdles the hourglass shape
of the fainter outer rights that stem from the polar regions of the star.
-
- These structures
have been observed before by telescopes such as Hubble and Spitzer. But JWST’s
real power is to peer into the center of SN 1987a. There it reveals a turbulent
keyhole structure where clumps of gas expand into space. Rich chemical interactions
have begun to occur in this region.
-
- Even JWST wasn’t
able to observe the ultimate jewel of the supernova, the remnant star.
Supernovae not only cast off new material into interstellar space, they also
trigger the collapse of the star’s core to become a neutron star or black hole.
- Based on the scale
of SN 1987a, a neutron star should have formed in its center. However, the gas
and dust of the inner keyhole region are too dense for JWST to observe it. How
a neutron star forms, and how it interacts with surrounding gas and dust, is a
mystery that will require further study. We have observed the neutron stars of
some supernovae, but only from a much greater distance.
-
- Tycho’s supernova
was just 8,000 light-years from Earth, and Kepler’s about 20,000 light-years
distant. Unless Betelgeuse happens to explode in the near future, SN 1987a is
likely the closest new supernova we’ll be able to study for quite some time.
-
-
December 20, 2023
CLOSEST
SUPOERNOVA 4283
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Thursday, December 21, 2023 ---------------------------------
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