MACS J1149.5+2223
Δημοσιεύτηκε στις 16 Δεκ 2015
Many
stars end their lives with a with a bang, but only a few of these
stellar explosions have been caught in the act. When they are, spotting
them successfully has been down to pure luck — until now. On 11 December
2015 astronomers not only imaged a supernova in action, but saw it when
and where they had predicted it would be. The supernova, nicknamed
Refsdal, has been spotted in the galaxy cluster MACS J1149.5+2223. While
the light from the cluster has taken about five billion years to reach
us, the supernova itself exploded much earlier, nearly 10 billion years
ago. Refsdal’s story began in November 2014 when scientists spotted four
separate images of the supernova in a rare arrangement known as an
Einstein Cross around a galaxy within MACS J1149.5+2223. The cosmic
optical illusion was due to the mass of a single galaxy within the
cluster warping and magnifying the light from the distant stellar
explosion in a process known as gravitational lensing. These multiple
images of the galaxy presented a rare opportunity. As the matter in the
cluster — both dark and visible — is distributed unevenly, the light
creating each of these images takes a different path with a different
length. Therefore the images of the host galaxy of the supernova are
visible at different times. Using other lensed galaxies within the
cluster and combining them with the discovery of the Einstein Cross
event in 2014, astronomers were able to make precise predictions for the
reappearance of the supernova. Their calculations also indicated that
the supernova appeared once before in a third image of the host galaxy
in 1998 — an event not observed by any telescope. To make these
predictions they had to use some very sophisticated modelling
techniques. Since the end of October 2015 Hubble has been periodically
peering at MACS J1149.5+2223, hoping to observe the unique rerun of the
distant explosion and prove the models correct. On 11 December Refsdal
finally made its predicted, but nonetheless showstopping, reappearance.
The detection of Refsdal’s reappearance served as a unique opportunity
for astronomers to test their models of how mass — especially that of
mysterious dark matter — is distributed within this galaxy cluster.
Astronomers are now eager to see what other surprises the ongoing Hubble
Frontier Fields programme will bring to light.
stars end their lives with a with a bang, but only a few of these
stellar explosions have been caught in the act. When they are, spotting
them successfully has been down to pure luck — until now. On 11 December
2015 astronomers not only imaged a supernova in action, but saw it when
and where they had predicted it would be. The supernova, nicknamed
Refsdal, has been spotted in the galaxy cluster MACS J1149.5+2223. While
the light from the cluster has taken about five billion years to reach
us, the supernova itself exploded much earlier, nearly 10 billion years
ago. Refsdal’s story began in November 2014 when scientists spotted four
separate images of the supernova in a rare arrangement known as an
Einstein Cross around a galaxy within MACS J1149.5+2223. The cosmic
optical illusion was due to the mass of a single galaxy within the
cluster warping and magnifying the light from the distant stellar
explosion in a process known as gravitational lensing. These multiple
images of the galaxy presented a rare opportunity. As the matter in the
cluster — both dark and visible — is distributed unevenly, the light
creating each of these images takes a different path with a different
length. Therefore the images of the host galaxy of the supernova are
visible at different times. Using other lensed galaxies within the
cluster and combining them with the discovery of the Einstein Cross
event in 2014, astronomers were able to make precise predictions for the
reappearance of the supernova. Their calculations also indicated that
the supernova appeared once before in a third image of the host galaxy
in 1998 — an event not observed by any telescope. To make these
predictions they had to use some very sophisticated modelling
techniques. Since the end of October 2015 Hubble has been periodically
peering at MACS J1149.5+2223, hoping to observe the unique rerun of the
distant explosion and prove the models correct. On 11 December Refsdal
finally made its predicted, but nonetheless showstopping, reappearance.
The detection of Refsdal’s reappearance served as a unique opportunity
for astronomers to test their models of how mass — especially that of
mysterious dark matter — is distributed within this galaxy cluster.
Astronomers are now eager to see what other surprises the ongoing Hubble
Frontier Fields programme will bring to light.
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