A Neutron Star Rests at Supernova 1987A’s Center

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A Neutron Star Rests at Supernova 1987A’s Center

Post by Ann » Thu Feb 22, 2024 7:42 pm

A Neutron Star Rests at Supernova 1987A’s Center

https://www.discovermagazine.com/the-sc ... 7as-center

The James Webb Space Telescope (JWST) first imaged Supernova 1987A (SN) in September 2022. The image captured a mysterious dusty and gassy center that formed during the supernova’s explosion. The dust is so thick it shrouds near-infrared light. But, within the dusty center, a powerful hot neutron star may be lurking underneath, according to a new study published in Science.
“It was so exciting looking at the JWST observations of SN 1987A for the first time. As we checked the MIRI and NIRSpec data, the very bright emission from argon at the center of SN 1987A jumped out. We knew immediately that this was something special that could finally answer the question on the nature of the compact object,” said Patrick Kavanagh, the study's co-author and an astrophysicist at Maynooth University, in a press release.
...
Using the JWST’s MIRI and NIRSpec instruments, scientists found that the argon and sulfur atoms around the area where the supernova occurred were ionized. Only an event like a neutron star that blasted the particles with ultraviolet or X-ray radiation could have ionized the atoms. Strong cosmic winds from a rotating neutron star mixing with the supernova’s material could also have caused this.

In their study, the authors note that what ionized the atoms could have been a neutron star in one of two scenarios. It may have been the radiation emanating from the blazing, million-degree heat from the new star or from particles that accelerated in the supernova’s magnetic field as the neutron star rapidly spun. Models agree with both neutron star options. But which one is more challenging to pinpoint? More observations with JWST and on-the-ground telescopes may help the team glean more information.

Either way, both options fit with the team’s speculations of a neutron star residing in the center of SN 1987A.
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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by AVAO » Fri Feb 23, 2024 7:12 pm

Ann wrote: Thu Feb 22, 2024 7:42 pm A Neutron Star Rests at Supernova 1987A’s Center

https://www.discovermagazine.com/the-sc ... 7as-center

The James Webb Space Telescope (JWST) first imaged Supernova 1987A (SN) in September 2022. The image captured a mysterious dusty and gassy center that formed during the supernova’s explosion. The dust is so thick it shrouds near-infrared light. But, within the dusty center, a powerful hot neutron star may be lurking underneath, according to a new study published in Science.
“It was so exciting looking at the JWST observations of SN 1987A for the first time. As we checked the MIRI and NIRSpec data, the very bright emission from argon at the center of SN 1987A jumped out. We knew immediately that this was something special that could finally answer the question on the nature of the compact object,” said Patrick Kavanagh, the study's co-author and an astrophysicist at Maynooth University, in a press release.
...
Using the JWST’s MIRI and NIRSpec instruments, scientists found that the argon and sulfur atoms around the area where the supernova occurred were ionized. Only an event like a neutron star that blasted the particles with ultraviolet or X-ray radiation could have ionized the atoms. Strong cosmic winds from a rotating neutron star mixing with the supernova’s material could also have caused this.

In their study, the authors note that what ionized the atoms could have been a neutron star in one of two scenarios. It may have been the radiation emanating from the blazing, million-degree heat from the new star or from particles that accelerated in the supernova’s magnetic field as the neutron star rapidly spun. Models agree with both neutron star options. But which one is more challenging to pinpoint? More observations with JWST and on-the-ground telescopes may help the team glean more information.

Either way, both options fit with the team’s speculations of a neutron star residing in the center of SN 1987A.
ThanX Ann

The study is very exciting.

What still irritates me is the fact that the two outer rings (outlines) already existed before the breakout 1987,
which to me indicates cyclical breakouts.


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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by Ann » Sat Feb 24, 2024 6:28 am

AVAO wrote: Fri Feb 23, 2024 7:12 pm
The study is very exciting.

What still irritates me is the fact that the two outer rings (outlines) already existed before the breakout 1987,
which to me indicates cyclical breakouts.

Thanks for your fantastic images, Jac! I absolutely agree that Sanduleak −69° 202, the supernova progenitor, must have undergone cyclical outbursts. The reason why the outer outlines "from the star to the supernova remnant" are completely unchanged can only mean, the way I understand it, that the explosive debris from the supernova has not yet reached "the outer limits" of the previously deposited material.

There is one more reason why we should absolutely assume that Sanduleak −69° 202 had lost mass before, and that is that it exploded as a blue supergiant. It may possible (I think!!!) that stars can explode as blue supergiants without going through the red supergiant stage. That would require, I think, that the core is so unstable that it collapses before it manages to make its outer layers expand enormously and cool prodigiously. Don't know if it is possible.

What is definitely possible for massive stars is to undergo episodes of great mass loss. Just consider Eta Carina!


As for Sanduleak −69° 202, it exploded, as I said, as a blue supergiant. To me, that strongly suggests that the star had shed much (if not most) of is outer layers to change itself from a huge red supergiant into a smallish blue supergiant. If it shed its outer layers in a violent but non-destructive explosion, it may have become a supernova impostor prior to exploding as a supernova for real.

Wikipedia wrote:

Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and giant eruptions of luminous blue variables (LBV).

Supernova impostors appear as remarkably faint supernovae of spectral type IIn—which have hydrogen in their spectrum and narrow spectral lines that indicate relatively low gas speeds. These impostors exceed their pre-outburst states by several magnitudes, with typical peak absolute visual magnitudes of −11 to −14, making these outbursts as bright as the most luminous stars. The trigger mechanism of these outbursts remains unexplained, though it is thought to be caused by violating the classical Eddington luminosity limit, initiating severe mass loss. If the ratio of radiated energy to kinetic energy is near unity, as in Eta Carinae, then we might expect an ejected mass of about 0.16 solar masses.

It is not certain that Sanduleak −69° 202 has ever been a supernova impostor. But in my opinion, it is indeed highly likely that this star has shed so much mass that it turned itself into a blue instead of a red supergiant. And as I said, the debris from the supernova has not yet caught up with the matter that was shed by Sanduleak −69° 202 before it went supernova.

The Astrophysics Spectator wrote:

SN 1987A is classified as an unusual type II supernova. It is type II because it has hydrogen lines in its spectrum. It is unusual because the doppler shift of those lines suggests an expansion of around one-tenth the speed of light (twice the expansion speed of a typical type II supernova) and because it is much less luminous than a typical type II supernova, although the total amount of energy released in the explosion is similar to that released in a typical type II supernova. SN 1987A is also unusual in brightening in only 3 hours, rather than over the several days that is more typical of type II supernovae. These unusual features are directly tied to the small radius of the exploding star. The rapid brightening of the star directly reflects this small radius; more time is required for the energy released by the collapse of a star's core to travel to the photosphere of a red supergiant than to that of a blue supergiant, because the red supergiant is physically much larger than the blue supergiant. The remaining-two characteristics?the high velocity and the low luminosity?are set by the star's radius through the thermodynamics of a supernova.

Sanduleak −69° 202 was a blue supergiant because it had shed so much of its outer layers from when it was a red supergiant. The cast-off layers still form the outer outline of the pre-supernova Sanduleak −69° 202 as well as of SN 1987A!

At least that's my take on it!

Ann
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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by AVAO » Mon Feb 26, 2024 5:51 pm

Ann wrote: Sat Feb 24, 2024 6:28 am
Thanks for your fantastic images, Jac! I absolutely agree that Sanduleak −69° 202, the supernova progenitor, must have undergone cyclical outbursts. The reason why the outer outlines "from the star to the supernova remnant" are completely unchanged can only mean, the way I understand it, that the explosive debris from the supernova has not yet reached "the outer limits" of the previously deposited material.

There is one more reason why we should absolutely assume that Sanduleak −69° 202 had lost mass before, and that is that it exploded as a blue supergiant. It may possible (I think!!!) that stars can explode as blue supergiants without going through the red supergiant stage. That would require, I think, that the core is so unstable that it collapses before it manages to make its outer layers expand enormously and cool prodigiously. Don't know if it is possible.

What is definitely possible for massive stars is to undergo episodes of great mass loss. Just consider Eta Carina!


As for Sanduleak −69° 202, it exploded, as I said, as a blue supergiant. To me, that strongly suggests that the star had shed much (if not most) of is outer layers to change itself from a huge red supergiant into a smallish blue supergiant. If it shed its outer layers in a violent but non-destructive explosion, it may have become a supernova impostor prior to exploding as a supernova for real.

Wikipedia wrote:

Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and giant eruptions of luminous blue variables (LBV).

Supernova impostors appear as remarkably faint supernovae of spectral type IIn—which have hydrogen in their spectrum and narrow spectral lines that indicate relatively low gas speeds. These impostors exceed their pre-outburst states by several magnitudes, with typical peak absolute visual magnitudes of −11 to −14, making these outbursts as bright as the most luminous stars. The trigger mechanism of these outbursts remains unexplained, though it is thought to be caused by violating the classical Eddington luminosity limit, initiating severe mass loss. If the ratio of radiated energy to kinetic energy is near unity, as in Eta Carinae, then we might expect an ejected mass of about 0.16 solar masses.

It is not certain that Sanduleak −69° 202 has ever been a supernova impostor. But in my opinion, it is indeed highly likely that this star has shed so much mass that it turned itself into a blue instead of a red supergiant. And as I said, the debris from the supernova has not yet caught up with the matter that was shed by Sanduleak −69° 202 before it went supernova.

The Astrophysics Spectator wrote:

SN 1987A is classified as an unusual type II supernova. It is type II because it has hydrogen lines in its spectrum. It is unusual because the doppler shift of those lines suggests an expansion of around one-tenth the speed of light (twice the expansion speed of a typical type II supernova) and because it is much less luminous than a typical type II supernova, although the total amount of energy released in the explosion is similar to that released in a typical type II supernova. SN 1987A is also unusual in brightening in only 3 hours, rather than over the several days that is more typical of type II supernovae. These unusual features are directly tied to the small radius of the exploding star. The rapid brightening of the star directly reflects this small radius; more time is required for the energy released by the collapse of a star's core to travel to the photosphere of a red supergiant than to that of a blue supergiant, because the red supergiant is physically much larger than the blue supergiant. The remaining-two characteristics?the high velocity and the low luminosity?are set by the star's radius through the thermodynamics of a supernova.

Sanduleak −69° 202 was a blue supergiant because it had shed so much of its outer layers from when it was a red supergiant. The cast-off layers still form the outer outline of the pre-supernova Sanduleak −69° 202 as well as of SN 1987A!

At least that's my take on it!

Ann
ThanX Ann

There you made some good points there. It will be exciting to see what future research on this object will reveal as the fog surrounding the central object slowly clears. I think the study above is just a first step and will not be the only one.

I like SN 1987A also as WEBBLE ;-)

Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
jac berne (flickr)

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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by Ann » Mon Feb 26, 2024 6:30 pm

AVAO wrote: Mon Feb 26, 2024 5:51 pm ThanX Ann

There you made some good points there. It will be exciting to see what future research on this object will reveal as the fog surrounding the central object slowly clears. I think the study above is just a first step and will not be the only one.

I like SN 1987A also as WEBBLE ;-)

Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
jac berne (flickr)
Great images as usual, Jac! And in both the Hubble and the Webb closeups, there is a tiny bright object at the center of the nebula!

Ann
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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by AVAO » Tue Feb 27, 2024 5:12 am

Ann wrote: Mon Feb 26, 2024 6:30 pm
AVAO wrote: Mon Feb 26, 2024 5:51 pm ThanX Ann

There you made some good points there. It will be exciting to see what future research on this object will reveal as the fog surrounding the central object slowly clears. I think the study above is just a first step and will not be the only one.

I like SN 1987A also as WEBBLE ;-)

Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
jac berne (flickr)
Great images as usual, Jac! And in both the Hubble and the Webb closeups, there is a tiny bright object at the center of the nebula!

Ann
Sorry no. That was the goal of my research. In the MIRI images from JWST, no object was visible in the center anywhere, which surprised me. The dot in the middle just shows where it should be, and the white circle shows that there is nothing there.This means that if it has something in the middle, then that something does not glow in the higher mid-infrared.

But in the new released argon-related pictures from JWST it is.
Strange ...
Image credit: NASA / ESA / CSA / STScI / C. Fransson, Stockholm University / M. Matsuura, Cardiff University / M.J. Barlow, University College London / P.J. Kavanagh, Maynooth University / J. Larsson, KTH Royal Institute of Technology.

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Re: A Neutron Star Rests at Supernova 1987A’s Center

Post by Ann » Tue Feb 27, 2024 10:52 am

AVAO wrote: Tue Feb 27, 2024 5:12 am
Ann wrote: Mon Feb 26, 2024 6:30 pm
AVAO wrote: Mon Feb 26, 2024 5:51 pm ThanX Ann

There you made some good points there. It will be exciting to see what future research on this object will reveal as the fog surrounding the central object slowly clears. I think the study above is just a first step and will not be the only one.

I like SN 1987A also as WEBBLE ;-)

Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
Click to view full size image 1 or image 2
jac berne (flickr)
Great images as usual, Jac! And in both the Hubble and the Webb closeups, there is a tiny bright object at the center of the nebula!

Ann
Sorry no. That was the goal of my research. In the MIRI images from JWST, no object was visible in the center anywhere, which surprised me. The dot in the middle just shows where it should be, and the white circle shows that there is nothing there.This means that if it has something in the middle, then that something does not glow in the higher mid-infrared.

But in the new released argon-related pictures from JWST it is.
Strange ...
Image credit: NASA / ESA / CSA / STScI / C. Fransson, Stockholm University / M. Matsuura, Cardiff University / M.J. Barlow, University College London / P.J. Kavanagh, Maynooth University / J. Larsson, KTH Royal Institute of Technology.
That's so strange, Jac. The fact that Hubble can't detect a dust-enshrouded neutron star at the center of the SN1987A remnant - if there is a dust-enshrouded neutron star at the center of the SN1987A remnant - is not strange, in view of Hubble's limited infrared capabilities.

But the fact that Webb can't detect an infrared signal from such an object is just completely baffling.

As you say, though, the argon signal detected by Webb apparently more or less proves that a neutron star is there.

Ann
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