APOD: The Mermaid Nebula Supernova Remnant (2024 Sep 18)

[APOD Robot]

The Mermaid Nebula Supernova Remnant

Explanation: New stars are born from the remnants of dead stars. The gaseous remnant of the gravitational collapse and subsequent death of a very massive star in our Milky Way created the G296.5+10.0 supernova remnant, of which the featured Mermaid Nebula is part. Also known as the Betta Fish Nebula, the Mermaid Nebula makes up part of an unusual subclass of supernova remnants that are two-sided and nearly circular. Originally discovered in X-rays, the filamentary nebula is a frequently studied source also in radio and gamma-ray light. The blue color visible here originates from doubly ionized oxygen (OIII), while the deep red is emitted by hydrogen gas. The nebula's mermaid-like shape has proven to be useful for measurements of the interstellar magnetic field.

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[AVAO]

The Mermaid Nebula Supernova Remnant

Explanation: New stars are born from the remnants of dead stars. The gaseous remnant of the gravitational collapse and subsequent death of a very massive star in our Milky Way created the G296.5+10.0 supernova remnant, of which the featured Mermaid Nebula is part. Also known as the Betta Fish Nebula, the Mermaid Nebula makes up part of an unusual subclass of supernova remnants that are two-sided and nearly circular. Originally discovered in X-rays, the filamentary nebula is a frequently studied source also in radio and gamma-ray light. The blue color visible here originates from doubly ionized oxygen (OIII), while the deep red is emitted by hydrogen gas. The nebula's mermaid-like shape has proven to be useful for measurements of the interstellar magnetic field.

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This Day in APOD

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The APOD is a great SNR image... even if it is mirrored
Most of the SNR can only be seen in the X-ray.

The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).

Click to view full size image

jac berne (flickr) eROSITA, XXM-Newton and more

[Ann]

Yes, I can see the mermaid!

The Mermaid Nebula Supernova Remnant. Image Credit & Copyright: Neil Corke; Text: Natalia Lewandowska (SUNY Oswego)

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APOD Robot wrote:

(T)he Mermaid Nebula makes up part of an unusual subclass of supernova remnants that are two-sided and nearly circular.

Like the Veil Nebula, you mean?

The Betta Fish Nebula. The Mermaid Nebula is at right. Credit: Marco Lorenzi.

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The Veil Nebula complex. Credit: Achint Thomas.

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Both the Betta Fish Nebula and the Veil Nebula are blue-green from OIII emission and red from Hydrogen alpha. The difference is that the Betta Fish (and Mermaid Nabula) is almost all blue-green, whereas the Veil Nebula contains a lot of red Hα.

There is a lot of red hydrogen in the Veil Nebula. Credit: Trevor Jones.

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A tentative guess on my part is that the Betta Fish Nebula may be older, and the lightweight hydrogen may have dispersed before the oxygen did. Of course it's also possible that the supernova progenitor that created the Betta Fish and Mermaid Nebula was in itself pretty hydrogen-poor, more so than the progenitor that created the Veil Nebula.

And I must say that the eastern Veil Nebula is the only nebula in the sky that gives me the creeps! It's the Grinning Joker Nebula!

The Eastern Veil Nebula. Credit: Achint Thomas.

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The Grinning Joker Nebula. Credit: Brian Ventrudo.

Oh shudder!!! We need to call Batman and Robin!!

No, boys, you are not wanted back on Earth, you are wanted in constellation Cygnus to fight the evil Joker Nebula!

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Ann

[VictorBorun]

The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).

Click to view full size image

jac berne (flickr) eROSITA, XXM-Newton and more

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s

How come?

[Chris Peterson]

The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).

Click to view full size image

jac berne (flickr) eROSITA, XXM-Newton and more

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?

What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.

[VictorBorun]

The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).

Click to view full size image

jac berne (flickr) eROSITA, XXM-Newton and more

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?

What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.

I mean why the range is so wide? can the shock front be so slow?

As for the speed of light I just used kilo light years of distance and kilo years of age which made me use c factor

then again
angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s
I think at as slow mean speed as 24 km/s and probably just 10 km/s currently the shock wave still totally ionizes its oxygen and all

[Chris Peterson]

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?

What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.

I mean why the range is so wide? can the shock front be so slow?

As for the speed of light I just used kilo light years of distance and kilo years of age which made me use c factor

then again
angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s
I think at as slow mean speed as 24 km/s and probably just 10 km/s currently the shock wave still totally ionizes its oxygen and all

I think it's very difficult to confidently assess the distance of an object like this. A very recent paper (see the discussion in section 4) estimates a distance of 1.4 kpc and an age of 14 kyr.

[VictorBorun]

the link won't open

[johnnydeep]

the link won't open

Try this one: https://inspirehep.net/literature/2765684 (I googled for the pdf from Chris' link, which was "stad3921.pdf")

[VictorBorun]

thanks!