APOD: SH2-308: The Dolphin Head Nebula (2024 Jun 07)

[Chris Peterson]

An anti-nose or a few ones are needed to conserve the total momentum without an invisible party

What momentum is not being conserved? This isn't a planetary nebula, it is a shock front created by winds coming off a star. Does a CME from the Sun require a matching one from the opposite hemisphere to conserve any momentum?

my guess was that the nose is a dissipating track of massive fast-moving body, something like “Cannonball Pulsar” only of smaller mass and greater size

A "cannonball pulsar" is a star (or stellar remnant) ejected from its original location. All we're seeing in this nebula is a shock front created by stellar winds... and I see no reason to assume it will be perfectly spherical, given that stars can and do throw off particles non-isometrically.

Also, what we're seeing here isn't material from the star, but surrounding material being ionized by particles from the star. So the shape of the nebula is determined in part by the density and density variations of the interstellar medium in that region.

[VictorBorun]

2

What momentum is not being conserved? This isn't a planetary nebula, it is a shock front created by winds coming off a star. Does a CME from the Sun require a matching one from the opposite hemisphere to conserve any momentum?

my guess was that the nose is a dissipating track of massive fast-moving body, something like “Cannonball Pulsar” only of smaller mass and greater size

A "cannonball pulsar" is a star (or stellar remnant) ejected from its original location. All we're seeing in this nebula is a shock front created by stellar winds... and I see no reason to assume it will be perfectly spherical, given that stars can and do throw off particles non-isometrically.

Also, what we're seeing here isn't material from the star, but surrounding material being ionized by particles from the star. So the shape of the nebula is determined in part by the density and density variations of the interstellar medium in that region.

Now I think you might imply something like this:
1) there used to be a triple stellar system, including an invisible red or brown or black dwarf
2) some time before the main star went Wolf-Rayet the dwarf was cannonballed out and a more massive companion was thrown into the main star;
3) then the cannonball dwarf created a track through the interstellar medium and the the main star went Wolf-Rayet;
4) then the Dolphin Head was created and in the place of the cannonball's track the shock wave met rarefied medium and formed the Nose

[Chris Peterson]

2

my guess was that the nose is a dissipating track of massive fast-moving body, something like “Cannonball Pulsar” only of smaller mass and greater size

A "cannonball pulsar" is a star (or stellar remnant) ejected from its original location. All we're seeing in this nebula is a shock front created by stellar winds... and I see no reason to assume it will be perfectly spherical, given that stars can and do throw off particles non-isometrically.

Also, what we're seeing here isn't material from the star, but surrounding material being ionized by particles from the star. So the shape of the nebula is determined in part by the density and density variations of the interstellar medium in that region.

Now I think you might imply something like this:
1) there used to be a triple stellar system, including an invisible red or brown or black dwarf
2) some time before the main star went Wolf-Rayet the dwarf was cannonballed out and a more massive companion was thrown into the main star;
3) then the cannonball dwarf created a track through the interstellar medium and the the main star went Wolf-Rayet;
4) then the Dolphin Head was created and in the place of the cannonball's track the shock wave met rarefied medium and formed the Nose

Seems like a stretch...