Why does this Nebula Have Two Lobes?

I am always fascinated by the diversity of colours, shapes, and scenarios that pop up throughout our universe.  Even though we can classify things into categories like ‘planetary nebula,’ ‘galaxy,’ ‘dwarf star,’ and such, there is still a huge amount of variability among these categories.  The most diverse group may be nebulae, since their shape relies on what elements are present, the environment in which they formed, and how far along they are in their evolution.  A great example of a strange and interesting nebula is the PN M2-9, the Twin Jet Nebula.

Hubble image of the Twin Jet Nebula. Image credit: NASA / ESA / Hubble / Judy Schmidt.

Lying 5,560 light years away, in the constellation Ophiuchus, it clearly has two visible lobes of material jetting out from the centre.  Planetary nebulae result from the death of a star with similar mass to our Sun.  In the case of the Twin Jet nebula, the streams are being produced by two stars forming a binary system.  One of the stars is an evolved white dwarf, while the other is a sun-like star at the end of its life, spewing out material.

The shape of the wings is likely due to the motion of the stars around each other and how they interact gravitationally. There is still some debate as to whether all bipolar nebulae are caused by a double star system, but the Twin Jet nebula certainly is, and it is still expanding.

Calculations show that the nebula formed only about 1200 years ago, which is not long at all in astronomical terms, especially when the two stars take 100 years to orbit each other. The orbit also allows the white dwarf to accrete material from the larger star, which forms a huge disk around the pair that extends far from the stars.  If the white dwarf continues to absorb material from the other star, it will eventually reach the 1.4 solar mass limit and explode as a supernova.

The galaxy has some pretty amazing hidden treasures.

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