Source of the supernova remnant must be in here somewhere!

The source of the gas bubble, of which the greenish arc I noticed earlier is a part, is probably somewhere in this field, roughly where the faint distant galaxy is located, at the mid-point between the three stars. It would require a more sensitive image to be able to detect it, I think.

To save you from having to flip back and forth between my posts to see the bubble, here is the enhanced view of it, with the approximate location of the source object circled.

Supernova remnant.jpg

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Looks like this was a few years ago, but in case you didn’t get an answer, this is actually a planetary nebula rather than a supernova remnant. And your culprit is a white dwarf (the blue object in the top right of your first image).

I agree that it is not a supernova remnant - there would be more visible mess left than this if it had been a supernova.

But despite what it says in SIMBAD I don’t think the bright blue star is the source - it is about a full arc minute away from the centre of the bubble. I have measured a new image from the current image data set, and I have confirmed that the centre of the bubble is where I marked it. There is a faint bluish object roughly at the centre of that marker.

If EGB6 is actually the source of the gas bubble, there must be quite a cosmic wind out there blowing it sideways! *

Unfortunately, for some reason the website is not uploading the new image I have processed to show this more clearly. :unamused:

*I suppose another explanation for the source being off-centre could be the movement of the star since it produced the bubble. Is there any data on that? Could it have moved that far?

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Gaia does have proper motion for it (albeit pretty slow) moving to the right. This PN is ancient, so the WD could easily have moved that far in relation to the centre of the PN.


So, if we know the proper motion of the white dwarf from Gaia, we should be able to trace it back to the marked origin of the bubble and work out how long ago the star erupted the shell. I can’t work out the trajectory, but assuming it has moved directly from A to B at its maximum reported proper motion, we can calculate an order of magnitude for the age of the nebula.

My rough guesstimate puts it about 4,000 years ago, based on the reported proper motion of about 15 milliarcseconds a year and the current displacement from the approximate origin of the bubble.

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The gaia astrometry for the WD is suspect (RUWE>2) due to it being an unresolved binary, so I wouldn’t try and do such calculations personally.

Does that change its speed?

It means that there is lower confidence in the astrometric measurements. Proper motion is included in that.

Not sure I understand why that is. The position should not be in any doubt, it’s bright enough.

…but then I see from the paper on Gaia measurements that it’s a very complex statistical process to extract measurements from certain types of object. I don’t understand it myself as I am not a statistician, but I guess I just have to accept the fact.

Unresolved binaries throw it off. It thinks 2 objects are actually 1 and it gets confused.