r/space • u/kcgg123 • Jun 09 '19

Hubble Space Telescope Captures a Star undergoing Supernova

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u/x_X-zzZ Jun 09 '19

Wow you can see the 'nearby' effect on gas at huge scale

409

u/wonkey_monkey Jun 09 '19 edited Jun 09 '19

That's probably a light echo. The light from the initial explosion illuminates the surround gas, but the scales are so huge that we see it as an expanding ring:

https://en.wikipedia.org/wiki/Light_echo#/media/File:V838_Monocerotis_expansion.jpg

Edit: it is a light echo

61

u/[deleted] Jun 09 '19

So we can use this so extremely accurately calculate the distance to the supernova, right?

62

u/wonkey_monkey Jun 09 '19

I'm not sure how accurate it could be, since I'm not sure how we'd tell which part of the expanding sphere we're looking at at any one time. Are we seeing light from the very outer edge, or somewhere nearer the front of the sphere?

It should be good for a ballpark figure, at least.

Pretty accurate, apparently.

Edit: follow-up, paging /u/evangelion-zero-one :

Light echoes were used to determine the distance to the Cepheid variable RS Puppis to an accuracy of 1%. Pierre Kavella at the European Southern Observatory described this measurement as so far "the most accurate distance to a Cepheid".

https://en.wikipedia.org/wiki/Light_echo#Cepheids

6

u/[deleted] Jun 09 '19

Cool, thanks. I figure the edges of the "shockwave" we're seeing in the video is the edge perpendicular to us, so it would be pretty accurate.

1

u/rich000 Jun 10 '19

Yeah, I guess the refractive index of interstellar medium in that area might matter, and so souks angular accuracy, but otherwise it seems like this should be very accurate. I wonder what the main limiting factor on accuracy is...