I agree with Chemahkuu that it's probably Romulus (it might be a Hobus-system planet flashback, but that seems less likely) and probably Vulcan.
And a side-noteto M'Sharak for scaling-down large images and linking rather than just replacing them with text links. More time-consuming, but that's some damn fine moderating!
I'd like to think its the star we're seeing in the back ground since it does look like the surface of an expanding star rather than the shockwave its supposed to be. And it would explain the absense of Remus.
But it would be a waste of time and CGI to show some unimportant system and there are large cities visible on the surface. So this is more than likely Romulus, creating a real damned headache as to where her sister planet has gone.