I am not sure that it is that remarkable (for this website), given the known faintest Milky Way's satellites are ~ 100 times fainter, and there probably ten-ish galaxies fainter than And XXXV around the MW.
1st 'graph of the related paper explains the significance:
Ultrafaint dwarf galaxies are critical probes of the properties of dark matter and the physical drivers of galaxy formation at very low mass scales. In the roughly two decades since their first discovery, tens of ultrafaint satellite galaxies of the Milky Way have been discovered. As individual systems, they are extremely dark matter dominated and most appear to have primarily early star formation that is impacted strongly by reionization.
To be fair, this is the paper on which the article is presumably based rather than TFA itself, though I (as apparently others) was unable to read the linked source due to the indeed ridiculously stringent CAPTCHA.
Obvious reasons why faint dwarf galaxies proximate to our own home galaxy might be more observable than even those of our nearest (large) galactic neighbour are obvious, and are a trivial tangent not worth elaboration.
I work in this field and written papers on these objects, so I am aware of their significance. This is exactly why I left the comment for people to know whether that's something particularly novel or interesting (for non-experts) or not.
What's notable is less the faintness, and more the distance / proximity.
I don't know that this is the most distant very faint dwarf satellite observed, but it is the faintest orbiting the Andromeda galaxy, to date. That may speak to observations not possible with nearer VFDGs, or speak to new observational methods / techniques / equipment which made the observation possible.
I'd hope that someone working in the field (I do not) might be able to comment more substantively on such matters, rather than quibble over the relatively uninteresting fact that nearer VFDGs have been observed with far lower absolute luminosity, which ... is rather to be expected.
I am not a policeman of what could be submitted,
but some results are remarkable enough/interesting enough because they are record breakers or unusual in one way or another. This is run of the mill galaxy in Andromeda. And because Andromeda is quite far away the faintest galaxies we can detect there are in fact much brighter than what we can detect around the MW.
I guess I'm fundamentally pushing back on the idea that it has to be at the extreme end of a phenomenon to be interesting. I think the phenomenon of tiny satellite galaxies is interesting, full stop. far more remarkable than something being the smallest. Any distribution will have a smallest element, it follows from the distribution existing at all. Similarly, if satellite in orbit of Andromeda I don't see the value of bringing whataboutism into it.
I was just puzzled to see this paper posted, when we have discovered tens of objects like this over last years. Again, no harm done here, really, but I thought the context is useful.
