A galaxy and all its stars

[wimvb]

This galaxy is as faint as it gets. UMa I dSph is a dwarf spheroidal galaxy to the Milky Way. It was discovered as late as 2005, mainly because it is the third dimmest galaxy known (after UMa II Dwarf and Boötes Dwarf galaxies, discovered in 2006). The galaxy is only a few thousand light years in diameter, yet it spans about 20 arc minutes of the night sky, which makes it quite large compared to other galaxies (comparable in angular size to M 81).

Capture details:

Telescope/Camera: SkyWatcher 190MN with ZWO ASI294MM

Exposures: 3 x 60 x 240 s; total exposure time: 12 hours

Processed in PixInsight

Can't see it?

That's probably because at a distance of 330 000 light-years, we can image the individual stars of this galaxy. Here's an annotated version with the brightest stars marked. Each cross is a star.

[wimvb]

I also collected 3 hours luminance, but because of poor guiding I decided not to include it in the image. Still, by inverting and superstretching, it does show the 48 identified stars in this galaxy.

[symmetal]

Wow, that's really faint for 12 hours of data. You certainly need the annotations to pick the stars out out. Challenge accepted. On the list of things to do. 😊

Just posted my Regulus Dwarf image too.

Alan

[GalaxyGael]

Very nice Wim. I have a soft spot for dwarf galaxies and curious/funny to be talking about (just) the 48 stars identified in the galaxy. There are usually more people on a bus . That one looks very faint. Leo II looks interesting too.

[wimvb]

1 hour ago, GalaxyGael said:

Very nice Wim. I have a soft spot for dwarf galaxies and curious/funny to be talking about (just) the 48 stars identified in the galaxy. There are usually more people on a bus . That one looks very faint. Leo II looks interesting too.

Thanks. The galaxy has many more stars, of course. Otherwise it would be an open cluster. It's just that they are so faint that they haven't been uniquely identified yet.

[gorann]

Interesting Wim! For a resident of that dwarf galaxy, what would the Milky Way look like?

[wimvb]

24 minutes ago, gorann said:

Interesting Wim! For a resident of that dwarf galaxy, what would the Milky Way look like?

”In your face”. At 330 000 ly distant and with a diameter of 100 000 ly, the Milky Way would occupy about 15-20 degrees of the night sky in one direction. The concept of Galaxy season would have a completely different meaning.