Starship Asterisk*

Boomer12k wrote: Are those BRIGHT spots around the red star forming regions 3 o'clock, and 8 o'clock star clusters? Globular Clusters? are they IN M77???

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They are certainly in M77, and I'd say that some of them are clusters. Many of them are probably individual stars. There are no globular clusters in this part of M77, since all the bright points of light here are young stars or clusters. Extremely rich young clusters are called populous clusters or blue populous clusters. The chemical composition of these young clusters is so different from the chemical composition of true globulars (which are rarely less than ten billion years old) that the young clusters are not called "globulars". In any case, the young clusters are very rarely as star-rich as true globulars. A Milky Way populous blue cluster is NGC 3603.

If you take a look at the the region around 8 o'clock in the APOD of M77, you can see that there are very many bright points of light there, but there is not much red nebulosity. I'd say that this part of M77 is a mostly spent region of star formation. There was a huge reservoir of gas here, but now most of it has either been converted into stars, or blown away by stellar winds and possible supernovae. There is a particularly bright point of light there, which is likely a large, bright cluster. Most of the other points of lights may well be individual stars.

Ann

Borc wrote:

isoparix wrote:"At that estimated distance, the gorgeous island universe is about 100 thousand light-years across." Does it have a different width at some other distance....?

Sorta.
We measured how wide it looks to us from our solar system then measured the distance from us to it. Those two numbers can give us the gals diameter, but change the distance and the size would need to change to match in order to maintain the laws of geometry.
The ACTUAL size wouldn't change, just our measurement would (presumably) get better.


If I'm unclear holler, ill be more particular.

I doubt that the Laws of Geometry need maintenance - they need to be obeyed! I think you're being rather casual with your use of the word 'size'.... If you change the distance, the apparent angular diameter changes. The absolute diameter does not change - and it's the absolute diameter that you are quoting.

isoparix wrote:I doubt that the Laws of Geometry need maintenance - they need to be obeyed! I think you're being rather casual with your use of the word 'size'.... If you change the distance, the apparent angular diameter changes. The absolute diameter does not change - and it's the absolute diameter that you are quoting.

The problem is that the distance is not known with certainty, but the angular diameter is fixed. As estimates of the distance change, so will the estimates of the absolute diameter.