Posted on 09/01/2023 11:04:44 AM PDT by MtnClimber
Explanation: In 1716, English astronomer Edmond Halley noted, "This is but a little Patch, but it shows itself to the naked Eye, when the Sky is serene and the Moon absent." Of course, M13 is now less modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Sharp telescopic views like this one reveal the spectacular cluster's hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter. Approaching the cluster core, upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. The remarkable range of brightness recorded in this image follows stars into the dense cluster core.
For more detail go to the link and click on the image for a high definition image. You can then move the magnifying glass cursor then click to zoom in and click again to zoom out. When zoomed in you can scan by moving the side bars on the bottom and right side of the image.
Really cool to see in a big Dobsonian.
The Great Goo-Goo Cluster....................
😂😂😂😂😂
All those stars/galaxies are receding, going away from us.
False!
M13 is 22,200–25,000 light-years away from Earth, and the globular cluster is one of over one hundred that orbit the center of the Milky Way.
-Wikipedia
Aside from the fact that this cluster is locked in orbit around the center of our galaxy, it is also far too near to us for Hubble Expansion to be a factor. (Hubble Expansion is significant only for distances on the order of tens of millions of light-years.)
Regards,
In physics, the longer the wave length the redder it becomes, the shorter the wave length the bluer it come.
I don't use Wikipedia for knowledge or information.
These are well-established facts which should be known to anyone who has taken high school physics, so I don't understand why you are repeating them (to me).
The fact stands that the Globular Cluster in Hercules is far too close to us - actually still within our own galaxy - for Hubble's Law to be applicable to them. Your initial observation - that "all those stars" in the Cluster were receding from us - was thus incorrect.
I don't use Wikipedia for knowledge or information.
Your prerogative. I could, of course, have instead quoted these facts from memory, or I could have transcribed a passage from my old high school physics textbook - but I thought that it would be more convincing and accessible if I cited a generally-available source like Wikipedia. When the question at hand doesn't concern, e.g., Global Warming, Wikipedia is a quick way to establish basic science facts.
Regards,
But thanks.
I still don't trust Wikipedia though.
Regards, J
When dealing with cosmological distances there are two competing forces at large: gravity and expansion. Gravity gets weaker with distance while expansion gets stronger. At some point, maybe around 25 or 50 million lightyears (depending on the local density), dominance switches from gravity to expansion, so that galaxy groups and clusters tend to remain bound while galactic superclusters get torn apart.
Still skeptical of my statements?
[...] I was just offering up like basic astro stuff [...]
There rapidly comes a point, when you're simplifying stuff, that you start distorting and falsifying it.
[...] not really about the cluster.
In your post #8, you had claimed, "All those stars/galaxies are receding, going away from us." That was in reference to the main article and image, I assumed. But the Hercules Globular Cluster is most certainly not receding from us. Nor are any of a number of galaxies - some millions of light years away - belonging to our Local Group.
For what it's worth:
The Hubble constant is most frequently quoted in (km/s)/Mpc, thus giving the speed in km/s of a galaxy 1 megaparsec (3.09×1019 km) away, and its value is about 70 (km/s)/Mpc.
Mentioning the expansion of the Universe and the Hubble Shift in the context of an article about the Hercules Globular Cluster is like pointing to the corner drugstore and proclaiming, "You know, because of Continental Drift, that drugstore is receding from us!"
Regards,
"Expansion" is not actually a "force."
It would be better to say that there were two factors involved.
And to clarify: The accepted theory is now that the Universe is expanding both because of the residual momentum of the "Big Bang" and the inflation of Space, itself.
Hope that I haven't mangled things all too badly by formulating it so simply.
Regards,
By the way, I like your tag line. It reminds me of someone...
Yes, and I decry the fact that today - in our post-Newtonian world of Physics - you are right! /humor
Why don't you try on a tag-line for size?
Regards,
-0-
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