Globular Clusters: The Cosmic Rebels
In the early days of this galaxy’s birth, did you know that the Milky Way was likely more spherical in shape? Not like the 2 dimensional disks in which we marvel through telescopes and pictures, but rather 3 dimensional spheroids that mimic the much larger elliptical galaxies we see in places like Virgo’s Markarian Chain. You know, the boring looking ones.
No, our beautiful galaxy, which we reckon would look a lot like the neighboring Andromeda Galaxy, wasn’t always a grand spiral with spinning arms spreading out like a whirlpool. Today, if we could view it from the side, it would most certainly look like the thin silvers of NGC4565, NGC 891, or the famous M104 Sombrero. However, billions of years ago, the Milky’s Way side would have looked much like it’s front, with nothing to hint at the spinning arms of a galactic grand spiral that we love today.
So, how do galaxies like ours decide that they don’t wish to be a big M87-like elliptical forever?
In space, everything pulls on everything. Closer to the beginning of our universe, clumps of space stuff glommed together, like oil beading up in water. And within these clumps, matter is gravitationally pulled towards other matter, stars clustering with stars, planets catching a ride with a neighboring star and hanging on for what will seem like an eternity.
But in space, this cosmic dance of zillions of tons of space stuff will spin. Gravity just works that way. It has to. And the more mass something has, the more likely that it will spin…faster and faster. This is true of everything: dirt sticking together to form a spinning planet, hydrogen and helium becoming a spinning sun, and solar system objects caught up together within their orbits.
And when a much larger spheroid shaped mass of space stuff, now called a galaxy, has enough radial velocity and enormous amounts of moderately massive material, all this stuff will also spin together and begin to radiate outward, flattening itself into a disk, a really big and really pretty disk.
But interestingly, not everything heeds the galaxy’s spin. Some of the stuff is too massive or too far away to be sucked into the newly spinning arms. Perhaps in fact, the earliest of the galaxy’s stars, who found other 1st generation stars to spend their lives with, united against the centrifugal forces now taking in all the lighter gases, dust, and stars that were scattered much nearer the galactic center.
Instead, these “globs” of stars, now numbering together in the thousands, have enough pull of their own to resist a move into the galaxy’s arms and remain on the same path they’ve always traveled.
These globs of stars, known today as globular clusters, wandering their own paths around the galactic halo, have persisted all these eons of time. Over 150 such globulars are known in the Milky Way galaxy, many of which reside further away from the galactic center than our own solar system does. Thus, if you think that the galactic “halo” extends only to the top of the “sombrero,” then you are likely mistaken. Although much of the galactic mass is bound together in the spinning arms, the dimensions of the galaxy are still very much elliptical, a testimony to those old clusters of stars that bucked the odds, or just decided together that they didn’t need galaxy arms to be pretty.
In fact, through a telescope, globular clusters are not just pretty. They are gorgeous! Often looking like powdered sugar against the blackness of space, they are an explosion of tens of thousands of stars, concealing well their total numbers.
The stars within globular clusters look old, mostly red giants in their later stage of existence. Together, they represented the first of the galaxy’s stars to band together in order to form enough gravitational-bound mass to rebel against the establishment. Left in a community of kinship for billions of years, stars spend their live-cycles, die their spectacular deaths, and scatter there remaining mass, soon to find partnership with other “space stuff“ that met the same fate. Now reborn to become part of another generation of stars and given the same fate of their much older neighbors, they too will spend a seeming eternity well away from the spinning arms of the newly formed grand spiral galaxy.
“Hell, no, we won’t go,” the juvenile stars cry!
They make their neighbors proud.
No, our beautiful galaxy, which we reckon would look a lot like the neighboring Andromeda Galaxy, wasn’t always a grand spiral with spinning arms spreading out like a whirlpool. Today, if we could view it from the side, it would most certainly look like the thin silvers of NGC4565, NGC 891, or the famous M104 Sombrero. However, billions of years ago, the Milky’s Way side would have looked much like it’s front, with nothing to hint at the spinning arms of a galactic grand spiral that we love today.
So, how do galaxies like ours decide that they don’t wish to be a big M87-like elliptical forever?
In space, everything pulls on everything. Closer to the beginning of our universe, clumps of space stuff glommed together, like oil beading up in water. And within these clumps, matter is gravitationally pulled towards other matter, stars clustering with stars, planets catching a ride with a neighboring star and hanging on for what will seem like an eternity.
But in space, this cosmic dance of zillions of tons of space stuff will spin. Gravity just works that way. It has to. And the more mass something has, the more likely that it will spin…faster and faster. This is true of everything: dirt sticking together to form a spinning planet, hydrogen and helium becoming a spinning sun, and solar system objects caught up together within their orbits.
And when a much larger spheroid shaped mass of space stuff, now called a galaxy, has enough radial velocity and enormous amounts of moderately massive material, all this stuff will also spin together and begin to radiate outward, flattening itself into a disk, a really big and really pretty disk.
But interestingly, not everything heeds the galaxy’s spin. Some of the stuff is too massive or too far away to be sucked into the newly spinning arms. Perhaps in fact, the earliest of the galaxy’s stars, who found other 1st generation stars to spend their lives with, united against the centrifugal forces now taking in all the lighter gases, dust, and stars that were scattered much nearer the galactic center.
Instead, these “globs” of stars, now numbering together in the thousands, have enough pull of their own to resist a move into the galaxy’s arms and remain on the same path they’ve always traveled.
These globs of stars, known today as globular clusters, wandering their own paths around the galactic halo, have persisted all these eons of time. Over 150 such globulars are known in the Milky Way galaxy, many of which reside further away from the galactic center than our own solar system does. Thus, if you think that the galactic “halo” extends only to the top of the “sombrero,” then you are likely mistaken. Although much of the galactic mass is bound together in the spinning arms, the dimensions of the galaxy are still very much elliptical, a testimony to those old clusters of stars that bucked the odds, or just decided together that they didn’t need galaxy arms to be pretty.
In fact, through a telescope, globular clusters are not just pretty. They are gorgeous! Often looking like powdered sugar against the blackness of space, they are an explosion of tens of thousands of stars, concealing well their total numbers.
The stars within globular clusters look old, mostly red giants in their later stage of existence. Together, they represented the first of the galaxy’s stars to band together in order to form enough gravitational-bound mass to rebel against the establishment. Left in a community of kinship for billions of years, stars spend their live-cycles, die their spectacular deaths, and scatter there remaining mass, soon to find partnership with other “space stuff“ that met the same fate. Now reborn to become part of another generation of stars and given the same fate of their much older neighbors, they too will spend a seeming eternity well away from the spinning arms of the newly formed grand spiral galaxy.
“Hell, no, we won’t go,” the juvenile stars cry!
They make their neighbors proud.
