Image: Hubble sees a youthful cluster

Image: Hubble sees a youthful cluster
Credit: ESA/Hubble & NASA,  Acknowledgement: Judy Schmidt

Shown here in a new image taken with the Advanced Camera for Surveys (ACS) on board the NASA/ESA Hubble Space Telescope is the globular cluster NGC 1783. This is one of the biggest globular clusters in the Large Magellanic Cloud, a satellite galaxy of our own galaxy, the Milky Way, in the southern hemisphere constellation of Dorado.

First observed by John Herschel in 1835, NGC 1783 is nearly 160,000 light-years from Earth, and has a mass around 170,000 times that of the sun.

Globular clusters are dense collections of stars held together by their own gravity, which orbit around galaxies like satellites. The image clearly shows the symmetrical shape of NGC 1783 and the concentration of stars towards the center, both typical features of .

By measuring the color and brightness of individual stars, astronomers can deduce an overall age for a cluster and a picture of its history. NGC 1783 is thought to be less than one and a half billion years old—which is very young for globular clusters, which are typically several billion years old. During that time, it is thought to have undergone at least two periods of star formation, separated by 50 to 100 million years.

This ebb and flow of star-forming activity is an indicator of how much gas is available for star formation at any one time. When the most created in the first burst of formation explode as supernovae they blow away the gas needed to form further stars, but the gas reservoir can later be replenished by less massive stars which last longer and shed their gas less violently. After this gas flows to the dense central regions of the star cluster, a second phase of star formation can take place and once again the short-lived massive stars blow away any leftover gas. This cycle can continue a few times, at which time the remaining gas reservoir is thought to be too small to form any new stars.


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Image: Hubble sees an ancient globular cluster

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Citation: Image: Hubble sees a youthful cluster (2015, August 31) retrieved 26 June 2019 from https://phys.org/news/2015-08-image-hubble-youthful-cluster.html
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Aug 31, 2015
Globular clusters are dense collections of stars held together by their own gravity, which orbit around galaxies like satellites.

Somehow, as a complete novice, I'm somewhat puzzled as to why the cluster doesn't collapse on itself due to this gravity.
astronomers can deduce an overall age for a cluster and a picture of its star formation history.

ebb and flow of star-forming activity

Has anyone ever recorded a star formation to enable us to understand how and when stars actually "form"? Is there any definite and direct observation that is accessible for reference?
If not then how can these statements be made as if Nebular "star formation" is a fact? And even have a "history"? If one doesn't have a history of the creation and development of a particular phenomenon how can one conclusively assign an age to other occurrences?
I find it hard to understand how people can make these statements with such confidence, given the total lack of real observations.


Aug 31, 2015
Somehow, as a complete novice, I'm somewhat puzzled as to why the cluster doesn't collapse on itself due to this gravity.

They are in motion, they are big and the gravity between individual stars is weak over large distances. That makes for sloooow changes.

Even so a gravity 'collapse' doesn't mean that stuff just hits each other. Space is so incredibly large that suns that gravitationally fall towards one another are almost infinitely more likely to miss (fly past and away from each other...to either escape or get turned back eventually to repeat the process again) than to collide.

Note that when the Andomeda galaxy hits ours (in roughly 4 billion years) the chance that our sun will actually hit any star from Andomeda is 1 in 100 billion or thereabouts

Aug 31, 2015
If one doesn't have a history of the creation and development of a particular phenomenon how can one conclusively assign an age to other occurrences?
I find it hard to understand how people can make these statements with such confidence, given the total lack of real observations.


Because modern astronomy is lost in a myriad of conclusions based on Huge Bang Fantasy model. They have it backwards. And in order to be published, astronomers must adhere to the Fantasy model. Otherwise, they have no career. Modern cosmology suffers from extreme merger mania, much like the flat earth mania a few centuries ago.

Aug 31, 2015
@FredJose. This is the actual statement:
By measuring the color and brightness of individual stars, astronomers can deduce an overall age for a cluster and a picture of its star formation history. NGC 1783 is thought to be less than one and a half billion years old...

If things are "deduced" or "thought to be", then they aren't taken as facts but as plausible explanations of phenomena. There are no real-time observations of such events, due to its large scale. Otherwise, there would be no need for investigation. You should focus on astronomers's technics to know how they reached its conclusions.

Aug 31, 2015
Hmmm... Tuxford... if you agree that "having the history" and real time observations are the only way to support "modern astronomy", then you need that to support ANY cosmology model: Including your LaViolette Stuff. Having such evidence for it?

Aug 31, 2015
Hmmm... Tuxford... if you agree that "having the history" and real time observations are the only way to support "modern astronomy", then you need that to support ANY cosmology model: Including your LaViolette Stuff. Having such evidence for it?

Hi Guy,
My point being only that there is heavy institutional bias built into mainstream interpretations. If one does not look for the assumptions from outside the fantasy model, then one will also miss the mark automatically. However, the publication process funnels the interpretations to correlate with already accepted merger model assumptions, which then become unassailable facts. By the time one obtains a phd in the field, likely no amount of insight can overcome the assumptive facts.

Sep 01, 2015
I find it hard to understand how people can make these statements with such confidence

We have pretty good models. We know how stars work (fusion). We know what type of elements are produced at what rate under what conditions. While the simulations for this are pretty complex the actual physical processes are not. And these processes have been experimentally verified so the confidence in them is pretty high.

So from the spectrogram of a star you can see how bright it is and what kinds of elements it contains (and in what amount). From that and the mass of the star you can deduce its age and a bit of its history (e.g. what generation of star it is).
Cosmology isn't guesswork.

(there are other methods, too. See wikipedia)

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