The stars in small globular galaxies behave in a way that has led scientists to speculate that their mass is mainly dominated by dark matter. This is what researchers from the University of Michigan claim
The stars in small globular galaxies behave in a way that has led scientists to speculate that their mass is mainly dominated by dark matter. This is what researchers from the University of Michigan claim. Professor of Astronomy, Mario Mathieu, and postdoctoral researcher Mathieu Walker measured the speed of 6,804 stars in seven satellite galaxies surrounding the Milky Way - Carina, Draco, Furnax, Leo 1, Leo 2, Sculptor and Scutanes. They found that, contrary to what was expected from the predictions made according to Newton's laws, the stars in these galaxies do not move more slowly the farther they are from the center of the galaxy.
"In these galaxies we see the problem straight from the nucleus" says Matteo. "The speed of the stars is not small. She just stays the same, and that's the strangest thing.
Astronomers already know that stars in spiral galaxies behave in a similar way. This research has recently dramatically increased the information available about the smaller galaxies and made possible the ability to confirm that the distribution of light and stars in them is not the same as the distribution of mass.
"We have more than doubled the amount of data we had on these galaxies, and this allows us to study them in an unprecedented way. Our studies have shown that dwarf galaxies are completely dominated by dark matter," says Walker. Walker received his doctorate from the University of Michigan earlier this year and is now completing a postdoctoral fellowship at the University of Cambridge in the UK.
Dark matter is an entity that astronomers have not been able to observe directly, but they infer its existence because they can detect its gravitational effect on visible matter. Based on these measurements, the current prevailing theory in astronomy and cosmology is that the visible parts of the universe constitute only a fraction of all matter and energy.
"The planet Neptune was once 'dark matter'," said Mathieu. Before the term was even coined, astronomers predicted its existence based on an anomaly in the orbit of its neighbor in the solar system - Uranus. They knew exactly where to look for Neptune
For the last quarter of a century, astronomers have been searching for the Neptune of the universe, if you can call it that. Dark matter can take the form of dwarf stars and planets, elementary particles including neutrinos, or as yet undiscovered hypothetical particles that do not interact with visible light or other parts of the electromagnetic spectrum.
Dark matter is what scientists say holds the galaxies together. The gravitational force of the visible matter is not strong enough to prevent the stars from escaping the galaxy. Other theories have arisen to try to explain this discrepancy, such as modified Newtonian dynamics, Mathieu says, which claims that gravitational forces become stronger when acceleration forces are weak. The results are in any way consistent with the predictions of the dark matter model but do not rule out the less popular theory.
These dwarf galaxies are not worth looking at, but this may change after the results of our research and the new insight into the nature of dark matter, and perhaps even gravity.
Walker presented his research at the Magellan Scientific Meeting held on October 30 in Cambridge, Massachusetts. The study was published in the September 20 issue of the Astrophysical Journal Letters.
12 תגובות
Shall we leave it to the students? 🙂
to R. Besha
OK, but these are black guys whose mass density is high, so I know that their relativistic behavior is significantly different from the Newtonian one.
But is the difference significant also in very large but not dense masses?, I don't see it.
Sabdarmish Yehuda
Yehuda Sabdarmish
I'm not sure that it is not so much triggered by the mass, for example when there is a binary system of black holes or neutron stars, the gravitational waves cause a loss of energy, and the system will collapse - good for the prediction of Newton's laws. But again, I'm really not an expert.
to R. Besha
General and special relativity is affected by the speed of the masses and their density, I am not sure also by the size of the masses.
As far as I know, a large and slow galaxy should behave according to Newton in a very precise way.
But I will use the weekend to test
Sabdarmish Yehuda
Yehuda Sabdarmish
I wasn't talking about special relativity - I meant general relativity. It deviates from Newton's laws not only because of the speeds of the objects, but just because of the enormity and the enormous distances.
(But I'm not an expert, so it's very possible that I'm wrong, and that the results are not so affected by the relative correction on such a scale)
per person
You can get an exhaustive explanation by reading my articles:-
On spiral galaxies, gravitation and dark mass
You can find the article on Google if you search for the above name
In general, I show a possibility that maybe the pressure differences between particles in space will be enough to move the galaxies, without the need for gravity.
Sabdarmish Yehuda
Yehuda Sabdarmish
Your claim is that the range of influence of gravity has a finite size?
And can this explain the phenomenon of the movement of the stars as described in the article?
You also do not lack Yehudah, keep standing up. 🙂
When I said empty, of course I didn't mean empty that the questioner was wondering about, and in the same line I wrote the Higgs field... so please don't be a bother and try to understand.
Lami Bachar, like you, I also believe that the entire universe is full of countless particles and is far from empty.
I just think what would have happened if I had approached the distinguished researchers and told them that in my opinion not only is there no dark mass, there is also no gravitation at galactic distances. They would look at me like a creature from another world, or someone who escaped from some kind of closed institution,
To R. Besha. I agree with you that Newton's formulas that are proven with a high degree of accuracy only at small distances of our solar system are not suitable for use also for galactic complexes because of their uncertainties.
There is also no need to use the formulas of the theory of relativity because of the small speed of the galaxies and the stars in them, relative to the speed of light.
Have a good day
Sabdarmish Yehuda
post Scriptum. I pay attention to the hours you responded, I understand that when I have insomnia there is nothing better than browsing the science website. With a smile!
Newton's laws? How do you expect normal results if you use Newton's laws on the order of galaxies?
Is there a blank?
Either these are black holes or these are macroscopic effects of the Higgs field in the vacuum. And in general, it seems to me that in the end it will turn out that there is no difference between these two.