The center of the Milky Way is 26,000 light years from Earth. Literally almost a journey distance from here in a spaceship traveling at a speed of... 99.9999999999999 percent of the speed of light.
The center of the Milky Way is 26,000 light years from Earth. Literally almost a journey distance from here in a spaceship traveling at a speed of... 99.9999999999999 percent of the speed of light. On the other hand, there are astrophysicists such as UCLA astrophysicist Prof. Andrea Gaz, who know this center intimately, as if they visited it only yesterday. Since the mid-XNUMXs Gaz has been measuring the motion of the stars in the heart of our galaxy. She has gathered evidence that puts together a puzzle that a supermassive black hole resides right at the center of the Milky Way (see the TED video below).
This black hole appears to have a mass that is over three million times the mass of our Sun. What is a supermassive black hole? Black holes are exotic objects in space. A black hole is an object in space that swallows a huge amount of mass into zero volume. Because of this, the understanding of the center of the black hole - called a singularity - is beyond the scope of the astrophysicist's ability. And that's why John Weiler said the famous sentence "Black holes don't have hair". Astrophysical holes are determined by their valence, charge, and angular momentum. Everything else is "hairs" that disappear behind the event horizon, and therefore cannot be observed.
Physicists are trying to combine quantum mechanics - which describes how the tiny world works - with general relativity - which describes our understanding of the vast world of gravity - all in order to understand what is happening in the heart of the black hole.
The hunt for the black hole at the center of the Milky Way
In fact, about 30 years ago, scientists began to think about the possibility that black holes might exist in unusual galaxies with active nuclei, that is, those whose center is active. They therefore began to examine the possibility that there might be a supermassive black hole in the center of those galaxies, one that fuels the unusual activity of their center. Maybe what we're actually seeing is nothing more than matter falling straight into these giant monsters at the center of these active galaxies? The scientists asked themselves: do these black holes have a huge feast fueling them?
From this the astrophysicists deduced that there may be other black holes in other galaxies. It turned out that probably at the center of all galaxies, ordinary galaxies, resides a supermassive black hole. These thoughts led astrophysicists to think that probably in our galaxy - for the milky way - a super massive black hole resides.
In the XNUMXs, the first hint of the appearance of higher mass concentrations in the center of our galaxy appeared. At first, of course, the phenomenon could be explained by assuming the normal concentration of stars and gas around the center of our galaxy. Observations have not yet condensed the normal mass into a volume small enough to demonstrate the existence of a black hole at the center of the galaxy. Because of this, some scientists have suggested that perhaps at the center of the galaxy resides a collection of things that do not shine. For example, dead stars. This was certainly a reasonable possibility in view of the experiments carried out at the time. Hints still remain that the observations could still be better explained by the supermassive black hole model at the center of the galaxy. But the evidence was not enough for this scenario.
How could they finally prove the existence of a supermassive black hole at the center of the Milky Way? The key to the proof lay in demonstrating an enormous amount of mass in a tiny volume. The demonstration was performed with the help of the movement of the stars. The way the stars move around the center of the galaxy is largely the same as the way the planets move around the sun. That is, basically it is Kepler's laws. They use a model of the movement of the planets around the sun and the way the mass of the sun is measured. In exactly the same way, the movement of the stars that rotate around the center of the galaxy is measured and from here they try to measure what is the mass inside their inner orbit. To do this, the innermost stars around the center of the galaxy must be measured in order to show that there is a lot of mass in a very small volume. This is the key to proving a supermassive black hole.
The first intuitive thought that comes to mind, as we think of a supermassive black hole, is that such a black has a super-strong gravitational pull. Hence, why wouldn't it suck the entire Milky Way and perhaps our distant Earth as well? As far as we know, at least from our experience in our tiny little corner, this apocalyptic scenario is not happening. Most of the objects near the supermassive black hole revolve around it and are not sucked into it. The reason is the enormous speed - about twenty percent of that of light - at which they move. They fall around and not into the super massive hole. They must be very close to the black hole or its event horizon to be sucked in and become a tasty meal for it. In fact they should be at a distance that is closer than the distance between the Earth and the Sun. To the extent that; And for this reason the stars, which are indeed close to the supermassive hole, revolve around the hole peacefully and undisturbed until they fade, just as the sun will revolve around the center of the galaxy throughout its life.
How to watch the center of the galaxy?
The problem that remains, then, is how to observe the stars - called S - that are located very close to the center of the galaxy? With which astronomical instrument will they be observed? Of course, with the help of a normal technique, they cannot be seen nor can they be measured because the Earth's atmosphere limits the measurements. How to overcome this limitation? First, it can be done by the Hubble telescope, which is outside the atmosphere in space. Second, telescopes can be used on Earth and have the ability to penetrate through the atmosphere. A special telescope and special techniques are needed. Andrea Gaz and her team from California used the Keck telescope, the largest telescope in the world on Earth - a telescope more sophisticated than the Hubble telescope. Although it is not located above the atmosphere, its diameter is four times larger than Hubble, which means that you can see four times more detail than you can see in Hubble. All this if you know how to use the technique and penetrate through the atmosphere.
Gaz began measurements in 1995 and the first hint was received in 1997. Gaz observed in 2003 the first star to orbit as if it were being pulled around by a supermassive black hole at the center, instead of only moving half an orbit around. The same star, which astrophysicists have noticed since 1995, is called S2. This star is called a star of spectral type B and it is an extremely hot and very bright star and its color is blue. Since the Keck telescope began observing the S2 star, it has managed to rotate the supermassive black hole for 15.9 years along a complete orbit.
The supermassive black hole and the small star around it
A researcher from Italy examined the super massive hole located in the center of our Milky Way galaxy in the radio source Sagittarius A* and the star S2. You don't need a telescope, but mathematical calculations and analysis of the disturbances. It turns out that the supermassive black hole and the stars around it are an ideal local laboratory, which can be a test for the theory of general relativity.
The dynamics of the orbit of the star S2 should be very different from Kepler's well-known third law - Kepler's famous ellipse - and Newton's law of gravity. The study initially examines a Schwarzschild-type black hole as well as a cold, rotating black hole. And there are other factors, which we will not go into.
The supermassive black hole induces two types of gravito-electromagnetic perturbations (GEM) on the environment of the S2 star: the largest perturbation is gravitoelectric perturbation (GE) which is responsible for the anomaly of Mercury's perihelion moving at 43.98 arcsec in the Sun's gravitational field. And the second, smaller disturbance, the gravitomagnetic (GM) - the Lance-Thiring effect (discovered in 1918). A black hole rotates, changing the space-time around it - and slightly the direction of the rotation axis of the star S2.
Given these two disturbances, the result obtained from the calculations is that an anomaly should be expected in the orbit of S2, and it is three orders of magnitude greater than the anomaly seen in the orbit of the planet Hema (Mercury). Both in the case of Mercury and in the case of the star S2 the effects of these anomalies are predicted by Einstein's theory of general relativity. These effects can be explained as a result of the space-time curvature both in the vicinity of the supermassive black hole in the center of the galaxy, in the case of the star S2, and also in the vicinity of the sun, in the case of the star Hema.
For news on the subject in Universe Today
For the TED video of researcher Amdrea Gaz about the search for the supermassive black hole
28 תגובות
Does anyone know Dr. Zvi Shalom Grank?
The correspondence is fun and so is the article - even if it may be lacking, in the opinion of tassel testers - the question is anyway - why tinker with the tip of iodine? It's good that it was written and it's good that the talented writer in the XNUMXth century wrote it, of course
Crescent moon:
http://en.wikipedia.org/wiki/Galaxy_formation_and_evolution
http://en.wikipedia.org/wiki/Spiral_galaxy
Sahar Shalom.
A short Google search would answer your question.
The article is very interesting.
I have a question and I think I know the answer but I'm not sure so I'll ask,
The shape of spiral galaxies (the spirals :D) result from the invention of a black hole in their center?
deer:
For some reason I didn't notice your comment until now.
The video I was talking about is the TED video linked at the end of this article.
I enjoyed reading the article and I was happy about the link to the attached video, thank you Gali and happy new year to you.
Excellent article.
The subject of the black hole at the center of the galaxy is not clear enough.
According to Wikipedia (http://en.wikipedia.org/wiki/Sagittarius_A*) There are two different barriers to the mass (I am not mistaken, they are achieved by two different techniques).
In general, if Galli was relying on a paper from several years ago, it is quite possible that she ran into the 3 million solar mass number as the error rates were larger and indeed included that estimate as well.
As for Michael's question about the orbit of the second star.
I don't know where the video you took is from, so I can't examine what you're saying (what do you mean by cutting the two tracks?). The correct thing as far as I understand is to place an upper limit on the radius of the dark mass in the form of the perihelion of the orbit closest to the black hole.
If the topic interests you, in 2005 a professor from the Weizmann Institute (Tal Alexander) wrote a fairly comprehensive review on the topic of the environment of the center of the galaxy in which references to everything mentioned here appear - search:
Stellar processes near the massive black hole in the galactic center
Tal Alexander
(arXiv:astro-ph/0508106)
There is something in Guy's words.
indeed,
Writing skills in K. and links in K.
The intention is clear
writing skills in
Avi,
This is of course up to you, but from the material I came across it lacks the appropriate links for writing on the site. The most disturbing thing about her writing is that she pretends to explain subjects she does not understand so that it is difficult to make a diagnosis in which areas she is "really" strong
Anonymous user, the information you entered is correct and accurate.
Now my lovers who sign here with pointless jokes like A. Ben Ner are asked to go and sing poison songs under the balcony of women writers on other sites.
The author of the article received her Ph.D. from the Hebrew University in 2000 in the field of history of sciences. The doctoral thesis focused on Henri Poincaré's contribution to Einstein's special theory of relativity, and was written under the guidance of the late Prof. Mara Beller.
to love
Unfortunately, I also share your feelings, as you expressed them in your responses below (number: 3 6 8 and 12).
I take my hat off to you for your restraint.
To (Dr.?) Gali Weinstein
I admit that I doubt your sincerity, but of course I cannot prove my skepticism.
At the same time, for the avoidance of doubt, and the aforementioned doubt exists, I am turning to you, please refer the
Site readers to your academic resume page, if it exists somewhere.
Maybe you could refer us to your doctoral thesis, which as far as I remember you claimed in your resume that you deleted it
About Albert Einstein.
As you remember, you hastily deleted your resume from your website a few months back
that questions were asked and doubts were raised about the truth and reliability of the details written there.
Instead of your academic résumé, a cute picture of a cute girl with a flower appears on the website
Habib with Albert Einstein. Yes, he also looks very nice there.
My dear Habib, Habib Habib - this is not a substitute for a real and factual resume and the questions asked.
Your refusal to answer these questions for so long only increases the suspicions.
And the sooner the better.
Of course, if it turns out that I was wrong in my suspicions of you, I will be the first to respond here and apologize to you.
Gali (Dr. Grenk) and to think that I dared to doubt your abilities. You were a professor's wife just one rank below the desired title - an engineer's wife.
jelly:
For many years during my career I have been involved in software.
They say that a plan goes to sleep with one full glass and one empty glass next to it.
The full glass is there in case he wakes up in the middle of the night and is thirsty.
The empty cup is there in case he wakes up in the middle of the night and is not thirsty.
I say this because your answer - although it gave the final conclusion, presented only part of the explanation for not knowing him and left me out. If you wouldn't explain - I wouldn't ask - but if you change a certain explanation - questions like - maybe he is a relative of your husband and the like are asked.
And to your question: Yair Grenk is indeed a very nice person. really! And yes, he is also CEO and owner of a company, but that is less important in my opinion.
Michael,
I don't know Yair Granak but it would be nice if I knew him because he is CEO and it sounds good to work in his company.
My name is Gali Weinstein Grenk. I was married to Grenk, but he is a professor at Ben Gurion and not the owner and CEO of any company. Too bad right?
jelly:
Do you happen to be in touch with Yair Granak - the owner and CEO of BizDevUSA?
jelly,
Genius also rhymes with balloon. This does not mean that there is a connection between them, one of them is just puffy.
Especially for you I will sign my name: Dr. Gali Granek
Then you can put together a list of doctors that contains the names: Dr. Avital and Dr. Grenk. And this is in order not to insult Einstein who thinks that Weinstein rhymes with Einstein. 🙂
jelly
I thought you were an expert in the field? Suddenly it turns out that "I took the material in the article from several sources". As usual there are no quotes as usual everything is attributed to you and as usual full of errors. I am sorry in many ways that you claim to represent scientists and science.
Michael
It is also possible to compile a list of doctors containing the names: Dr. Gabi Avital and Dr. Gali Weinstein. I wonder what they have in common?
Ehud and A. Ben Ner I missed you both or Ehud Ben Ner. They already sing me songs here.
to Michael Very true and that is indeed what I wrote. John Weiler said black holes don't have hairs exactly because of what you said and that's what I wrote in my paper and that's what should appear there. In the original article by the researcher from Italy, he takes this into account, so I added it. Although it does not appear in the news from Universe Today, it does appear in a technical article by the researcher from Italy.
You may be right. I took the material in the article from several sources and not just from the news in Universe Today, as you can see. I took this from an interview with Andrea Gaz. And I don't remember where it was published. If I had remembered then I would have brought the link. Try to search for the interview conducted with Andrea Gaz and you can get the link. There is all the information. And it will also help the readers to know the source of the article.
Gali, Gali, why did you laugh?
when you took the teddy bear
And did you put him to sleep?
why did you laugh
Did he tell you something funny?
on a ticking clock
Tick and tick
A bag veteran?
Come on Gali,
come wave to me
Where does the sweet laugh come from?
Come on Gali,
come wave to me
I still want to laugh too.
wavy, wavy
Why did you ask what happened and why?
Is it already night and not day?
why did you ask
Do you remember how the curtain
With the sun he danced all day, all day at the window
Come on Gali,
come wave to me
How did you remember the light?
Come on Gali,
come wave to me
I also still want to remember.
wavy, wavy
Why did you cry when it first rained?
Knocked on the window?
why did you cry
Did he tell you something terrible?
About a wet cat
that got wet and cost him
the heat?
Come on Gali,
come wave to me
Where do the tears come from?
Come on Gali
come wave to me
I still want to cry too.
Beat the expert.
wavy ????
jelly:
John Weiler said black holes have no gate - not because of the singularity but because the only properties black holes outwardly exhibit are mass, charge, and angular momentum.
http://en.wikipedia.org/wiki/Black_Hole_No_Hair_Theorem
The "hairs" he was referring to are a metaphor for additional features that usually characterize the rest of the bodies we know (well - of course he also meant a crude joke - but it was still accepted on the humanities and the joke is suppressed).
In the news in Universe Today it is written that the mass of the black hole is estimated at four million solar masses. Does the three million come from another source?
I remember that many years ago I read that they came to the conclusion about the existence of a black hole at the center of the galaxy thanks to the (partial) orbit of a star that approaches the center and as if literally jumps back in a very close orbit.
I think you see this star also in the video she shows (minute 10:45) - its orbit is depicted in yellow.
She says in the video that the volume into which they managed to delimit these 4 million solar masses is greater than the volume dictated by the Schwarzschild radius, so the proof has not yet been won - only that it is very likely.
I ask myself why she is only looking at the trajectory of S2 and not at the intersection between this trajectory and the trajectory I talked about earlier. I think it would have reduced the volume enough.
This may be due to the fact that we only see the two-dimensional projection of the orbit, which may be tilted, but I don't think this is the case because the orbits of all the stars are drawn there as if looking over the galaxy, which indicates that they were able to extract the inclination of their orbit from the available data (such as the Doppler effect ).
Excellent article.
Thanks