Why we can’t see Galactic Center
In summer if you go to a dark place at night and see the sky you realize that you see Galactic Center. You will see a beautiful band of stars. This is actually our on galaxy (Milky Way). Our sun and earth are in a way it’s citizens and there are approximately 200 billion other stars included in the Galaxy.
If you see to watch the constellation Sagittarius in that direction lies the center of our galaxy. We cannot see that center in visible light because there are many dust and gas clouds between us and the center, which obscure our view. If you see the Milky Way at night you realize there are some spaces where you don’t see the stars, the reason is not that there are no stars there rather it is because the dust in blocking our view. Now this view towards the center is beautiful and it seems a calm and beautiful places.
But recently a new study has been published and an extremely beautiful image of the centre has been taken by astronomers through x-ray and radio-waves which tell us that there is extreme chaos and mayhem towards the centre of our own galaxy.
Our Solar System is not in Galactic Center
You know that we live in a spiral galaxy, which is called Milky Way galaxy. A few centuries before humans thought they were at the center of the universe. Leave aside the center of the universe today we know that even our sun is not in the center of our galaxy. Rather, our sun and our solar system are about 26,000 light years from the center of the galaxy. And all the action is the center of the galaxy, and we live far away in a silent neighborhood.
Now there is a supermassive Black hole in the center of all the bigger galaxies. Similarly, there is a supermassive Black hole at the center of our own Milky Way galaxy. If you want to know more on the subject there are some articles on Black hole and on article specifically on the Milky Way Black hole. Kindly check them out.
But today, I want to highlight a new study, published, along with splendid image of the central part of the galaxy (about 1000 light years wide) in x-ray and radio wavelengths. Before I talk about that, let me find out that the author of the study is Professor Daniel Wang who is an astronomer at the University of Massachusetts Amherst and a part of the five college Astronomy Department of which hemisphere college is also a part.
Discuss About Image of Our Galactic Center
Today let’s talk about this awesome image, and what does it tell us about our galaxy.
The picture you are seeing now is a picture of the center region of galaxy. The width of this image is 1000 light years, and the length is 2000 light years. Imagine looking at the Sagittarius constellation and filing that area, which 50 full moons that is the area being filled by this image. But this is not a picture of visible light – visible light is the one which our eyes detect directly. This is a picture of X-ray wavelength taken by the Chandra Space Telescope.
This telescope is named after the great Indian American astronomers Subrahmanyan Chadrasekhar. Who made a lot of discoveries about stellar structure and stellar evolution and who received a Nobel Prize in 1983.
Let’s come back to that image again
This particular image is a composite of 370 images.
What we are seeing now are mostly hot gases as seen in the x-rays. If you want to really understand something in astronomy, it is necessity to study, not only the visible light, but also lights in different wavelengths. So that we know what type of mechanism is producing this.
Now there different colored orange green and purple represent their different energies of x-rays.
This is another image of the same area, but in radio waves.
You are seeing a wispy type structure and the radio waves are tracing magnetic fields in this gas. If you want to be specific and have some knowledge of physics, this night is the one being given by electrons when they are moving around a strong magnetic field. And this light is called “Synchrotron radiation”.
And these magnetic field (astronomers think) are responsible for heating up the gases emitted index in the x-rays.
Now, let’s combine these two images and see.
Wow! Now you know how and which area are emitting both x-rays and radio waves. And in a way, you come to know about the relationship between the two in a beautiful way.
Come, let’s identify some features to understand the image.
- That supermassive Black hole in the center of our galaxy, is already marked towards SGR A* (Sagittarius A*).
- Besides, there are some star clusters such as Quintuplet Cluster and Arches Cluster here. Astronomers suspect that this gas was heated up by the supernova explosions or from the new style clusters or by the heating up of the material near the supermassive Black hole.
Now I want to draw your attention towards specific features.
This is an unusual thing that these threads have been specially studied in the study.
Remember, this is not visible light, but you are seeing the gas in x-ray and radio waves.
Why is this thread so slim?
Astronomers thinks that the gas here is highly collimated because of the magnetic fields.
What is the exact reason?
We don’t know, but some people think that the gas clouds, present near the center of our galaxy, then they collide with one another (they also have magnetic fields), some magnetic fields disconnect and then reconnect again. This is also called “Magnetic Reconnection”.
Process of Galactic Center
We know somewhat about this, because this process also taken place in our sun. The solar wind from our sun is produced because of this process. Meaning that magnetic field of the Sun pushes out some charged particles into our solar system. These particles also impact the Earth, this is called solar wind. And if there are a large number of particle, it is called a solar storm.
Puzzle
Now there is this puzzle: how is the gas near the center of our galaxy getting heated so much? The process (some people think) is because of the magnetic field of these streamers.
Back to first image
Apart from this. Astronomers have also discovered large-scale plumes of hot gas in this image which are present 700 light years above and below the plane of our galaxy. These plumes are easily visible in radio waves. It is assumed that just as our sun makes the outflowing solar wind, the gas plumes (near the center of a galaxy) are the same phenomena on a large scale.
But what is heating up this gas?
It is again suspected that it is heated up because of the supernova or star clusters or the supermassive black holes of our galaxy. But these gas plumes have magnetic fields within them. And when these gas clouds collide with other gas clouds, it results in these streamers.
The streamers(not one, but several) are mostly perpendicular to the Galaxy.
Now, after all this, you can see that that the activity in the central region of over galaxy is due to many reasons. And there is no need to blame our poor supermassive Black Hole.
Occasionally I am asked if the supermassive Black hole at the center is gobbling up our galaxy? No, it is very small in size relative to the scale of the galaxy. So you can see a lot of activity taking place, and a supermassive Black hole in the center of our galaxy , relatively small part in it.
Leave all these technical things aside you go out at night in summer and look towards the Milky Way specially towards the direction of the constellation Sagittarius. And imagine what great activity is taking place behind the stars and dust clouds in the central region of out galaxy. There we have streamers, gas plumes, supernovae and star clusters and supermassive Black hole heating up this gas which we can see in x-ray and radio waves and result in this absolutely beautiful picture of it.
