2006-09-25 13:38:35 · 13 answers · asked by Brianna Fool:) 2 in Science & Mathematics ➔ Astronomy & Space
Interesting question. There was an excellent article about this in a recent edition of Astronomy a few months back.
It turns out that just about every galaxy that has been tested for a black hole does indeed have one. Astronomers can tell by measuring the velocity of stars as they orbit the black hole, just like planets orbit a star. The current understanding suggests that billions of years ago, when most galaxies were first forming, super-massive stars that were very close together started collapsing, forming black holes of hundreds of solar masses. From there gas flowed in at an enormous rate, feeding the black hole. A massive rotating disc of gas formed around the growing galactic black hole, and from that disc the gas grew hotter and hotter as it orbited the black hole. Just as the super-hot gas entered the event horizon and disappeared forever, two massive jets spewed EM radiation from the magnetic N and S poles for hundreds of thousands of light years. Astronomers now think these are the origins of Quasars.
So eventually all the available gas within the gravitational pull of the now-truly-massive black hole is consumed. Without any additional gas, the jets disappear, all light and radiation from the black hole disc stop, and all you have is the mass of millions, hundreds of millions, even billions of stars. Except for the random star that gets too close, the black hole is essentially dead.
What's truly interesting is that the central galactic black hole has about 1% or so of the total mass of the galaxy. Astronomers now think that the black hole plays a crucial, indispensable role in the formation of the galaxy.
2006-09-25 17:21:32 · answer #1 · answered by ZenPenguin 7 · 3⤊ 1⤋
Spiral galaxies (including ours) do seem to have a black hole at or very near the centre, as evidenced by stellar orbits and light curves. Since elliptical galaxies are thought to be formed by a collision of spirals (our galaxy and Andromeda are due for just such a collision in a few billion years), there would have to be one there as well. Certainly, elliptical galaxies appear to have far more mass than they should (again judging by stellar orbits), so presumably the black holes in the spirals merge into one when the elliptical galaxy is formed.
2006-09-25 14:16:30 · answer #2 · answered by stevewbcanada 6 · 2⤊ 0⤋
There are different sized black holes in different galaxies..
Some galaxies may not have a black hole..
The milky way galaxy does indeed have a medium sized
black hole in the center...
2006-09-25 14:32:05 · answer #3 · answered by Anonymous · 1⤊ 0⤋
the super Bang become no longer an explosion. It become a selection of area-time and the splitting of a unmarried stress into 4 regular forces. If the super Bang theory holds real, *each* degree of count resulted from the unique singularity, no longer in easy terms the undertaking discovered interior the theorized black holes interior the middle of galaxies.
2016-10-17 23:33:40 · answer #4 · answered by cardish 4 · 0⤊ 0⤋
Well we can't observe a black hole directly,but we do have evidence that there could be a giant black hole in the center of our galaxy,and some other ones too,but certainly not all galaxies have one.
2006-09-25 15:33:43 · answer #5 · answered by That one guy 6 · 0⤊ 1⤋
Well large can be deceiving. Large in terms of mass: yes. At least in our galaxy or ones like it. Large in terms of volume: no! Even the largest super-massive black holes are only estimated to be about as large as the size of the Earth if you measure their Schwartzchild radius.
Still given their huge mass they affect their entire galaxy causing it to spiral around them in the case of spiral galaxies.
2006-09-25 13:55:38 · answer #6 · answered by midwestbruin 3 · 2⤊ 1⤋
Yes, there is a supermassive black hole at the center of our galaxy. We have no way of knowing whether or not there is one at the center of every galaxy, but many other spiral galaxies have black holes at the center.
2006-09-25 13:43:01 · answer #7 · answered by Anonymous · 2⤊ 3⤋
Yes it's true...Each Galaxy has a Black Hole...
It's also true that each human also has a black hole smack in the middle of the buttock...(nice way of saying A.S.S.)
So explore both to better understand the workings of our Universe...HEHE
2006-09-25 14:48:56 · answer #8 · answered by Anonymous · 0⤊ 2⤋
Yes, most spiral galaxies are whirling around their sync.
2006-09-25 14:01:17 · answer #9 · answered by NaughtyBoy 3 · 0⤊ 1⤋
Hi. Not all. The elliptical galaxies don't seem to have them.
2006-09-25 13:40:51 · answer #10 · answered by Cirric 7 · 1⤊ 3⤋