"The group observed the colossal winds of material—or outflows—that originate near the supermassive black hole at the heart of the pair's southern galaxy, and have found the first clear evidence that stars are being born within them."
"These stars are thought to be less than a few tens of millions of years old, and preliminary analysis suggests that they are hotter and brighter than stars formed in less extreme environments such as the galactic disc."
"are travelling at very large velocities away from the galaxy centre"
11 comments
Um, stars being created now doesn't invalidate the Big Bang as the start of the universe...
Nowhere in the Big Bang theory does it say that at that point, EVERYTHING was created and nothing ever changed again. You seem to be getting it mixed up with Genesis.
If it were me, I'd chuck this guy in CSTDT in a heartbeat just for the phrase "counter-intelligence spooks", but regardless.
Stars being formed from existing material is a key component of the cosmology that flows from the Big Bang model (since they aren't held to have been created as stars, and clearly they have to have been formed somehow ). And, while I'm not an astrophysicist, it seems intuitively correct that stars that form in regions of denser material should form (relatively) more rapidly than ones that form in regions of more sparse material; consequently they would burn hotter relative to their age.
Continuous creation, if I understand it right, requires matter to be created ex nihilo during the life of the universe, but this finding doesn't suggest that any more than normal stellar nurseries do. This is the same background material that's always there in star formation, just concentrated by the presence of the aforementioned black hole.
Completely unrelated subjects. Nothing about the expansion of the modern universe from a central point dismisses the prospect of a sustaining force or process feeding new energy into it. That said, nothing about this particular process (that I can see) suggests that the material is coming from nothing. It's kind of a famous trait of black holes that they suck in everything around them down to light, itself, after all. So far as we know, there's nothing suggesting that all the matter they draw in just winks out of existence. Therefore it may simply be that the natural life cycle of a black hole ends with them gorging themselves to the point that rupture & explode into a new star and that's what we're seeing.
Ugh, this nutter needs to leave phys.org alone.
It's kind of a famous trait of black holes that they suck in everything around them down to light, itself, after all.
This isn't really true, but I see where you're coming from because this is the image they have in pop-sci. Black holes are extremely messy eaters and typically just throw things around and tear stuff up. For instance, a proposed explanation for hypervelocity stars is that they result from the interaction of a binary pair of stars and a supermassive black hole. Another example of black holes being messy eaters are relativistic jets :
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Black holes can also happily let things orbit around them without gobbling them up. One good example of this is Sagittarius A* .
image
Therefore it may simply be that the natural life cycle of a black hole ends with them gorging themselves to the point that rupture & explode into a new star and that's what we're seeing.
No, that's not what would happen when a black hole dies. And the universe is far too young for any black holes to have evaporated yet , in about 1043 years the universe will be primarily dominated by black holes (both by ones that currently exist and ones that have formed since now) and they'll only start evaporating around 5.8×1068 years from now.
The primary sources of star formation are the gravitational collapse of nebulae or other regions of dust and gas that are compressed due to pressure waves created from star death or violent events such as galaxy mergers. Some examples:
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@dxdydz
@DarkPhoenix
Lets consider a star cluster and a black hole of the same mass. In the case where we'd want to measure the amount of gravity created by a mass we can use Gauss's law for gravity.
image
Which basically states that if we surround an object with a closed surface then the amount of gravitational force through that surface is constant, and is invariant with respect to the shape of the surface. So here we see that both the star cluster and the black hole have the same amount of gravity. A key difference is the amount of force a mass can experience from the cluster and the black hole:
Newton's shell theorem says that if we pick some radius r which is greater than the radius of the cluster and the black hole then we will feel the same gravitational effect from each one at that distance r. If we had something like a spherical star cluster of 10000 solar masses and radius rsc where stars are evenly distributed within it then the maximum amount of force we'd experience would be Fmax =G×mus ×m10000 /(rsc )2 , as if we went inside the cluster then other stars would be pulling in an opposing direction.
But with a black hole of 10000 solar masses we can get arbitrarily close to the singularity (yes, eventually we would cross the event horizon and have a bad time), so Fmax wouldn't exist as there is no upper bound to the force we'd be able to experience. So is is possible to experience a stronger gravitational force from the black hole than from the cluster.
@dxdydz
Thank you for this very interesting explanation, black holes are absolutely fascinating. I think (and correct me if I'm wrong please) the problem pop-science has is that it implies that gravity always "pulls" objects to its source, while in reality, masses "fall" towards gravitational centers because their movement paths are warped by the curvature of space-time in that region. On Earth, if we want to move in a straight line we are not leaving the planet because our paths are warped towards the Earths mass (unless we move at sufficient speed of course). A black hole is no different, it's just that we can (as you have explained) get "nearer" to the gravitational source (the singularity) since it is extremely compressed. In a hypothetical scenario in which our sun would be magically replaced by a black hole of equal mass, our solar system wouldn't collaps towards it but the planets would remain in their orbits because space-time wouldn't be affected differently from their perspective. The event horizon is the border after which every objects path, no matter how fast, is warped to fall back into the black hole itself (or to put it differently, after which the escape velocity is greater than the speed of light). That includes their paths through time, which means (or at least could be interpreted as) that the singularity becomes the only possible future for these objects. Interestingly, if the black hole is big enough (supermassive like the one that is most likely inside the core of our galaxy) you can actually survive the entry into the event horizon. Since the event horizon is so far outside of the singularity, the tidal forces which normaly create the deadly "spagghettification" effect aren't as strong at the border than they would be at a smaller black holes event horizon. Not that it matters anyway, since you wouldn't be able to escape to tell anyone what it was like inside of it, but it is fascinating nonetheless.
@dxdydz
I just stated that the effect would be stronger at the event horizon of a "smaller" black hole than it would be for a supermassive one. I didn't say anything about spagghettification not happening away from the event horizon.
Thank you for your suggestions, I will look into all of them. :)
@ChrisBP747
Ah, okay. It was this bit that led me to that interpretation of what you wrote:
deadly "spagghettification" effect aren't as strong at the border than they would be at a smaller black holes event horizon.
It's true but for some reason it made me think you were saying that spaghettification only happens at or extremely close to the event horizon; sometimes I read things weird I guess. But thanks for clarifying what you meant.
Confused?
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