[HN Gopher] Black-hole-triggered star formation in the dwarf gal...
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       Black-hole-triggered star formation in the dwarf galaxy Henize 2-10
        
       Author : Brajeshwar
       Score  : 46 points
       Date   : 2022-02-14 17:26 UTC (5 hours ago)
        
 (HTM) web link (www.nature.com)
 (TXT) w3m dump (www.nature.com)
        
       | miika wrote:
       | What goes in must come out. 1st law of common sense LoL
        
       | BiteCode_dev wrote:
       | So... they recycle matters into stars?
       | 
       | Can we say black holes are in fact... green?
        
         | chrsig wrote:
         | I mean, they are the best trash compactors known to us...
        
       | tejtm wrote:
       | previous thread https://news.ycombinator.com/item?id=30027502
        
       | eminence32 wrote:
       | > Black-hole-driven outflows ... probably play a role in heating
       | and expelling gas (thereby suppressing star formation)
       | 
       | I feel like there is a neat science-fiction story in here
       | somewhere :) A hyper-advanced space civilization embarks on a
       | multi-million-year mission to tow black holes into neighboring
       | galaxies in order to suppress star formation there and thus
       | reduce the chances of competing civilization appearing in the
       | next few billion years
        
         | cgriswald wrote:
         | My first question would be why such a civilization isn't just
         | colonizing that galaxy. If the reason is that those distances
         | are too hard to cross, then my question is why they're
         | concerned about other civilizations developing. Of the top of
         | my head, the best reason they would be worried about it is
         | because it is something they would do themselves; but ever for
         | an advanced civilization that seems like an expensive project
         | with limited return. Or maybe they're as fearful as Larry
         | Niven's puppeteers.
         | 
         | It also would be more efficient to go to that galaxy, tow its
         | stars around, and form new black holes there. You'd move much
         | less mass a much shorter distance. You could probably even pick
         | a relative handful of stars and just nudge them and wait;
         | they're already moving after all. Might as well use that
         | momentum.
        
           | echelon wrote:
           | > My first question would be why such a civilization isn't
           | just colonizing that galaxy.
           | 
           | Super advanced AI civilization spreads in all directions.
           | Eventually the loyalty and purpose bits flip and the far-
           | flung frontiers no longer share the same mission profile or
           | allegiances.
        
           | withinboredom wrote:
           | Maybe they can't colonize it due to multi-year gestation
           | periods? Thus they can't grow the population fast enough.
        
             | kadoban wrote:
             | Maybe any civilization it can create there is bound to
             | become a competitor for the same resources.
        
           | eminence32 wrote:
           | Ah, yes, creating black holes in-situ does sound more
           | reasonable.
           | 
           | As for the motivations of this civilization, I'm not sure, no
           | one has written this story yet :)
        
         | dmix wrote:
         | A moat of black holes.
        
         | nivekastoreth wrote:
         | If your tech can do that, I wonder if it may be more efficient
         | to just throw neutron stars around to disrupt star formation
        
       | phendrenad2 wrote:
       | So let me see if I'm understanding this, knowing nothing about
       | cosmology other than what I've read on Wikipedia:
       | 
       | Black holes pull in matter, but as the matter falls into the
       | black hole, before it reaches the event horizon, it starts to
       | collide into other matter, which can cause a lot of heating,
       | which can cause gas jets to erupt outward. In the case of a
       | supermassive black hole (such as the one theorized to be at the
       | center of our galaxy), the gas jets could be so massive and hot
       | that the gas could pull itself together (via gravity) and become
       | one or more stars.
        
         | nivekastoreth wrote:
         | IANAS but:
         | 
         | You were there up until the end. The gas jets aren't forming
         | stars near the black hole nor are the stars formed using
         | material from around it.
         | 
         | Instead, they are sending out the equivalent of pilot lights
         | that kick off star formation in another part of the galaxy
         | where clouds of star forming gas were already collecting
        
           | AnimalMuppet wrote:
           | I believe the jets are _compressing_ the gas clouds that were
           | already there. That definitely could trigger star formation.
        
             | nivekastoreth wrote:
             | Agreed. To go a little further: the main point of the paper
             | is that there is a subtlety with how black hole outflow can
             | effect the neighborhood:
             | 
             | 1. the outflow is so energetic that it blows the gas clouds
             | away and shuts down star formation
             | 
             | 2. the outflow is energetic enough to compress/raise the
             | temperature of the gas clouds, leading to star formation
             | 
             | This second is the newly observed mode, but there is also
             | yet more subtlety there since this burst of star formation
             | may result a reduction in future star formations, but that
             | is quickly approaching the limit of my layman/enthusiast
             | understanding.
        
       | radicaldreamer wrote:
       | garbage collection
        
         | h2odragon wrote:
         | cookie recipe. _big_ batches.
        
       | nivekastoreth wrote:
       | The title here: > "Black Hole Gives Birth to New Stars Rather
       | Than Devouring Them"
       | 
       | is misleading. The black hole is still devouring matter, in fact
       | it must have been to cause the outflow that triggered star
       | formation in another region.
       | 
       | Removing "Rather Than Devouring Them" would improve the title,
       | but better would be to simply use the title from the paper.
        
         | JALTU wrote:
         | I was going to suggest, "Black Holes Provide Umbilical Cords to
         | New Stars"
        
           | nivekastoreth wrote:
           | After I posted I was thinking and came up with "Black Hole
           | Exhaust (Can) Breathe Life Into New Star Formation," but I
           | also like yours
        
             | labster wrote:
             | Something about the way you wrote your headline makes me
             | feel like it would be on a website with headlines like "Get
             | six planets per orbit with this one weird trick" and "Which
             | frequency pulsar is right for you?".
        
             | hermitdev wrote:
             | So, instead of "made of star dust", we're "made of black
             | hole farts"?
        
         | dang wrote:
         | Ok, changed above. Thanks!
        
         | klyrs wrote:
         | Over-anthropomorphizing for self-amusement: perhaps it's merely
         | playing with its food, creating new stars that it fully intends
         | to devour in the future.
        
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