# How much hydrogen could you amass before it would form a black hole? **URL:** \ **Category:** Factual Questions\ **Created:** [August 31, 2015, 8:32pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540 "2015-08-31T20:32:01Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![sweeteviljesus](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sweeteviljesus](https://boards.straightdope.com/u/sweeteviljesus)\ **Post date:** [August 31, 2015, 8:32pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/1 "2015-08-31T20:32:01Z")
If you could pile up plain hydrogen and have it overcome the solar wind generated, could you gather up enough that it would undergo gravitational collapse? Thanks, Rob ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [August 31, 2015, 9:08pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/2 "2015-08-31T21:08:51Z")
If you gathered up enough hydrogen, it would form a star and the energy from the nuclear fusion would keep it from collapsing further for a while. Once the fuel runs out (though a series of other reactions) it would collapse into black dwarf, neutron star, or black hole depending on how much is left. If the remaining matter is 3 times the mass of our sun it will form a black hole. A quick search indicates that it would need to start the process with 25 solar masses to end up with 3 solar masses after burning for that long and the inevitable supernova near the end of the cycle. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [August 31, 2015, 9:12pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/3 "2015-08-31T21:12:51Z")
It would undergo nuclear fusion long before nuclear degeneration. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2015, 9:22pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/4 "2015-08-31T21:22:39Z")
Get more hydrogen, and it’ll still burn before it goes black; it’ll just burn quicker. Eventually, though, there is some quantity of hydrogen that would go black before it burned (but which would still burn at some point before reaching the singularity). ---
**Author:** ![sweeteviljesus](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sweeteviljesus](https://boards.straightdope.com/u/sweeteviljesus)\ **Post date:** [August 31, 2015, 9:27pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/5 "2015-08-31T21:27:50Z")
How much? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [August 31, 2015, 9:31pm UTC](https://boards.straightdope.com/t/how-much-hydrogen-could-you-amass-before-it-would-form-a-black-hole/729540/6 "2015-08-31T21:31:15Z")
> [@sweeteviljesus](#): > > How much? 25 solar masses, and a whole lot of time.