# Rekindling a dead star

**URL:** <https://boards.straightdope.com/t/rekindling-a-dead-star/694540>\
**Category:** Factual Questions\
**Created:** [August 1, 2014, 12:37am UTC](https://boards.straightdope.com/t/rekindling-a-dead-star/694540 "2014-08-01T00:37:37Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\
**Post date:** [August 1, 2014, 12:37am UTC](https://boards.straightdope.com/t/rekindling-a-dead-star/694540/1 "2014-08-01T00:37:37Z")

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Reading about Stellar Evolution, I see that one type of stellar remnant is a White Dwarf. This is a mass that just sits there radiating heat until it becomes a black dwarf. If enough mass is added, it can become a Neutron Star. Even more mass can tip it past the Chandrasekhar limit to collapse into a Black Hole. But can a White Dwarf ever become a new fusion-powered main sequence star if enough Hydrogen is added quickly, say, through a trip through a dense nebula of H2? Or maybe a close encounter with another star that sucks away a large portion of the H2 from that star?

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**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\
**Post date:** [August 1, 2014, 12:43am UTC](https://boards.straightdope.com/t/rekindling-a-dead-star/694540/2 "2014-08-01T00:43:33Z")

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From [Wikipedia’s article on Supernova:](http://en.wikipedia.org/wiki/Supernova)

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> A white dwarf star may accumulate sufficient material from a stellar companion to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. There are three avenues by which this detonation is theorized to happen: stable accretion of material from a companion, the collision of two white dwarfs, or accretion that causes ignition in a shell that then ignites. The dominant mechanism by which Type Ia supernovae are produced remains unclear.

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**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\
**Post date:** [August 1, 2014, 8:07am UTC](https://boards.straightdope.com/t/rekindling-a-dead-star/694540/3 "2014-08-01T08:07:48Z")

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R S Ophiuchi is a recurrent nova, exploding every 20 years or so as hydrogen is transferred from the nearby red giant companion; see this image by the marvellous David Hardy.

> **[APOD: 2006 July 26 - Explosions from White Dwarf Star RS Oph](https://apod.nasa.gov/apod/ap060726.html)**
>
> A different astronomy and space science
> related image is featured each day, along with a brief explanation.

eventually this star might explode as a type 1a supernova.

You could try to engineer this sort of event so it happens in a more controlled fashion - perhaps by diverting a gas giant then ripping it apart so that the hydrogen falls onto the star. But to be honest this is a very inefficient process, and you would be better of trying to use the gas giant in other ways.

Note that one way to use a white dwarf is to use its own luminosity directly. These objects start off very hot, radiating in the high ultraviolet - but over time they cool, until they reach Sun-like temperatures. There are several nearby white dwarfs that are just as yellow as the Sun, and you could build a habitat at a distance of a million kilometers or so away from the star, and take advantage of the yellow sunlight. From such a habitat the white dwarf would look identical to our own Sun, in size, temperature and colour.

If it were possible to find a planet in such a position, it could conceivably be made habitable for a billion years or so - but (unlike our Sun) the white dwarf would gradually get cooler and redder, leaving the planet locked in a permanent ice age.