Habitable world around a white dwarf?

[daniel l.]

Now, please bear with me here.

Is it possible (I'm not assuming likely, just possible.) that an Earth size world could physically exist within the habitable zone of a white dwarf? And if so, would it be possible for such a planet to sustain life. (yet again, possible, I'm not assuming the likelihood.)

[Steel]

6 minutes ago, daniel l. said:

Now, please bear with me here.

Is it possible (I'm not assuming likely, just possible.) that an Earth size world could physically exist within the habitable zone of a white dwarf? And if so, would it be possible for such a planet to sustain life. (yet again, possible, I'm not assuming the likelihood.)

Theoretically yes, so long as the planet wasn't destroyed by the expulsion of the star's out layers when the white dwarf formed (at the end of the day the Earth will one day orbit a white dwarf if it survives the expansion of the red giant that proceeded it - which is very unlikely). Habitability is another thing though, as white dwarfs tend to put out some fairly intense UV and X-rays which don't tend to agree well with life (at least life as we know it)

Edited May 4, 2017 by Steel

[ProtoJeb21]

35 minutes ago, daniel l. said:

Now, please bear with me here.

Is it possible (I'm not assuming likely, just possible.) that an Earth size world could physically exist within the habitable zone of a white dwarf? And if so, would it be possible for such a planet to sustain life. (yet again, possible, I'm not assuming the likelihood.)

MAYBE. It's a huge, huge, MAAAAAAAYYYYYBBEEEE. The problem with white dwarfs is that they have really messed up masses, luminosities, and temperatures that making the calculation of a stable circumstellar habitable zone quite difficult. It's possible that, like with Blue Subdwarfs such as Kepler-70, the habitable zone would be incredibly thin - less than 0.1 AU across AT MOST. If life were to exist in a white dwarf system I would place my bets on a Europa-like world or a Titan-class planet with exotic biomechanics based off of methane, nitrogen, hydrogen, or something like that. All these organisms would get their energy from chemicals in the ground or from volcanic structures.

[daniel l.]

1 minute ago, ProtoJeb21 said:

MAYBE. It's a huge, huge, MAAAAAAAYYYYYBBEEEE. The problem with white dwarfs is that they have really messed up masses, luminosities, and temperatures that making the calculation of a stable circumstellar habitable zone quite difficult. It's possible that, like with Blue Subdwarfs such as Kepler-70, the habitable zone would be incredibly thin - less than 0.1 AU across AT MOST. If life were to exist in a white dwarf system I would place my bets on a Europa-like world or a Titan-class planet with exotic biomechanics based off of methane, nitrogen, hydrogen, or something like that. All these organisms would get their energy from chemicals in the ground or from volcanic structures.

But could you successfully relocate an earth size world into the heart of the habitable zone and terraform?

[ProtoJeb21]

1 minute ago, daniel l. said:

But could you successfully relocate an earth size world into the heart of the habitable zone and terraform?

Maybe. Just maybe.

[daniel l.]

Just now, ProtoJeb21 said:

Maybe. Just maybe.

Just wondering, not only would it be a very interesting sight, (An entire planetary system fit within an area just a few times the lunar apogee!) but in trillions of years, it may be all humanity has left.

[Spaceception]

There's a 'in a nutshell'  video that briefly goes over this, but I'm on mobile right now. 

It came out today. 

Edited May 5, 2017 by Spaceception

[daniel l.]

6 minutes ago, Spaceception said:

There's a 'in a nutshell'  video that briefly goes over this, but I'm on mobile right now. 

It came out today. 

That was the inspiration

[kerbiloid]

Unlikely.

White dwarves are originally white-hot and spread UV, X-ray, gamma and charge particles in close proximitity.
Cooling down to a Sun-like temperature (and spectre) takes very long time (billions?), as their luminosity is low due to their tiny size.

So, even if a white dwarf had appeared from a large short-living stars, and its survived planets stay young after the cataclysm, all their geological (and hydro/atmospheric) history would finish before the star gets nice.
Especailly because its habitable zone (after getting nice) is very stretched and the appearing atmosphere would be blown away.

There is a hypothesis that "carbon planets" can survive and even have a hydrocarbon/methanol atmosphere and hydrosphere near a white dwarf.
(Just because there is a lot of carbon around.)
They would be tidally locked and should have dense carbonoxide or so atmosphere to be habitable, and maybe a methanol ocean with a lot of hydrocarbon goo.
Maybe something life-like can appear there.

Though, as such planet should be very close to the star, any space flights look very unlikely due to enourmous delta-V far beyond capabilities of chemical rockets.
But for sci-fi purpose they of course could build bubble houses and balloons.
Unlikely they would know metals, but should be experienced in glues and poisons.

Edited May 5, 2017 by kerbiloid

[ccoel]

16 hours ago, ProtoJeb21 said:

MAYBE. It's a huge, huge, MAAAAAAAYYYYYBBEEEE. The problem with white dwarfs is that they have really messed up masses, luminosities, and temperatures that making the calculation of a stable circumstellar habitable zone quite difficult. It's possible that, like with Blue Subdwarfs such as Kepler-70, the habitable zone would be incredibly thin - less than 0.1 AU across AT MOST. If life were to exist in a white dwarf system I would place my bets on a Europa-like world or a Titan-class planet with exotic biomechanics based off of methane, nitrogen, hydrogen, or something like that. All these organisms would get their energy from chemicals in the ground or from volcanic structures.

Huge Maybe?    MAYBE.

how that for a Huge maybe?

[cubinator]

A planet could theoretically be stable orbiting close to a white dwarf, but it would be very difficult for the planet to get there in the first place.

[rkarmark]

On 5/5/2017 at 2:07 AM, daniel l. said:

But could you successfully relocate an earth size world into the heart of the habitable zone and terraform?

if given enought boosters (and struts)

[Zeiss Ikon]

I'm going to go with "No way in hell!"

In reality, it may be "Long, long, LONG odds, but not impossible."  It's a big universe.

The big trouble is the red giant phase that all stars less than 3.5 solar masses pass through when their main sequence lifespan is expended.  For our sun, that red giant phase would extend the sun's photosphere to about the distance of Earth's orbit, after which the Earth would deorbit in a few hundred years (at most) from the drag of the solar atmosphere (the red giant phase lasts, as I recall, a billion years or so).  So, to get an Earth-sized planet in the white dwarf's Goldilocks zone, it would have to start in a Mars-equivalent orbit, roughly (or colder), to avoid being deorbited.  Then, as or after the star finishes expelling its outer layers in the form of a planetary nebula, the planet would have to make a rather precise orbital adjustment over a fairly precise time schedule -- can't come in too fast, or it'll get blasted/burnt and lose all its volatiles (gases for the most part, though anything that vaporizes at red heat would follow after the oxygen was driven off, at least from the crust), can't come in too slow or it'll lose the ejecting layers that are braking its orbit.  Finally, it has to finish in the very narrow (and constantly shrinking, though that's on the scale of millions of years) liquid-water zone around the very hot, but very small white dwarf -- that zone will, at the beginning of the white dwarf phase, be a good bit bigger than the one around M class red dwarves, but still far smaller (and narrower) than that of F, G and K class yellow dwarves like our sun, Alpha Centauri, etc.

So, for our own solar system, we'd have to have Mars migrate after the peak of the red giant phase to an orbit inside that of Venus, likely closer to that of Mercury (six of the seven planets of Trappist I are closer than Mercury is to our sun, and the outer one is frozen, but the white dwarf Sol's Goldilocks zone would start larger than that because it's hotter).  Then, the planet must somehow (no known mechanism available) migrate inward over time to remain habitable as the white dwarf, no longer generating heat but just radiating away what's left over from its collapse, cools.

And all of this has to start with a planet that hung onto its water and atmosphere through the prior three to ten billion years (main sequence lifespan of F, G, and K stars) -- Mars likely doesn't have enough water left, even if it could regenerate a useful atmsophere; you'd probably need a bigger planet, closer to the mass of Earth or Venus.