White Dwarfs Form Exceptional Habitable Conditions for Exoplanets

[Spinward Flow]

 

[aramis]

Competing studies at work.
The best things about white dwarves are the incredible stability, and the long duration expected.
the worst thing? They only get worse with time.
But at least it takes a long time.

 

[Condottiere]

And then, the God Emperor annexes it.

 

[agorski]

The existence of a White Dwarf implies that any planets have had their atmospheres and oceans stripped off.

 

[aramis]

The existence of a White Dwarf implies that any planets have had their atmospheres and oceans stripped off.

Implies but does not ensure. A strong enough magnetic field can retain some. Various processes can result in new atmosphere. And the more eccentric orbits are more likely to be affected by the blast – those on an inbound leg when the supernova happens will get slowed or reversed, making it possible to get a fresh run of comets, and hence also volatiles.

 

[Daidoji Dave]

Watching the vid I wondered if the habitable zone of a white dwarf would fall inside the star's jump shadow. Taking the 100 diameter limit very literally it seems not (white dwarfs are dense but small), but if you extrapolated to mass a habitable planet might be shadowed.

 

[Spinward Flow]

Watching the vid I wondered if the habitable zone of a white dwarf would fall inside the star's jump shadow. Taking the 100 diameter limit very literally it seems not (white dwarfs are dense but small), but if you extrapolated to mass a habitable planet might be shadowed.

That's the problem with the 100D "fudge" for jump shadows.
It works for planets (kinda sorta) because they fall into a relatively narrow density range (0.6 - 12 g/cm³).

Stars, however ... have a slightly wider range of possible matter densities.

1. Main Sequence Stars:
   • Sun-like stars (G2v): Have a mean density of about 1.4 g/cm³.
   • O5v stars (massive, hot): Have a mean density of about 0.005 g/cm³.
   • M0v stars (small, cool): Have a mean density of about 5 g/cm³.
2. Giant and Supergiant Stars:
   • Giants: Low-density stars, with mean densities around 10^-7 g/cm³ (e.g., K5III).
   • Supergiants: Very low-density stars, with mean densities around 10^-9 g/cm³ (e.g., M2I).
3. Compact Stellar Remnants:
   • White Dwarfs: High-density stars, with mean densities around 10⁵ g/cm³.
   • Neutron Stars: Extremely dense objects, with densities ranging from 3.7×10¹⁷ to 5.9×10¹⁷ kg/m³ (2.6×10¹⁴ to 4.1×10¹⁴ times the density of the Sun).
     • A teaspoon of neutron star material would weigh over 5.5×10¹² kg (about 900 times the mass of the Great Pyramid of Giza).
     • The entire mass of the Earth at neutron star density would fit into a sphere 305m in diameter.
     • The gravitational field at a neutron star's surface is about 2×10¹¹ times stronger than on Earth.

For the more mathematically minded, the better solution to the question would be to determine an "acceleration threshold" limit (in m/s²) that is the limit of a jump shadow. Above that acceleration limit, you're inside a jump shadow ... below that acceleration limit you're outside a jump shadow. That way it becomes less a matter of "proximity" to other masses (100 diameters) and more a measure of "gravitational force" being applied that is actually a curvature of spacetime.

The problem with that more mathematically "correct" (and accurate) way of handling things is that ... it's a LOT of math ... and you need details that aren't easily encoded into simplified UWP codes.

So for "quick 'n' dirty" purposes, the 100 diameter limit is "easier to use" in the vicinity of most planets (to speed up gameplay).

 

[kilemall]

That's the problem with the 100D "fudge" for jump shadows.
It works for planets (kinda sorta) because they fall into a relatively narrow density range (0.6 - 12 g/cm³).

Stars, however ... have a slightly wider range of possible matter densities.

1. Main Sequence Stars:
   • Sun-like stars (G2v): Have a mean density of about 1.4 g/cm³.
   • O5v stars (massive, hot): Have a mean density of about 0.005 g/cm³.
   • M0v stars (small, cool): Have a mean density of about 5 g/cm³.
2. Giant and Supergiant Stars:
   • Giants: Low-density stars, with mean densities around 10^-7 g/cm³ (e.g., K5III).
   • Supergiants: Very low-density stars, with mean densities around 10^-9 g/cm³ (e.g., M2I).
3. Compact Stellar Remnants:
   • White Dwarfs: High-density stars, with mean densities around 10⁵ g/cm³.
   • Neutron Stars: Extremely dense objects, with densities ranging from 3.7×10¹⁷ to 5.9×10¹⁷ kg/m³ (2.6×10¹⁴ to 4.1×10¹⁴ times the density of the Sun).
     • A teaspoon of neutron star material would weigh over 5.5×10¹² kg (about 900 times the mass of the Great Pyramid of Giza).
     • The entire mass of the Earth at neutron star density would fit into a sphere 305m in diameter.
     • The gravitational field at a neutron star's surface is about 2×10¹¹ times stronger than on Earth.

For the more mathematically minded, the better solution to the question would be to determine an "acceleration threshold" limit (in m/s²) that is the limit of a jump shadow. Above that acceleration limit, you're inside a jump shadow ... below that acceleration limit you're outside a jump shadow. That way it becomes less a matter of "proximity" to other masses (100 diameters) and more a measure of "gravitational force" being applied that is actually a curvature of spacetime.

The problem with that more mathematically "correct" (and accurate) way of handling things is that ... it's a LOT of math ... and you need details that aren't easily encoded into simplified UWP codes.

So for "quick 'n' dirty" purposes, the 100 diameter limit is "easier to use" in the vicinity of most planets (to speed up gameplay).

When you are Grandfather, you can darn well make jumpspace do what you want.

Speaking of which, has anybody made the ‘that universe mechanic rule is Grandfathered in’ joke? Just checking.

 

[G. Kashkanun Anderson]

That's the problem with the 100D "fudge" for jump shadows.
It works for planets (kinda sorta) because they fall into a relatively narrow density range (0.6 - 12 g/cm³).

Stars, however ... have a slightly wider range of possible matter densities.

This, this, this ... this!

There is also the little matter of what is the diameter of a star, as it is defined entirely differently than that of a planet.

For main sequence and helium/helium flash stars (aka the 'not dead yet!' ones), the 'surface' is its photosphere -- the point at which light has a roughly 50/50 chance of being able to make its great escape and radiate its way out into the universe. This is, for obvious reasons, not even remotely the same thing as the surface of a planet, whether a terrestrial one or a gas giant. It's not even an apples to oranges comparison; it's more like an apples to ... I dunno ... a lobster, or a paramecium, or something like that.

To put an even more ridiculous point on it by example, the density of Antares (which supposedly has a surface diameter of 1.33 billion kilometers, giving it a supposed safe jump limit of 133 billion kilometers via conventional assumptions) is approximately one 4 millionth that of Terra; or, to put another exclamation point on that exclamation point, 0.00002559% that of Earth.

Seriously, there is no reason one could not jump in or out from right on the 'surface' of Antares -- or even millions and millions of kilometers inside of it -- and suffer no ill consequences at all for that.

Now, attempting that from too close to the core of Antares, that's entirely different. But in that case we are talking about something much more akin to a planetary surface, as well as densities far above that of any conventionally formed planet.

 

[Spinward Flow]

Seriously, there is no reason one could not jump in or out from right on the 'surface' of Antares -- or even millions and millions of kilometers inside of it -- and suffer no ill consequences at all for that.

This is one of the quirks of physics that I learned in class.

Obligatory physicist vs engineer joke incoming:

• Physicist: Assume a spherical chicken of uniform density-
• Engineer: HOLD IT!

One of the curious things about gravity calculations is that if you take a perfect sphere and slice it up into infinitely many thin "shell" slices (so you can do calculus integrations) something slightly counterintuitive happens, so long as the density remains constant for each "layer" of the shells you're calculating.

Whatever distance you are from the focal point of the (perfect) sphere ... you only need to calculate using the total mass of the spherical radius below you in order to work out what the (local) gravity acceleration is at that point. Any "shells" of (spherical) matter that are farther away from the core (basically, higher altitudes) actually work out to effectively a NET ZERO gravitational effect.

The math for it gets complicated, but the point is that if you're "halfway to the core" of a planet, for the purposes of (local, felt) gravity calculations, you only need to know the (spherical) mass "below" your location ... while all the mass "above" you effectively cancels out to be a net zero gravity effect, because of the shape of the sphere (and the uniform density of the matter in the idealized physics modeling of what's going on when you do the calculus integrals for everything).



The reason why I bring this up is because if a craft were to "fly into a star" ... the plasma field extending beyond the craft's location toward the photosphere wouldn't have any gravitational effect on the craft at all, only the mass of the star closer to the core than craft would.

Assuming the star is perfectly spherical and has no "turbulence" going on causing the matter of the star to "bubble" otherwise "churn" in ways that would compute as asymmetrical ... which (spoiler alert) will not be true for ANY STAR with active nuclear fusion happening in its core.



The reason why I mention this is because the example we used in physics class for this was a hollow planet (with people walking around on the inside of the lithosphere crust) or a conceptual dyson sphere with an inhabited interior. Absent a rotational spin to centrifuge the interior outwards, the entire interior of a "hollow world" would be in zero gravity ... while people on the exterior of the hollow shell would experience gravity levels of ONLY the mass of that hollow shell.

Just one of those quirky bits of ... "huh ..." that sticks with you.

 

[kilemall]

How about grandfather built jumpspace to be affected by diameters, mass and gravity is trivial cause higher dimensional engineering, and it just is.

 

[willtron3030]

How about grandfather built jumpspace to be affected by diameters, mass and gravity is trivial cause higher dimensional engineering, and it just is.

Grandfather was a Freemason, and it's all about "Sacred Geometry".

 

[Krikkitone]

That's the problem with the 100D "fudge" for jump shadows.
It works for planets (kinda sorta) because they fall into a relatively narrow density range (0.6 - 12 g/cm³).

Stars, however ... have a slightly wider range of possible matter densities.

1. Main Sequence Stars:
   • Sun-like stars (G2v): Have a mean density of about 1.4 g/cm³.
   • O5v stars (massive, hot): Have a mean density of about 0.005 g/cm³.
   • M0v stars (small, cool): Have a mean density of about 5 g/cm³.
2. Giant and Supergiant Stars:
   • Giants: Low-density stars, with mean densities around 10^-7 g/cm³ (e.g., K5III).
   • Supergiants: Very low-density stars, with mean densities around 10^-9 g/cm³ (e.g., M2I).
3. Compact Stellar Remnants:
   • White Dwarfs: High-density stars, with mean densities around 10⁵ g/cm³.
   • Neutron Stars: Extremely dense objects, with densities ranging from 3.7×10¹⁷ to 5.9×10¹⁷ kg/m³ (2.6×10¹⁴ to 4.1×10¹⁴ times the density of the Sun).
     • A teaspoon of neutron star material would weigh over 5.5×10¹² kg (about 900 times the mass of the Great Pyramid of Giza).
     • The entire mass of the Earth at neutron star density would fit into a sphere 305m in diameter.
     • The gravitational field at a neutron star's surface is about 2×10¹¹ times stronger than on Earth.

For the more mathematically minded, the better solution to the question would be to determine an "acceleration threshold" limit (in m/s²) that is the limit of a jump shadow. Above that acceleration limit, you're inside a jump shadow ... below that acceleration limit you're outside a jump shadow. That way it becomes less a matter of "proximity" to other masses (100 diameters) and more a measure of "gravitational force" being applied that is actually a curvature of spacetime.

The problem with that more mathematically "correct" (and accurate) way of handling things is that ... it's a LOT of math ... and you need details that aren't easily encoded into simplified UWP codes.

So for "quick 'n' dirty" purposes, the 100 diameter limit is "easier to use" in the vicinity of most planets (to speed up gameplay).

I found if you have it based on tidal forces, then it essentially is diameter * density…. ie 100 D from same mass of “standard” density

It means you can jump into the outside edge of a red giant star….. but one could probably just add in a maximum local density to deal with that.