"What it's like to walk on a dead star"

Here's an astronomy question (I'm a newcomer here) which never seems to be
answered anywhere. I've tried books, various online resources and 'Ask
Alan' etc. in Astronomy Now but never got a response. I wonder if this is
because my question is of no use in understanding how the universe got to be
as it is today, and because it also deals with a scenario that probably
won't exist for a _very_ long time into the future.

Let's limit this query to an average star like our Sun. It'll eventually
become a White Dwarf. But what then? We then hear talk of "it will fade" or
"become a cinder" and nothing more is said.

My question. What is a cold white dwarf like?

After 10s/100s of billions of years, when this planet-sized 'cinder'
eventually cools down, what will it be made of ? Will there be shells of
different elements? Presumably its surface gravity will be very high....
does this mean it will be a perfect sphere - billiard-ball smooth even on
millimetre scale? Or will mountains and stress cracks be possible on such
a structure? If you shone a torch on it, what would be the reflective
albedo, or even the 'colour' of such cold degenerate matter? Will it be a
'slippery' surface (what about its friction characteristic) or rough? Will
loose material be possible on its surface

Pointless knowledge no doubt...please excuse me if I have just asked about
one of the 'unmentionables' of astronomy. I may be the only person who is
fascinated by what it would be like to walk on the surface of what was once
a star and admire its landscape - assuming I wasn't squashed flat of
course!!. Here's hoping I won't be squashed flat here... :-)

Is anything known about this?

Many thanks.

Steve

Hi Steve


This is a question that really fires the imagination - a gold star to
you!

Even more extreme than a dead white dwarf would be a dead neutron star -
but things are probably on something of a continuum.

First thoughts are that the gravitational force would be extreme -
stellar mass, planet-sized object, definitely a squash-flat recipe.
Also, being totally degenerate, "metallic" and so probably brilliantly
reflective. Spinning rapidly too, probably, so ellipsoidal.

However, this thing would almost certainly be the core of a huge pile of
other debris - rock etc, with extensive gas atmosphere - so we're
probably dealing with something more like an outsized gas giant planet
(Jupiter's core is thought to be degenerate too.)

I suppose that, like Russian dolls, the ultimate "Omega Hades" object
(hypothesised by Fritz Zwicky many years ago to get a foot in the door
of pre-recognition) would be a black-hole-cored neutron star with outer
shells of dead white dwarf, rock etc and gas... not a good place to take
an inquisitive stroll, except in the mind...


Best wishes:


Roxof

8-)

In message , .
writes
Hi Steve


This is a question that really fires the imagination - a gold star to
you!

Even more extreme than a dead white dwarf would be a dead neutron star -
but things are probably on something of a continuum.

First thoughts are that the gravitational force would be extreme -
stellar mass, planet-sized object, definitely a squash-flat recipe.
Also, being totally degenerate, "metallic" and so probably brilliantly
reflective. Spinning rapidly too, probably, so ellipsoidal.

I doubt if anything but a millisecond pulsar would be spinning fast
enough to be markedly ellipsoidal. IIRC, an "ordinary" pulsar is the
most accurately spherical object known, though as it is also the most
accurate natural clock a tiny deviation from perfection can be detected
- there was a recent paper about this.
I'll have to think about the dead white dwarf (black dwarf) landscape,
but a neutron star has been the setting for at least three novels
('Dragon's Egg' and 'Starquake' by Robert Forward, and 'Flux' by Stephen
Baxter), and a section of Poul Anderson's novel 'The Avatar' is set on a
pulsar. Among many strange features, the enormous magnetic field
distorts atoms on the surface.
--
Remove spam and invalid from address to reply.

I'll have to think about the dead white dwarf (black dwarf) landscape,
but a neutron star has been the setting for at least three novels
('Dragon's Egg' and 'Starquake' by Robert Forward, and 'Flux' by Stephen
Baxter), and a section of Poul Anderson's novel 'The Avatar' is set on a
pulsar. Among many strange features, the enormous magnetic field
distorts atoms on the surface.


Thanks so far chaps. Asking this question does generally seem to meet with
a sphinx-like silence, as if somehow it's unproductive and of no concern to
decent astronomers. . And any answers that are forthcoming seem to rapidly
sidestep into matters pertaining to back holes and the like.

I simply want to walk on our Sun's surface in 100 billion years. That's not
so much to ask is it ?

S

In message , Skycloud
writes

I'll have to think about the dead white dwarf (black dwarf) landscape,
but a neutron star has been the setting for at least three novels
('Dragon's Egg' and 'Starquake' by Robert Forward, and 'Flux' by Stephen
Baxter), and a section of Poul Anderson's novel 'The Avatar' is set on a
pulsar. Among many strange features, the enormous magnetic field
distorts atoms on the surface.


Thanks so far chaps. Asking this question does generally seem to meet with
a sphinx-like silence, as if somehow it's unproductive and of no concern to
decent astronomers. . And any answers that are forthcoming seem to rapidly
sidestep into matters pertaining to back holes and the like.

I simply want to walk on our Sun's surface in 100 billion years. That's not
so much to ask is it ?


Unless you mean a British billion I suspect that isn't long enough, and
you need several more zeroes. I should look it up, but I think a white
dwarf will still be respectably hot by then.
Which prompts a question I thought of after posting my first response.
Will electron degeneracy still maintain the black dwarf if it is near
room temperature, or will it be in danger of collapsing to form a
neutron star?
The surface gravity of a white dwarf is apparently about 200,000G, which
is about the same as a laboratory ultracentrifuge, so I would think the
surface will have small features if it is solid.
And yet another question. Could an instrument be built to withstand that
force? What's the deceleration on the penetrator probes the Japanese
plan to drop onto the Moon, for instance?
I doubt you'll get a sphinx-like silence round here!

In article ,
lid says...
The surface gravity of a white dwarf is apparently about 200,000G, which
is about the same as a laboratory ultracentrifuge


WOW!! A quick web search produced a link to the Beckman XL 90 which can
produce forces of 802,400g. I can't fathom how such a machine could be
built without it tearing itself apart.

You learn something new every day.

--
Alan LeHun

WOW!! A quick web search produced a link to the Beckman XL 90 which can
produce forces of 802,400g. I can't fathom how such a machine could be
built without it tearing itself apart.

Wow, that is some spin dryer.

http://www.gmi-inc.com/Genlab/beckman%20XL90.jpg

Can it dry my knickers in less than a minute?


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie

Why not a British billion? It's primarily a British newsgroup (hence the uk
in the name), and multiplying by a million at a time is more logical in that
the prefix indicates the power of a million involved (an American billion
isn't ANY rational number squared). Just to show that this isn't blind
jingoism I do acknowledge that Americans use the phrase "public school" more
sensibly.

"Jonathan Silverlight" wrote
in message ...
In message , Skycloud
writes
Thanks so far chaps. Asking this question does generally seem to meet
with
a sphinx-like silence, as if somehow it's unproductive and of no concern
to
decent astronomers. . And any answers that are forthcoming seem to
rapidly
sidestep into matters pertaining to back holes and the like.

I simply want to walk on our Sun's surface in 100 billion years. That's
not
so much to ask is it ?


Unless you mean a British billion I suspect that isn't long enough, and
you need several more zeroes. I should look it up, but I think a white
dwarf will still be respectably hot by then.
Which prompts a question I thought of after posting my first response.
Will electron degeneracy still maintain the black dwarf if it is near
room temperature, or will it be in danger of collapsing to form a
neutron star?
The surface gravity of a white dwarf is apparently about 200,000G, which
is about the same as a laboratory ultracentrifuge, so I would think the
surface will have small features if it is solid.
And yet another question. Could an instrument be built to withstand that
force? What's the deceleration on the penetrator probes the Japanese
plan to drop onto the Moon, for instance?
I doubt you'll get a sphinx-like silence round here!

In message , Charles Gilman
writes

"Jonathan Silverlight" wrote
in message ...
In message , Skycloud
writes
Thanks so far chaps. Asking this question does generally seem to meet
with
a sphinx-like silence, as if somehow it's unproductive and of no concern
to
decent astronomers. . And any answers that are forthcoming seem to
rapidly
sidestep into matters pertaining to back holes and the like.

I simply want to walk on our Sun's surface in 100 billion years. That's
not
so much to ask is it ?


Unless you mean a British billion I suspect that isn't long enough, and
you need several more zeroes. I should look it up, but I think a white
dwarf will still be respectably hot by then.

Why not a British billion? It's primarily a British newsgroup (hence
the uk
in the name), and multiplying by a million at a time is more logical in
that
the prefix indicates the power of a million involved (an American
billion
isn't ANY rational number squared). Just to show that this isn't blind
jingoism I do acknowledge that Americans use the phrase "public school"
more
sensibly.

I have absolutely no problem with the British billion and I wish it had
prevailed, but the US has an obsession with being biggest, best, and
first which occasionally becomes absurd.
But I had my doubts that Skycloud was using it, and bigger doubts that a
star will have cooled substantially in 100 thousand million years.
That's only about 10 x the current age of the universe.

"Jonathan Silverlight" wrote
in message ...
In message , Charles Gilman
writes

I have absolutely no problem with the British billion and I wish it had
prevailed, but the US has an obsession with being biggest, best, and
first which occasionally becomes absurd.
But I had my doubts that Skycloud was using it, and bigger doubts that a
star will have cooled substantially in 100 thousand million years.
That's only about 10 x the current age of the universe.


You're right. I've fallen into the habit of using the US billion rather than
the British. I must say I think it's much more convenient to have the
billion come up after on the next thousand-multiple than the
million-multiple.

I was attempting to not step too far outside accepted cosmological time
frames or put people right off, by citing the mere 100 x 10(9) yrs. As has
been pointed out though, this 'room temperature star' though could well need
a full British billion years to get 'comfortable'. But really, has no
serious work been done on this?

Steve