DavidMcC wrote:There is one way an extrasolar planet can have an oxygen atmosphere without life:

How would a planet orbiting a white dwarf still have an atmosphere of any kind? I'm assuming that star has already been through the red giant stage of its evolution.

Cito di Pense wrote:

DavidMcC wrote:There is one way an extrasolar planet can have an oxygen atmosphere without life:

How would a planet orbiting a white dwarf still have an atmosphere of any kind? I'm assuming that star has already been through the red giant stage of its evolution.

I suppose it depends on the detailed history of that particular system. Do you have any reason to suppose that there couldn't be an atmosphere on such a planet. If the star is in the main sequence and the planet is far enough away from the star, then I don't see why it couldn't hang on to at least some atmosphere.

EDIT: I suppose that the mere fact that it is an oxygen white dwarf makes it not a main sequence star straight away, doesn't it?

newolder wrote:If the star is "in the main sequence" (Hertzprung Russell) then it's not (yet) a white dwarf.

Splitting hairs, because not all stars end up as white dwarves or go through a red giant phase, or a main sequence star.

EDIT: The more massive stars, that end up as neutron stars or black holes, for example.

newolder wrote:

DavidMcC wrote:

newolder wrote:If the star is "in the main sequence" (Hertzprung Russell) then it's not (yet) a white dwarf.

Do you not understand that even main sequence stars have modes of death, oftenending up as white dwarf? : doh:

I understand that some main sequence stars shed their outer layers during a red giant phase to become white dwarf stars. Do you now understand (as shown in the diagram) that white dwarf stars are not "in the main sequence"?

I always understood that, newolder. This is a side-track. The thread was meant to be about planets with oxygen but no life, remember? Now you've taken it into competely different territory, because of a different interpretation of the terminology.
To me, the main sequence should include the death phases of the star, even if they are not called "main sequence" any more.

Time to end the detour? Sorry I misused the term, "main sequence", OK?

interesting i found this and wanted to share.
Earth's water is older than the Sun | Astronomy.com

this is indeed new story,but when i was a child,i was taught that in the begging,before the formation and evolution of the solar system,that God throne was on the water.
translated “and His Throne was on the water”

i see now clearly the connection.

We have many thrones on water where I live. They are connected to the plumbing.

Creative poo

LucidFlight wrote:We have many thrones on water where I live. They are connected to the plumbing.

I was just thinking about one of those, what a co-inkydink!

All kinds of cute little creation myths involve starting off with water.

For anyone daft enough to try and misrepresent science to support religious fables or shaky belief, the issue of the 'age' of the Solar System's water is a moronic thing to choose.
Clearly, either way, the atoms making up the water long pre-dated the solar system, the only question was how much was already in combined into H2O and survived.
And, of course, 'water' pre-dating the solar system wasn't in the form of liquid water anyway. A less-shit scriptural reference would be more like "and his throne was drifting between fucktons of mucky ice grains"