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Two ancient white dwarfs found near the Sun: one 11 billion years,other 12 billion years old!



 
 
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  #1  
Old April 12th 12, 06:56 AM posted to sci.astro,sci.physics
Yousuf Khan[_2_]
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Default Two ancient white dwarfs found near the Sun: one 11 billion years,other 12 billion years old!

It would mean that these stars died when the universe was only 1.6
billion or 2.6 billion years old! These are the oldest white dwarfs in
our local vicinity.

Yousuf Khan

OU astronomer and colleagues identify 12-billion-year-old white dwarf
stars | e! Science News
http://esciencenews.com/articles/201...te.dwarf.stars
  #2  
Old April 12th 12, 05:38 PM posted to sci.astro,sci.physics
Sam Wormley[_2_]
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Default Two ancient white dwarfs found near the Sun: one 11 billion years,other 12 billion years old!

On 4/12/12 12:56 AM, Yousuf Khan wrote:
It would mean that these stars died when the universe was only 1.6
billion or 2.6 billion years old! These are the oldest white dwarfs in
our local vicinity.

Yousuf Khan

OU astronomer and colleagues identify 12-billion-year-old white dwarf
stars | e! Science News
http://esciencenews.com/articles/201...te.dwarf.stars


No big deal--It nice to find son really old stars in our "neighborhood".

Kilic says, "A white dwarf is like a hot stove; once the stove is off, it cools slowly over time. By measuring how cool the stove is, we can tell how long it has been off. The two stars we identified have been cooling for billions of years."


  #3  
Old April 13th 12, 06:39 AM posted to sci.astro,sci.physics
Yousuf Khan[_2_]
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Posts: 1,692
Default Two ancient white dwarfs found near the Sun: one 11 billion years,other12 billion years old!

On 12/04/2012 12:38 PM, Sam Wormley wrote:
On 4/12/12 12:56 AM, Yousuf Khan wrote:
It would mean that these stars died when the universe was only 1.6
billion or 2.6 billion years old! These are the oldest white dwarfs in
our local vicinity.

Yousuf Khan

OU astronomer and colleagues identify 12-billion-year-old white dwarf
stars | e! Science News
http://esciencenews.com/articles/201...te.dwarf.stars



No big deal--It nice to find son really old stars in our "neighborhood".


Maybe not, but it means that their precursors only had that amount of
time from the Big Bang onwards (1.6-2.6 billion years) to evolve from a
gas cloud to a white dwarf. Not a lot of time to go through all of those
stages. Unless they were massive, but not massive enough to turn into
pulsars.

Yousuf Khan
  #4  
Old April 13th 12, 02:32 PM posted to sci.astro,sci.physics
Brad Guth[_3_]
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Default Two ancient white dwarfs found near the Sun: one 11 billionyears, other 12 billion years old!

On Apr 11, 10:56*pm, Yousuf Khan wrote:
It would mean that these stars died when the universe was only 1.6
billion or 2.6 billion years old! These are the oldest white dwarfs in
our local vicinity.

* * * * Yousuf Khan

OU astronomer and colleagues identify 12-billion-year-old white dwarf
stars | e! Science Newshttp://esciencenews.com/articles/2012/04/11/ou.astronomer.and.colleag...


Our sun has perhaps an 11+ Gy existence before it too becomes a WD,
and to think that our sun is a third or possibly fourth generation
star to start off with.

I tend to favor a much older universe, that's only most recently
(latest 0.00001%) gotten our planet infected with a MRSA like pandemic
of oligarch Semites and a few too many other brown-nosed
dysfunctionals that also don't happen to believe in hell or
redemption.

Not that it really matters, but there are many here and elsewhere
that'll peg the age of our universe at least twice as old, plus others
giving it an infinite age.

A 268 km/sec fast moving WD that's of such high mass is a likely rogue/
nomad that could only be considered that old if its current mass was
due to a merger of much older and smaller mass WDs that didn't manage
to go supernova when they joined up.

Sirius(B) only lasted at best a couple hundred million years before
turning into a WD of 1 Ms. So, how the hell can they suggest the cool
(3700-4100 K) WD J1102+4113 is 12 Gy old, without knowing of roughly
where it came from.

Unless our universe is actually much older than 13.75 Gy, it seems
J1102 could simply be a very high fission metallicity BD or an
extremely massive super-planet packed with sufficient thorium that'll
vaporize at 5061K and/or uranium of 4404K.

It seems the best available science about Sirius(B) is kind of MIA
(missing in action), and direct observations of its surface or even
that of Sirius(A) still isn't possible. Go figure.

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  #5  
Old April 13th 12, 02:40 PM posted to sci.astro,sci.physics
Brad Guth[_3_]
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Default Two ancient white dwarfs found near the Sun: one 11 billionyears,other 12 billion years old!

On Apr 12, 10:39*pm, Yousuf Khan wrote:
On 12/04/2012 12:38 PM, Sam Wormley wrote:

On 4/12/12 12:56 AM, Yousuf Khan wrote:
It would mean that these stars died when the universe was only 1.6
billion or 2.6 billion years old! These are the oldest white dwarfs in
our local vicinity.


Yousuf Khan


OU astronomer and colleagues identify 12-billion-year-old white dwarf
stars | e! Science News
http://esciencenews.com/articles/201...er.and.colleag....


No big deal--It nice to find son really old stars in our "neighborhood"..


Maybe not, but it means that their precursors only had that amount of
time from the Big Bang onwards (1.6-2.6 billion years) to evolve from a
gas cloud to a white dwarf. Not a lot of time to go through all of those
stages. Unless they were massive, but not massive enough to turn into
pulsars.

* * * * Yousuf Khan


The first stars only lasted an average of a few million years, if not
less than a million years. The second generation stars lasted perhaps
at best a few hundred million years, and the third generation stars
should have been exceeding several billion years. Our sun is a third
or forth generation star, and Sirius would have to be a forth or fifth
generation star.

Lots of new stars are simply created as too big and massive to last
very long.

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  #6  
Old April 13th 12, 03:18 PM posted to sci.astro
dlzc
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Default Two ancient white dwarfs found near the Sun: one 11 billionyears,other 12 billion years old!

Dear Yousuf Khan:

On Thursday, April 12, 2012 10:39:27 PM UTC-7, Yousuf Khan wrote:
....
Maybe not, but it means that their precursors
only had that amount of time from the Big Bang
onwards (1.6-2.6 billion years) to evolve from
a gas cloud to a white dwarf.


Since we are made of supernova stuff, they likely are *our* parents.

Not a lot of time to go through all of those
stages. Unless they were massive, but not massive
enough to turn into pulsars.


Sure, they could have been. In 11 billion years pulsars could have spun one into another. The pulsar state, since we know it spins down, does end a "separate existence" in finite time.

But I wonder how accurate the "thermal aging" technique is, when the CMBR is warmer and warmer into negative time. Hard for a star to cool down quite as fast when the CMBR is 3000 K, and of course the star runs a bit hotter too. But they are pointing to well before the quench of the CMBR here, so maybe off 100,000 years. ;)

David A. Smith
  #7  
Old April 14th 12, 04:27 AM posted to sci.astro
Yousuf Khan[_2_]
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Default Two ancient white dwarfs found near the Sun: one 11 billion years,other12 billion years old!

On 13/04/2012 10:18 AM, dlzc wrote:
Dear Yousuf Khan:

On Thursday, April 12, 2012 10:39:27 PM UTC-7, Yousuf Khan wrote:
...
Maybe not, but it means that their precursors
only had that amount of time from the Big Bang
onwards (1.6-2.6 billion years) to evolve from
a gas cloud to a white dwarf.


Since we are made of supernova stuff, they likely are *our* parents.


These are white dwarfs, so not supernova stuff here.

Not a lot of time to go through all of those
stages. Unless they were massive, but not massive
enough to turn into pulsars.


Sure, they could have been. In 11 billion years pulsars could have spun one into another. The pulsar state, since we know it spins down, does end a "separate existence" in finite time.


White dwarfs, not pulsars.

But I wonder how accurate the "thermal aging" technique is, when the CMBR is warmer and warmer into negative time. Hard for a star to cool down quite as fast when the CMBR is 3000 K, and of course the star runs a bit hotter too. But they are pointing to well before the quench of the CMBR here, so maybe off 100,000 years. ;)


CMBR temperature would still be minuscule even back then when compared
to the temperature of a white dwarf at its start. What do white dwarfs
start off at? 100,000K, 150,000K? These ones have cooled all of the way
down to 3700K, which is still way higher than the CMBR temperature
today. If the CMBR is 3K today, 12 billion years ago, it was probably 10K.

Yousuf Khan
 




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