Nearby white dwarf found, ready to go supernova

Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.

Yousuf Khan

Science Centric | News | XMM-Newton uncovers a celestial Rosetta stone
"Astronomers have been on the trail of this mysterious object since
1997, when they discovered that something was giving off X-rays near the
bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity,
the mysterious object has been tracked along its orbit. The observation
has shown it to be a white dwarf, the dead heart of a star, shining
X-rays into space."
http://www.sciencecentric.com/news/a...-rosetta-stone

The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion
"The subdwarf, which prob-
ably has a mass between 0.7 − 1.3M⊙, is the descendant of a
massive asymptotic giant branch star that lost its hydrogen-rich
outer layers in a common-envelope event."
http://74.125.113.132/search?q=cache...n t=firefox-a

On Sep 6, 10:01Â*am, Yousuf Khan wrote:
Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.

Â* Â* Â* Â* Yousuf Khan

Science Centric | News | XMM-Newton uncovers a celestial Rosetta stone
"Astronomers have been on the trail of this mysterious object since
1997, when they discovered that something was giving off X-rays near the
bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity,
the mysterious object has been tracked along its orbit. The observation
has shown it to be a white dwarf, the dead heart of a star, shining
X-rays into space."http://www.sciencecentric.com/news/article.php?q=09090422-xmm-newton-...

The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion
"The subdwarf, which prob-
ably has a mass between 0.7 − 1.3M⊙, is the descendant of a
massive asymptotic giant branch star that lost its hydrogen-rich
outer layers in a common-envelope event."http://74.125.113.132/search?q=cache:C7yAyloGuroJ:www.phys.uu.nl/~pol...

Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.

Sirius B was originally 8+9solar masses before becoming a red
supergiant of 5+ solar masses, subsequently terminating its nova phase
into becoming a 1+ white dwarf that's nicely sucking away at Sirius A
on each and every near pass. At some point Sirius A+B could merge and
become yet another nova, and possibly evolve into a binary white dwarf
system, or into becoming a singular and somewhat larger white dwarf
that'll supposedly remain stable for billions of years.

The bad new is, Sirius is too close and only getting closer for our
level of discomfort tolerance, whereas human life as we've known Eden/
Earth to support may not be as local nova immune as we'd care to
think.

Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet�

On Sep 6, 9:46Â*am, BradGuth wrote:
On Sep 6, 10:01Â*am, Yousuf Khan wrote:





Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.

Â* Â* Â* Â* Yousuf Khan

Science Centric | News | XMM-Newton uncovers a celestial Rosetta stone
"Astronomers have been on the trail of this mysterious object since
1997, when they discovered that something was giving off X-rays near the
bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity,
the mysterious object has been tracked along its orbit. The observation
has shown it to be a white dwarf, the dead heart of a star, shining
X-rays into space."http://www.sciencecentric.com/news/article.php?q=09090422-xmm-newton-...

The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion
"The subdwarf, which prob-
ably has a mass between 0.7 − 1.3M⊙, is the descendant of a
massive asymptotic giant branch star that lost its hydrogen-rich
outer layers in a common-envelope event."http://74.125.113.132/search?q=cache:C7yAyloGuroJ:www.phys.uu.nl/~pol...

Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.

Sirius B was originally 8+9solar masses before becoming a red
supergiant of 5+ solar masses, subsequently terminating its nova phase
into becoming a 1+ white dwarf that's nicely sucking away at Sirius A
on each and every near pass. Â*At some point Sirius A+B could merge and
become yet another nova, and possibly evolve into a binary white dwarf
system, or into becoming a singular and somewhat larger white dwarf
that'll supposedly remain stable for billions of years.

The bad new is, Sirius is too close and only getting closer for our
level of discomfort tolerance, whereas human life as we've known Eden/
Earth to support may not be as local nova immune as we'd care to
think.

Â*Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenetâ€�- Hide quoted text -

- Show quoted text -

Stars don't exchange matter except it is possible by their stellar
winds. But this is insignifricant mass.

Mitch Raemsch

On Sep 6, 10:59Â*am, BURT wrote:
On Sep 6, 9:46Â*am, BradGuth wrote:



On Sep 6, 10:01Â*am, Yousuf Khan wrote:

Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf..

Â* Â* Â* Â* Yousuf Khan

Science Centric | News | XMM-Newton uncovers a celestial Rosetta stone
"Astronomers have been on the trail of this mysterious object since
1997, when they discovered that something was giving off X-rays near the
bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity,
the mysterious object has been tracked along its orbit. The observation
has shown it to be a white dwarf, the dead heart of a star, shining
X-rays into space."http://www.sciencecentric.com/news/article.php?q=09090422-xmm-newton-...

The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion
"The subdwarf, which prob-
ably has a mass between 0.7 − 1.3M⊙, is the descendant of a
massive asymptotic giant branch star that lost its hydrogen-rich
outer layers in a common-envelope event."http://74.125.113.132/search?q=cache:C7yAyloGuroJ:www.phys.uu.nl/~pol...

Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.

Sirius B was originally 8+9solar masses before becoming a red
supergiant of 5+ solar masses, subsequently terminating its nova phase
into becoming a 1+ white dwarf that's nicely sucking away at Sirius A
on each and every near pass. Â*At some point Sirius A+B could merge and
become yet another nova, and possibly evolve into a binary white dwarf
system, or into becoming a singular and somewhat larger white dwarf
that'll supposedly remain stable for billions of years.

The bad new is, Sirius is too close and only getting closer for our
level of discomfort tolerance, whereas human life as we've known Eden/
Earth to support may not be as local nova immune as we'd care to
think.

Â*Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenetâ€�- Hide quoted text -

- Show quoted text -

Stars don't exchange matter except it is possible by their stellar
winds. But this is insignifricant mass.

Mitch Raemsch

But stars do merge (run into one another). Or doesn't trajectory and
gravity count for anything?

~ BG

BradGuth wrote:
On Sep 6, 10:01 am, Yousuf Khan wrote:
Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.
Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.


Read it again, it's a white dwarf, so it doesn't need to be
supermassive. It accretes mass off its companion and heads towards the
Chandresekhar Limit.

Yousuf Khan

On Sep 6, 4:09*pm, Yousuf Khan wrote:
BradGuth wrote:
On Sep 6, 10:01 am, Yousuf Khan wrote:
Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.
Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.

Read it again, it's a white dwarf, so it doesn't need to be
supermassive. It accretes mass off its companion and heads towards the
Chandresekhar Limit.

* * * * Yousuf Khan

Exactly like Sirius-B, although Sirius-A is kind of a wussy star to
draw from.

~ BG

On Sep 6, 2:20Â*pm, BradGuth wrote:
On Sep 6, 10:59Â*am, BURT wrote:





On Sep 6, 9:46Â*am, BradGuth wrote:

On Sep 6, 10:01Â*am, Yousuf Khan wrote:

Type Ia supernova forming within the galaxy. The white dwarf's companion
is now in the range of 0.7 to 1.3 solar masses, and it may have been
much more massive before but lost much of its mass to the white dwarf.

Â* Â* Â* Â* Yousuf Khan

Science Centric | News | XMM-Newton uncovers a celestial Rosetta stone
"Astronomers have been on the trail of this mysterious object since
1997, when they discovered that something was giving off X-rays near the
bright star HD 49798. Now, thanks to XMM-Newton's superior sensitivity,
the mysterious object has been tracked along its orbit. The observation
has shown it to be a white dwarf, the dead heart of a star, shining
X-rays into space."http://www.sciencecentric.com/news/article.php?q=09090422-xmm-newton-...

The nature of the bright subdwarf HD 49798 and its X-ray pulsating companion
"The subdwarf, which prob-
ably has a mass between 0.7 − 1.3M⊙, is the descendant of a
massive asymptotic giant branch star that lost its hydrogen-rich
outer layers in a common-envelope event."http://74.125.113.132/search?q=cache:C7yAyloGuroJ:www.phys.uu.nl/~pol...

Anything less than 8 solar masses is not likely to become a full blown
supernova, but instead just another pesky nova that could expand its
molecular debris out to a dozen some odd light years radii.

Sirius B was originally 8+9solar masses before becoming a red
supergiant of 5+ solar masses, subsequently terminating its nova phase
into becoming a 1+ white dwarf that's nicely sucking away at Sirius A
on each and every near pass. Â*At some point Sirius A+B could merge and
become yet another nova, and possibly evolve into a binary white dwarf
system, or into becoming a singular and somewhat larger white dwarf
that'll supposedly remain stable for billions of years.

The bad new is, Sirius is too close and only getting closer for our
level of discomfort tolerance, whereas human life as we've known Eden/
Earth to support may not be as local nova immune as we'd care to
think.

Â*Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenetâ€�- Hide quoted text -

- Show quoted text -

Stars don't exchange matter except it is possible by their stellar
winds. But this is insignifricant mass.

Mitch Raemsch

But stars do merge (run into one another). Â*Or doesn't trajectory and
gravity count for anything?

Â*~ BG- Hide quoted text -

- Show quoted text -

No. Rarely. It has never been observed in astronomy. Gravity tends to
keep stars in orbit not flying into one another. If that was true
eventually all stars would collide. And that is simply not the case.

Mitch Raemsch

Yousuf Khan wrote:
[...]

To be "ready to go" means that they have an understanding of the accretion
rate and the existing stockpile of hydrogen on the star's surface.

Their entire basis is knowing that the mass of the object [within
50%...laff] is that it is close to the Chandrasakhar limit, which has proben
to be rather fungible.

No accretion rate, no timeframe.

On Sep 6, 10:09*pm, eric gisse wrote:
To be "ready to go" means that they have an understanding of the accretion
rate and the existing stockpile of hydrogen on the star's surface.

Their entire basis is knowing that the mass of the object [within
50%...laff] is that it is close to the Chandrasakhar limit, which has proben
to be rather fungible.

No accretion rate, no timeframe.

I don't know if they don't have an accretion rate or not, more likely
it just wasn't mentioned in this article.

Yousuf Khan


Eric Gisse isn't subscribed to the “Sci.Astro� news·group;
so, unless he Googles it, he won't see your reply, Yousuf Khan.

He has me plonked, so he won't see this either.

Eric's news·reader, knode, automatically adds the mono·group followup:
Followup-To: sci.astro

As a former Google·Groups user, Eric doesn't understand
that he asked you to move to a news·group that he doesn't read.
························
For those just now tuning in, the heritage of this post is:
―― Oldest ancestor first ――
Yousuf•Khan
eric•gisse
Yousuf•Khan
Sci.Astro
Google·, ISO-8859-1, 70.49.137.78, Gecko➤Jun·2009➤XP, Sep 6, 2009
Nearby white dwarf found, ready to go supernova