Two white dwarf stars orbiting each other every five minutes, confirmed

These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

Yousuf Khan

***
SPACE.com -- Fastest Orbiting Stars Circle Each Other in Mere Minutes
"After a decade of mystery, astronomers have now shown that a pair of
white dwarf stars spin around each other in just 5.4 minutes, making
them the fastest-orbiting and tightest binary star system ever found,
the researchers claim.

The record-setting stellar duo, known as HM Cancri or RX J0806.3+1527,
offer challenges in explaining how such a system might form. The
super-quick stars may also present a great future test-bed for detecting
gravitational waves, which are elusive ripples in space-time."
http://www.space.com/scienceastronom...rs-100309.html

Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

How long should it be before we see the merger?

Andrew Usher

On Mar 9, 4:29*pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

How long should it be before we see the merger?

Andrew Usher

At 1600 light years, it probably already happened as of more than a
thousand years ago.

~ BG

Brad Guth wrote:
On Mar 9, 4:29*pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

How long should it be before we see the merger?

Andrew Usher

At 1600 light years, it probably already happened as of more than a
thousand years ago.

Can anyone confirm this? Guth is hardly reliable, and I have no idea
how to calculate it myself.

Andrew Usher

On Mar 10, 6:40*pm, Andrew Usher wrote:
Brad Guth wrote:
On Mar 9, 4:29*pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

How long should it be before we see the merger?

Andrew Usher

At 1600 light years, it probably already happened as of more than a
thousand years ago.

Can anyone confirm this? Guth is hardly reliable, and I have no idea
how to calculate it myself.

Andrew Usher

JPL has way more than enough supercomputer and those 3D interactive
simulators for orbital motions that'll make such matters child's play.

There's actually any dozen or more public funded supercomputers that
are over-qualified as is, so don't blame little old me.

It has been a good 8+ years, so the rate of those X-ray cycles of
321.5 seconds has changed by what amount?

~ BG

On Mar 10, 9:53*pm, Brad Guth wrote:
On Mar 10, 6:40*pm, Andrew Usher wrote:



Brad Guth wrote:
On Mar 9, 4:29*pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.

How long should it be before we see the merger?

Andrew Usher

At 1600 light years, it probably already happened as of more than a
thousand years ago.

Can anyone confirm this? Guth is hardly reliable, and I have no idea
how to calculate it myself.

snip

Andrew Usher wrote:
On Mar 10, 9:53 pm, Brad Guth wrote:
On Mar 10, 6:40 pm, Andrew Usher wrote:
Brad Guth wrote:
On Mar 9, 4:29 pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.
How long should it be before we see the merger?
Andrew Usher
At 1600 light years, it probably already happened as of more than a
thousand years ago.
Can anyone confirm this? Guth is hardly reliable, and I have no idea
how to calculate it myself.

snip

I think the major problem here is calculating frame dragging friction,
which requires Einstein's equations. I don't know how to do it, myself.
The 1600 light-year distance between us and this system is a negligible
calculation by comparison.

Yousuf Khan

On Mar 11, 2:35*pm, Yousuf Khan wrote:
Andrew Usher wrote:
On Mar 10, 9:53 pm, Brad Guth wrote:
On Mar 10, 6:40 pm, Andrew Usher wrote:
Brad Guth wrote:
On Mar 9, 4:29 pm, Andrew Usher wrote:
Yousuf Khan wrote:
These two white dwarfs are so close together, that they might fall into
each other some day. This would be an ideal test to see if two white
dwarfs falling into each other produce a Type Ia supernova, leaving
nothing behind. Or if they simply turn into a neutron star.
How long should it be before we see the merger?
Andrew Usher
At 1600 light years, it probably already happened as of more than a
thousand years ago.
Can anyone confirm this? Guth is hardly reliable, and I have no idea
how to calculate it myself.

snip

I think the major problem here is calculating frame dragging friction,
which requires Einstein's equations. I don't know how to do it, myself.
The 1600 light-year distance between us and this system is a negligible
calculation by comparison.

* * * * Yousuf Khan

Binary dwarfs as tidal locked, separated by just 80,000 km and .37
solar mass each.

“ABSTRACT. RX J0806.3+1527 is an ultracompact, double-degenerate
binary with the shortest known orbital period (321.5 s). Hakala et al.
have recently reported new optical measurements of the orbital
frequency of the source indicating that the frequency has increased
over the 9 yr since the earliest ROSAT observations.”

http://www.iop.org/EJ/article/0004-6...2306.text.html
RX J0806.3+1527 is a candidate double-degenerate binary with possibly
the shortest known orbital period. The source shows an 100% X-ray
intensity modulation at the putative orbital frequency of 3.11 mHz
(321.5 s). If the system is a detached, ultracompact binary,
gravitational radiation should drive spin-up with a magnitude of
10-16 Hz s-1. Efforts to constrain the X-ray frequency evolution to
date have met with mixed success, principally due to the sparseness of
earlier observations. Here we describe the results of the first phase-
coherent X-ray monitoring campaign on RX J0806.3+1527 with Chandra. We
obtained a total of 70 ks of exposure in six epochs logarithmically
spaced over 320 days. With these data we conclusively show that the X-
ray frequency is increasing at a rate of (3.77 ± 0.8) × 10-16 Hz s-1.
Using the ephemeris derived from the new data, we are able to phase up
all the earlier Chandra and ROSAT data and show that they are
consistent with a constant = (3.63 ± 0.06) × 10-16 Hz s-1 over the
past decade. This value appears consistent with that recently derived
by Israel et al., largely from monitoring of the optical modulation,
and is in rough agreement with the solutions reported initially by
Hakala et al., based on ground-based optical observations. The large
and stable over a decade is consistent with gravitational radiation
losses driving the evolution. An intermediate polar (IP) scenario in
which the observed X-ray period is the spin period of an accreting
white dwarf appears less tenable because the observed requires an 2
× 10-8 M yr-1, which is much larger than that inferred from the
observed X-ray luminosity (although this depends on the uncertain
distance and bolometric corrections), and it is difficult to drive
such a high in a binary system with parameters consistent with all
the multiwavelength data. If the ultracompact scenario is correct,
then the X-ray flux cannot be powered by stable accretion, which would
drive the components apart, suggesting that a new type of energy
source (perhaps electromagnetic) may power the X-ray flux.
-

Clearly they are not getting further apart.

~ BG

Yousuf Khan wrote:

I think the major problem here is calculating frame dragging friction,
which requires Einstein's equations. I don't know how to do it, myself.
The 1600 light-year distance between us and this system is a negligible
calculation by comparison.

I thought it should have been calculated when this system was
discovered. Surely the merger of two white dwarfs is an interesting
occurrence! I'm wondering, if the two WDs are both ONe (making a
supernova impossible), would they become a neutron star or a black
hole?

Andrew Usher

Andrew Usher wrote:
Yousuf Khan wrote:

I think the major problem here is calculating frame dragging friction,
which requires Einstein's equations. I don't know how to do it, myself.
The 1600 light-year distance between us and this system is a negligible
calculation by comparison.

I thought it should have been calculated when this system was
discovered. Surely the merger of two white dwarfs is an interesting
occurrence! I'm wondering, if the two WDs are both ONe (making a
supernova impossible), would they become a neutron star or a black
hole?

Neutron star, if they don't blow up instead.

Yousuf Khan