A way to measure the mass of a neutron star, even if it is byitself!!

New way to weigh a star | Astronomy.com
http://www.astronomy.com/news/2015/1...o-weigh-a-star

Until now, scientists have determined the mass of stars, planets and moons by studying their motion in relation to others nearby, using the gravitational pull between the two as the basis for their calculations. However, in the case of young pulsars, mathematicians at the University of Southampton have now found a new way to measure their mass, even if a star exists on its own in space.

“For pulsars, we have been able to use principles of nuclear physics, rather than gravity, to work out what their mass is, an exciting breakthrough which has the potential to revolutionize the way we make this kind of calculation,� said Wynn Ho of the University of Southampton.

Dear Yousuf Khan:

On Monday, October 5, 2015 at 3:12:22 PM UTC-7, Yousuf Khan wrote:
New way to weigh a star | Astronomy.com
http://www.astronomy.com/news/2015/1...o-weigh-a-star

Until now, scientists have determined the mass of
stars, planets and moons by studying their motion
in relation to others nearby, using the gravitational
pull between the two as the basis for their
calculations. However, in the case of young pulsars,
mathematicians at the University of Southampton have
now found a new way to measure their mass, even if a
star exists on its own in space.

"For pulsars, we have been able to use principles of
nuclear physics, rather than gravity, to work out
what their mass is, an exciting breakthrough which
has the potential to revolutionize the way we make
this kind of calculation," said Wynn Ho of the
University of Southampton.

Where does the incident matter stream come from, to form the pulsar's signal?

David A. Smith

On 05/10/2015 7:05 PM, dlzc wrote:
Where does the incident matter stream come from, to form the pulsar's signal?

It comes from inside the neutron star itself, when most of the time
interior is a superfluid, without resistance, it occasionally encounters
a frictional resistance in the form of the neutron star's own solid
crust. When the solid crust and the superfluid interior interfere with
each other, it causes a speed up of the rotation rate of the star. They
use this temporary speed up to measure the mass of the whole star.

Yousuf Khan

On Wednesday, October 7, 2015 at 7:09:27 PM UTC-4, Yousuf Khan wrote:
On 05/10/2015 7:05 PM, dlzc wrote:
Where does the incident matter stream come from, to form the pulsar's signal?

It comes from inside the neutron star itself, when most of the time
interior is a superfluid, without resistance, it occasionally encounters
a frictional resistance in the form of the neutron star's own solid
crust. When the solid crust and the superfluid interior interfere with
each other, it causes a speed up of the rotation rate of the star. They
use this temporary speed up to measure the mass of the whole star.

The original research paper is he http://arxiv.org/abs/1510.00395

It's an interesting concept and worth exploring. I do think it represents a very nice improvement in the understanding of pulsar physics, and it is a very nice synthesis of X-ray measurements of neutron star temperature and radio measurements timing properties.

However, I'm not sure how reliable the mass estimates will be. My recollection is that individual pulsars don't glitch in a consistent manner, which to me means that this theory should be taken with a grain of salt. Also, the results are highly dependent on the nuclear matter equation of state at high density, which is not actually known. What would be most excellent would be to estimate masses in two independent ways and then see if both methods get the same answer.

Craig Markwardt

On 09/10/2015 10:16 AM, Craig Markwardt wrote:
It's an interesting concept and worth exploring. I do think it
represents a very nice improvement in the understanding of pulsar
physics, and it is a very nice synthesis of X-ray measurements of
neutron star temperature and radio measurements timing properties.

Yup, and if it gets verified in some dual-body neutron star systems,
then we'll have a brand new way of measuring masses.

However, I'm not sure how reliable the mass estimates will be. My
recollection is that individual pulsars don't glitch in a consistent
manner, which to me means that this theory should be taken with a
grain of salt. Also, the results are highly dependent on the nuclear
matter equation of state at high density, which is not actually
known. What would be most excellent would be to estimate masses in
two independent ways and then see if both methods get the same
answer.

I don't think they need them to glitch consistently. They just need to
measure the difference in timings between normal and glitched modes,
whenever that happens.

Yousuf Khan