This Week

Week Commencing 23 January

ASR Management Meeting

Tuesday 24 January 2017, 1pm, Physics West 229

ASR Group Meeting

Wednesday 25 January 2017, 12pm, Physics West 115

Physics Colloquium

Wednesday 25 January 2017, 4pm, Poynting Small Lecture Theatre

Speaker: Anna Watts, University of Amsterdam

Title: Thermonuclear burst oscillations: where firestorms meet fundamental

Neutron stars offer a unique environment in which to develop and test
theories of the strong force. Densities in neutron star cores can reach up
to ten times the density of a normal atomic nucleus, and the stabilising
effect of gravitational confinement permits long-timescale weak
interactions. This generates matter that is neutron-rich, and opens up the
possibility of stable states of strange matter, something that can only
exist in neutron stars. Strong force physics is encoded in the Equation of
State (EOS), the pressure-density relation, which links to macroscopic
observables such as mass M and radius R via the stellar structure equations.
By measuring and inverting the M-R relation we can recover the EOS and
diagnose the underlying dense matter physics.

One very promising technique for simultaneous measurement of M and R
exploits hotspots (burst oscillations) that form on the neutron star surface
when material accreted from a companion star undergoes a thermonuclear
explosion (a Type I X -ray burst). As the star rotates, the hotspot gives
rise to a pulsation. Relativistic effects then encode information about M
and R into the pulse profile. However the mechanism that generates burst
oscillations remains unknown, 20 years after their discovery. Ignition
conditions, flame spread, and the magnetohydrodynamics of the star's ocean
all play a role. I will review the progress that we are making towards
cracking this long-standing problem, and establishing burst oscillations as
a tool par excellence for measuring M and R. This is a major goal for future
large area X-ray telescopes such as eXTP and STROBE -X.

Astronomy in the City

Wednesday 25 January 2017, 5.30pm, Poynting Large lecture Theatre

Tickets and full details of the evening are available here:

We will be having a talk from Tiago Campante asteroseismology and hunting
for exoplanets as well as the usual activities.


Using red clump stars to correct the Gaia DR1 parallaxes

Davies, G.R. and Lund, M.N. and Miglio, A. and Elsworth, Y. and Kuszlewicz, 
J.S. and North, T.S.H. and Rendle, B. and Chaplin, W.J. and Rodrigues, T.S. 
and Campante, T.L. and Girardi, L. and Hale, S.J. and Hall, O. and Jones, C.
D. and Kawaler, S.D. and Roxburgh, I. and Schofield, M.  []


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