Pulsating neutron stars: 4 so far!
1)LCıs may be asymmetric
(skewness)
2)
2)Relatively large pulsed
fractions: 12%-35%
3)
3)All cases: hardness ratio is
max at the pulse maximum: counter-intuitive!
Þ Beaming
effects ? (Cropper et al. 2001)
Þ
Phase-dependent cyclotron absorption?
(Haberl et al.,
2003)
Multiple abs. lines observed in 1E1207.4-5209 are more
important at the light curve trough.
The peak of the total
light curve corresponds to the phase-interval where lines are at their
minimum.
(Bignami et al., 2003, Nature)