Chandra spectral measurements of the O supergiant $\zeta$ Puppis indicate a surprising increase in the wind mass-loss rate over 18 years

David H. Cohen, Jiaming Wang, Véronique Petit +4

New long Chandra grating observations of the O supergiant $\zeta$ Pup show not only a brightening of the x-ray emission line flux of 13 per cent in the 18 years since Chandra's first o…