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

Abstract

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 observing cycle, but also clear evidence - at more than four sigma significance - of increased wind absorption signatures in its Doppler-broadened x-ray emission line profiles. We demonstrate this with non-parametric analysis of the profiles as well as Gaussian fitting and then use the line-profile model fitting to derive a mass-loss rate of $2.47\pm 0.09\times 10^{-6}$ Msun/yr, which is a 40 per cent increase over the value obtained from the cycle 1 data. The increase in the individual emission line fluxes is greater for short-wavelength lines than long-wavelength lines, as would be expected if a uniform increase in line emission is accompanied by an increase in the wavelength-dependent absorption by the cold wind in which the shock-heated plasma is embedded.

Accepted by MNRAS. No longer a letter, but rather a nine page paper with several multi-panel figures showing all the line profiles. We have now included an analysis of the entire cycle 19 data set and present two model-independent confirmations of the line profile changes

References in corpus (4)

• BRITE-Constellation high-precision time-dependent photometry of the early-O-type supergiant $\zeta$ Puppis unveils the photospheric drivers of its small- and large-scale wind structures
• Wind signatures in the X-ray emission line profiles of the late O supergiant $\zeta$ Orionis
• A Deep Exposure in High Resolution X-Rays Reveals the Hottest Plasma in the $\zeta$Puppis Wind
• A detailed X-ray investigation of zeta Puppis IV. Further characterization of the variability

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• Observed epochal variations in X-ray lines from the O Supergiant $\zeta$ Puppis do not require substantial changes in the wind mass flux
• Methods to Test the Source of the Extreme Gas Motions in WS 35