Tomography of the Atmosphere of Long-Period Variable Stars

Abstract

This paper presents a new tomographic technique to derive the velocity feld across the atmosphere of long-period variable (LPV) stars. The method crosscorrelates the optical spectrum with numerical masks constructed from synthetic spectra and probing layers of increasing depths. This technique reveals that the line doubling often observed in LPV stars around maximum light is the signature of the shock wave propagating in the atmosphere of these pulsating stars.

The word tomography is used here in its etymological sense (‘cut display’), which differs somewhat from the broader sense in use within the astronomical community (reconstruction of a structure using projections taken under different angles).