Open AccessA spectroscopic study of bright southern Cepheids – a high‐resolution view of Cepheid atmospheres
Author(s) -
Petterson O. K. L.,
Cottrell P. L.,
Albrow M. D.,
Fokin A.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09332.x
Subject(s) - cepheid variable , physics , astrophysics , observatory , amplitude , stars , line (geometry) , radial velocity , astronomy , phase (matter) , optics , geometry , mathematics , quantum mechanics
We present high‐resolution spectroscopic observations and species‐by‐species radial velocities of a number of southern Cepheids. The stars (BP Cir, V350 Sgr, AX Cir, V636 Sco, W Sgr, S Mus, β Dor, TT Aql, Y Oph, YZ Car, SW Vel, X Pup, T Mon and l Car) were observed as part of a long‐term programme at Mt John University Observatory. Radial velocities were determined with the line bisector technique, and have a precision of ∼300 m s −1 . Velocity differences as large as 30 km s −1 were found for Hα and Ca ii when referenced to the metallic line velocity curves, but more subtle variations (of 1–2 km s −1 ) were also detected in many other species. Pulsational phase anticorrelations are found between lines of Si ii and Ba ii , confirming the propagation time delay between line‐forming layers producing these two species. We find that the amplitude and phase differences between the various species increase with period.