The classification of frequencies in the gamma Doradus/delta Scuti hybrid star HD 49434

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
University of Canterbury. Physics and Astronomy
Journal Title
Journal ISSN
Volume Title
Language
Date
2015
Authors
Brunsden, E.
Pollard, K.R.
Cottrell, P.L.
Wright, D.J.
De Cat, P.
Uytterhoeven, K.
Abstract

Hybrid stars of the γ Doradus and δ Scuti pulsation types have great potential for asteroseismic analysis to explore their interior structure. To achieve this, mode identifications of pulsational frequencies observed in the stars must be made, a task which is far from simple. In this work we begin the analysis by scrutinizing the frequencies found in the CoRoT photometric satellite measurements and ground-based high-resolution spectroscopy of the hybrid star HD 49434. The results showalmost no consistency between the frequencies found using the two techniques and no characteristic period spacings or couplings were identified in either data set. The spectroscopic data additionally show no evidence for any long-term (5 yr) variation in the dominant frequency. The 31 spectroscopic frequencies identified have standard deviation profiles suggesting multiple modes sharing (l, m) in the δ Scuti frequency region and several skewed modes sharing the same (l, m) in the γ Doradus frequency region. In addition, there is a clear frequency in the γ Doradus frequency region that appears to be unrelated to the others. We conclude HD 49434 remains a δ Scuti/γ Doradus candidate hybrid star but more sophisticated models dealingwith rotation are sought to obtain a clear picture of the pulsational behaviour of this star.

Description
Citation
Brunsden, E., Pollard, K.R., Cottrell, P.L, Uytterhoeven, K., Wright, D.J., De Cat, P. (2015) The classification of frequencies in the gamma Doradus/delta Scuti hybrid star HD 49434. Monthly Notices of the Royal Astronomical Society,, 447, pp. 2970-2980.
Keywords
line: profiles, techniques: spectroscopic, stars: individual: HD 49434, stars: oscillations, stars: variables: general
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Fields of Research::51 - Physical sciences::5101 - Astronomical sciences::510109 - Stellar astronomy and planetary systems
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