Testing excitation models of rapidly oscillating Ap stars with interferometry

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Cunha, MS (Author) FCUP; Alentiev, D (Author) Other; Brandao, IM (Author) Other; Perraut, K (Author) Other

Journal

Title: Monthly Notices of the Royal Astronomical Society

Vol. 436

Pages: 1639-1647

ISSN: 0035-8711

Publisher: Oxford University Press

Indexing

ISI Web of Knowledge - 28 Citations

Scopus - 30 Citations

Other information

Authenticus ID: P-008-HA3

DOI: 10.1093/mnras/stt1679

Abstract (EN): Rapidly oscillating Ap stars are unique objects in the potential they offer to study the interplay between a number of important physical phenomena, in particular, pulsations, magnetic fields, diffusion and convection. Nevertheless, the simple understanding of how the observed pulsations are excited in these stars is still in progress. In this work, we perform a test to what is possibly the most widely accepted excitation theory for this class of stellar pulsators. The test is based on the study of a subset of members of this class for which stringent data on the fundamental parameters are available thanks to interferometry. For three out of the four stars considered in this study, we find that linear, non-adiabatic models with envelope convection suppressed around the magnetic poles can reproduce well the frequency region where oscillations are observed. For the fourth star in our sample no agreement is found, indicating that a new excitation mechanism must be considered. For the three stars whose observed frequencies can be explained by the excitation models under discussion, we derive the minimum angular extent of the region where convection must be suppressed. Finally, we find that the frequency regions where modes are expected to be excited in these models are very sensitive to the stellar radius. This opens the interesting possibility of determining this quantity and related ones, such as the effective temperature or luminosity, from comparison between model predictions and observations, in other targets for which these parameters are not well determined.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9