NOAO >   Observing Info >   Approved Programs >   2017B-0092

Small NOAO Logo

Program Information for 2017B-0092


PI: Judith Provencal, U. of Delaware, jlp@udel.edu
Address: Department of Physics and Astronomy, Sharp Laboratory, Newark, Delaware 19176 USA

CoI: D L Holdsworth, University of Central Lancashire
CoI: Hideyuki Saio, Tohoku University
CoI: Donald W Kurtz, University of Central Lancashire

Title: Asteroseismology of a roAp star: A new pulsation mechanism at work?

Abstract: The rapidly oscillating Ap (roAp) stars are a rare subset of chemically peculiar, magnetic Ap stars. These pulsators are the only group of main-sequence classical pulsators known to exhibit high radial order p-mode pulsations. HD,42659 was an early addition to the small family of roAp stars. This star shows a single pulsation frequency, which cannot be explained by current theory. Recently, the analysis of roAp stars with Kepler/K2 and Whole Earth Telescope data has identified a subgroup of stars which all show single, quadrupole, pulsation modes with unexpected phase variations and frequencies much greater than theoretically expected. Those stars lie in the same region in a $nu L/M - T_{rm eff}$ diagram. HD,42659 also lies in this region. As such we are organising an international Whole Earth Telescope campaign with HD,42659 as the primary target. With the high duty-cycle light curve that we will obtain, we will test the pulsation driving mechanism in this star. Currently, the pulsations in roAp stars are thought to be driven by the $kappa$-mechanism acting in the H-ionization zone, with some driving from turbulent pressure. However, these methods cannot explain the high frequencies seen in this subset of roAp stars. The results from this proposal will test current theory, with the aim of uncovering the true driving mechanism in these stars through extensive theoretical modelling. Our proposed SMARTS 0.9-m observations will play a key role advancing the understanding of roAp stars.

Program Type: Standard/Galactic

Scheduled Nights:
Run 2 (2017B):  CT-1.3m/ANDI -- 28hrs


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2017B-0092

noaoprop-help@noao.edu

Small NOAO Logo