Open AccessOn the dipolar f mode of stellar oscillation
Author(s) -
ChristensenDalsgaard J.,
Gough D.O.
Publication year - 2001
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 - 10.1046/j.1365-8711.2001.04654.x
Subject(s) - physics , oscillation (cell signaling) , perturbation (astronomy) , dipole , adiabatic process , mode (computer interface) , astrophysics , asteroseismology , classical mechanics , computational physics , stars , astronomy , quantum mechanics , biology , operating system , genetics , computer science
The classification of adiabatic modes of non‐radial stellar oscillation was established by Cowling in 1941. In addition to acoustic and gravity modes he identified an intermediate mode, which he labelled the f mode, and which in simple stellar models has no radial node. The motion of a dipolar f mode (of spherical‐harmonic degree l=1) shifts the centre of mass, and must have zero frequency. On the other hand, if the perturbation to the gravitational potential is neglected (the case considered by Cowling) the f mode has a frequency intermediate between those of the gravity and acoustic modes; this is true of modes of any degree (l≥1) . Here we consider the properties of the dipolar f mode, elucidating the origin of these differences through continuous transformations between the various relevant cases; in addition, we discuss the broader issues of the classification of modes of non‐radial oscillation.