FANNING OUT OF THE SOLAR f-MODE IN THE PRESENCE OF NON-UNIFORM MAGNETIC FIELDS?

Journal Article · Sat Nov 01 04:00:00 EDT 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/795/1/L8· OSTI ID:22364920

Singh, Nishant K.; Brandenburg, Axel ^[1]; Rheinhardt, Matthias ^[2]

---

1. Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)
2. Physics Department, Gustaf Hällströmin katu 2a, PO Box 64, FI-00014 University of Helsinki, Helsinki (Finland)

We show that in the presence of a magnetic field that is varying harmonically in space, the fundamental mode, or f-mode, in a stratified layer is altered in such a way that it fans out in the diagnostic kω diagram, with mode power also within the fan. In our simulations, the surface is defined by a temperature and density jump in a piecewise isothermal layer. Unlike our previous work (Singh et al. 2014), where a uniform magnetic field was considered, here we employ a non-uniform magnetic field together with hydromagnetic turbulence at length scales much smaller than those of the magnetic field. The expansion of the f-mode is stronger for fields confined to the layer below the surface. In some of those cases, the kω diagram also reveals a new class of low-frequency vertical stripes at multiples of twice the horizontal wavenumber of the background magnetic field. We argue that the study of the f-mode expansion might be a new and sensitive tool to determine subsurface magnetic fields with azimuthal or other horizontal periodicity.

• OSTI ID: 22364920
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 795; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLOWERS
COMPUTERIZED SIMULATION
DENSITY
DIAGRAMS
EXPANSION
LAYERS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
PERIODICITY
SPACE
SUN
SURFACES
TURBULENCE