**Solar 3D Power Spectrum**

### Summary of Solar 3D Power Spectrum

The power spectrum here represents *p*-mode freqency
oscillations of the
Sun. The *x* and *y* axes are wave numbers which are
calculated from the degree *l* of the spherical surface harmonic
modes. The *z* axis is the frequency of oscillation.
For solar oscillations, the power is not evenly distributed in the k-omega
plane, but instead corresponds to *ridges*. Each of these ridges
corresponds to a fixed number of wave nodes in the radial direction. The
ridges are seen here as "rays" in the cut planes facing you.

The rings that you see cut out of the *z*-axis plane are 3D
representations of the *p*-mode ridges. Six rings equal six
modes. Eight rings equal eight *p*-modes, and so on. The frequency
value of the top of the *z* plane is the Nyquist frequency, the
high-frequency limit given by the time resolution of the signal, which
here is 8334 microHz. The densest part of the ridge pattern is
roughly 3000 microHz. The frequency resolution is 5.71 microHz.

This data was acquired by the
Michelson Doppler Imager instrument on
board the
SOHO spacecraft in June 1996. Data and guidance: Phil
Scherrer, Rick Bogart, Jesper Schou, Sasha Kosovichev, and Tom
Duvall. The 3D power spectrum data set was generated by Rick Bogart,
prepared by Amara Graps into this 3D representation, and presented by
Rick Bogart at the "Sounding Solar and Stellar Interiors, IAU
Symposium No. 181," Nice, France, 30 September -- 3 October, 1996.

### One slice through the frequency plane.

You can also download a postscript
version of the above figure.

### Two slices through the frequency plane.

**SOHO SOI/MDI Results.**

**The SOI Main Page.**

Last Modified by Amara Graps,
SOI, on 07 January 1997.