17
Helioseismology and the Solar Cycle - Rachel Howe - 2006 Mads L. Severinsen, Kristian Jerslev & Lars V. T. Occhionero - d. 18. Maj 2010

Helioseismology and the solar cycle

Embed Size (px)

DESCRIPTION

A talk during a course on the physics of the Sun, about helioseismology and parameters measured using this technique. Quite technical

Citation preview

Page 1: Helioseismology and the solar cycle

Helioseismology and the Solar Cycle- Rachel Howe - 2006

Mads L. Severinsen, Kristian Jerslev & Lars V. T. Occhionero- d. 18. Maj 2010

Page 2: Helioseismology and the solar cycle

Introduktion

Direct observations of Solar Activity → From Photosphere

Activity originates from within the Convective Zone

Measure of solar interior → Helioseismology

Page 3: Helioseismology and the solar cycle

Helioseismology 101

Sun oscillates in Spherical Harmonic Oscillations

Y lm ,=−1mc lmP l

mcosei m

Page 4: Helioseismology and the solar cycle

Helioseismology 101

l = 1, m = 0 l = 10, m = 5

Page 5: Helioseismology and the solar cycle

Helioseismology 101

l = 0 l = 2 l = 20 l = 25 l = 75

Page 6: Helioseismology and the solar cycle

Helioseismology 101

gravity modes Surface gravity

modes pressure modes

(acoustic)

Page 7: Helioseismology and the solar cycle

Article Data

Sun as a Star l < 4 Whole Sun

Medium Degree l < 300 10''

High Degree l > 200 Very Local

Page 8: Helioseismology and the solar cycle

Article Data

Page 9: Helioseismology and the solar cycle

Changes in interior dynamics- Torsional oscillation change

Page 10: Helioseismology and the solar cycle

Changes in interior dynamics- Phase and amplitude changes

Observations Changes in torsional

oscillation during period Possible changes all way

through convection zone Zonal flows: constrains

dynamo models Changes in meridional

flow oserved through high l oscillations

Page 11: Helioseismology and the solar cycle

Changes in mode-parameters- Frequency shifts

Page 12: Helioseismology and the solar cycle

Changes in mode-parameters- Frequency shifts

Page 13: Helioseismology and the solar cycle

Changes in mode-parameters- Mechanisms

Clear change in frequency as function of activity and time

No clear mechanism

Not only a magnetic effect

Page 14: Helioseismology and the solar cycle

Changes in mode-parameters- Amplitude and Width

Page 15: Helioseismology and the solar cycle

Changes in mode-parameters- Width and Amplitude

Results:

Damping due to surface activity Width and amplitude inversly related to lifetime

Page 16: Helioseismology and the solar cycle

Subsurface structural changes

Subsurface changes still unknown– High l-modes drown in surface variations

– High l-modes hard to observe

Better results with SDO ?

We can only see the outermost part of surface (R=99%)

Page 17: Helioseismology and the solar cycle

Conclusion

Chance to look into the Sun's Convection zone Gives experimental data to dynamo-model

confinement See changes in the suns hydrodynamics during

cycles