1. Kuhn - HMI Science Interests: Limb photometry and astrometry
HMI, with 4Kx4K (or even 2Kx2K) pixel resolution will improve limb astrometry and photometry in some respects by over an order of magnitude
HMI roll calibration and lessons learned from MDI thermal environment may do better than an order of magnitude improvement in some astrometric goals
HMI Team 4/30/03

2. Focus areas Limb Astrometry Limb brightness
rotational constraints through limb harmonics
secular radius variations
limb seismology (low frequency modes)
Limb brightness
thermal magnetic diagnostics
limb seismology
HMI Team 4/30/03

3. Limb astrometry dr
Angle of arrival fluctuations define dr dI
Photometric gain uncertainty (flatfielding) defines dr
In practice limb isn’t knife edge, spacecraft pointing jitter is about 0.01 pixel,
long term stability limitations are due to optics and thermal drifts [1px=2”]
HMI Team 4/30/03

4. Shape, rotation, and gravitational figure
(-1)
(10)
(50)
HMI Team 4/30/03

5. Shape and gravitational potential
HMI Team 4/30/03

6. Emilio et al.: No W measured -- limits only
Bush et al sees different “temperature”
trend after SoHO vacation.
HMI Team 4/30/03

7. Interpreting solar radius change
< 0.02
HMI Team 4/30/03

8. Oscillations: astrometry vs. Doppler measurements, random telegraph
f=16
HMI Team 4/30/03

9. Astrometric advantages
HMI Team 4/30/03

10. P-mode limb oscillations
P-mode 5min limb
shape oscillations
15cm/s microarcsec
HMI Team 4/30/03

11. G-modes in velocity and displacement
1600 days of MDI astrometry (l=6)
Appourchaux et al. (2000)
HMI Team 4/30/03

12. Low frequency oscillations
HMI Team 4/30/03

13. Another branch of the solar dispersion relation: r-modes
100m x 90,000km
HMI Team 4/30/03

14. Antishadows
HMI Team 4/30/03

15. Focus areas Limb Astrometry Limb brightness
rotational constraints through limb harmonics
secular radius variations
limb seismology (low frequency modes)
Limb brightness
thermal magnetic diagnostics
limb seismology
HMI Team 4/30/03