The Solar Activity Cycle & Kepler – FDL 202

Intro presentation to the FDL 2020 Heliophysics/Starspots challenge.

Transcript

1. The Solar Activity Cycle & Kepler Brett Morris FDL Heliophysics/Starspots Introduction June 11, 2020 1
2. 2 Hinode's Solar Optical Telescope
3. 2 Hinode's Solar Optical Telescope
4. March 9, 1916 Spot image Spectra Zeeman splitting 3 George Hale
5. Sir John Larmor (1919) March 9, 1916 Spot image Spectra Zeeman splitting 3 George Hale
6. NASA/SDO 4 Solar Cycle: Active latitudes Howard et al. (1984), Morris et al. (2017)
7. NASA/SDO 4 Solar Cycle: Active latitudes Howard et al. (1984), Morris et al. (2017)
8. NASA/SDO 4 Solar Cycle: Active latitudes Spot latitude [deg] Howard et al. (1984), Morris et al. (2017) 15° -15°
9. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 Solar Cycle: Butterfly diagram
10. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 • 11 year period Solar Cycle: Butterfly diagram
11. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 • 11 year period • Spots begin to appear near 30° Solar Cycle: Butterfly diagram
12. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 • 11 year period • Spots begin to appear near 30° • Active latitudes drift towards equator Solar Cycle: Butterfly diagram
13. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 • 11 year period • Spots begin to appear near 30° • Active latitudes drift towards equator • Spots near 15° at spot number maximum Solar Cycle: Butterfly diagram
14. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 5 • 11 year period • Spots begin to appear near 30° • Active latitudes drift towards equator • Spots near 15° at spot number maximum • No spots during activity minimum Solar Cycle: Butterfly diagram
15. 6 Solar Cycle: Bipolar magnetic regions NASA/SDO, 304 Angstrom
16. 6 Solar Cycle: Bipolar magnetic regions • Big spots come in pairs, called “bipolar magnetic regions” NASA/SDO, 304 Angstrom
17. 6 Solar Cycle: Bipolar magnetic regions • Big spots come in pairs, called “bipolar magnetic regions” • Spots in pair have opposite polarity – toroidal field NASA/SDO, 304 Angstrom “Leading” “Following”
18. 6 Solar Cycle: Bipolar magnetic regions • Big spots come in pairs, called “bipolar magnetic regions” • Spots in pair have opposite polarity – toroidal field • Spots aligned nearly east-west, with a tilt NASA/SDO, 304 Angstrom “Leading” “Following”
19. 6 Solar Cycle: Bipolar magnetic regions • Big spots come in pairs, called “bipolar magnetic regions” • Spots in pair have opposite polarity – toroidal field • Spots aligned nearly east-west, with a tilt • Field strength greater in leading component NASA/SDO, 304 Angstrom Leading Following
20. 7 Solar Interior Convective zone: circulation, turbulence Radiative zone: stably stratified NASA MSFC
21. Physics of the Solar Dynamo and Solar Cycle Big Questions: – What plasma motions can produce long-lived magnetic activity? – How does the magnetic energy oscillate between two components? – poloidal: dipolar field near polar caps – toroidal: spots at active latitudes 8
22. Physics of the Solar Dynamo and Solar Cycle Big Questions: – What plasma motions can produce long-lived magnetic activity? – How does the magnetic energy oscillate between two components? – poloidal: dipolar field near polar caps – toroidal: spots at active latitudes 8 Poloidal Toroidal
23. 9 Frozen flux theorem Frozen flux (Alfvén’s) theorem: Bulk flow of the plasma moves fields lines with it. Rm 1
24. 9 Frozen flux theorem Frozen flux (Alfvén’s) theorem: Bulk flow of the plasma moves fields lines with it. Rm 1 ~ B ~ B Implication: stretching a volume of fluid with a frozen-in B-field amplifies field strength
25. 10 ~ B Babcock (1969) Poloidal B-field + Differential Rotation
26. 10 Differential rotation: equator rotates faster than poles ~ B Babcock (1969) ~ v Poloidal B-field + Differential Rotation
27. 10 Differential rotation: equator rotates faster than poles ~ B Babcock (1969) ~ v Poloidal B-field + Differential Rotation
28. 11 ~ B Babcock (1969) …after two turns Poloidal B-field + Differential Rotation
29. 12 ~ B Babcock (1969) …after many turns Poloidal B-field + Differential Rotation
30. 13 Ω-effect: Field lines stretched, orientation is toroidal, and field amplified ~ B ~ B Babcock (1969) ~ B Poloidal B-field + Differential Rotation = Toroidal Field Poloidal Toroidal
31. 13 Ω-effect: Field lines stretched, orientation is toroidal, and field amplified ~ B ~ B Babcock (1969) How does the amplified field affect the flux tubes? ~ B Poloidal B-field + Differential Rotation = Toroidal Field Poloidal Toroidal
32. 14 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spots = intersections of flux tubes and photosphere ~ F buoy
33. 14 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spots = intersections of flux tubes and photosphere ~ F buoy Biermann (1941) Spots appear where convection inhibited by B-field Big Bear Solar Observatory
34. 15 Babcock (1969) Spot latitudes trace B-field amplification sin = ± 1.5 n + 3 Latitude ϕ of max B-field after n turns:
35. 15 Babcock (1969) Spot latitudes trace B-field amplification Time Spot Latitude [deg] sin = ± 1.5 n + 3 Latitude ϕ of max B-field after n turns:
36. Spot latitude [deg] Years Howard et al. (1984), Morris et al. (2017) 16 • Spots begin to appear near 30° • Active latitudes drift towards equator • Spots near 15° at spot number maximum Spot latitudes trace B-field amplification
37. 17 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spot bipolarity arises naturally May 31, 2017 NASA/SDO 171nm, Magnetogram ~ F buoy
38. 17 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spot bipolarity arises naturally May 31, 2017 NASA/SDO 171nm, Magnetogram ~ F buoy
39. 17 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spot bipolarity arises naturally May 31, 2017 NASA/SDO 171nm, Magnetogram ⌦ ~ B “Hale’s Law” ~ F buoy
40. 17 ~ Bint ~ B ext Photosphere Bipolar magnetic regions Babcock (1969) Spot bipolarity arises naturally May 31, 2017 NASA/SDO 171nm, Magnetogram ⌦ ~ B ~ F buoy
41. 18 BMR tilt arises from Coriolis effect ⌦ ~ B “Joy’s Law” Wang & Shelley (1991)
42. 18 BMR tilt arises from Coriolis effect ⌦ ~ B “Joy’s Law” Wang & Shelley (1991)
43. 19 Babcock (1969) Ω Ω-effect: Poloidal → Toroidal field Poloidal Toroidal
44. If flux tubes are near surface: • Too much stretching • Too much buoyancy α α-effect: Two Problems
45. 21 Helioseismology saves the α-effect Howe et al. (2000) NASA/Goddard Space Flight Center Scientific Visualization Studio, the SDO Science Team, and the Virtual Solar Observatory
46. 21 Helioseismology saves the α-effect Howe et al. (2000) NASA/Goddard Space Flight Center Scientific Visualization Studio, the SDO Science Team, and the Virtual Solar Observatory
47. 22 r/R ⌦/2⇡ [nHz] Rotation Frequency Radiative Convective Howe et al. (2000) 25 d 27 d 30 d 31 d Rotation Period Helioseismology saves the α-effect
48. 22 r/R ⌦/2⇡ [nHz] Rotation Frequency Radiative Convective Howe et al. (2000) 25 d 27 d 30 d 31 d Rotation Period Helioseismology saves the α-effect “Tachocline”
49. 22 r/R ⌦/2⇡ [nHz] Rotation Frequency Radiative Convective Howe et al. (2000) 25 d 27 d 30 d 31 d Rotation Period Helioseismology saves the α-effect “Tachocline”
50. 23 NASA Goddard Space Flight Center
51. 23 NASA Goddard Space Flight Center
52. 24 Why is the period 11 years? Physics of the Solar Dynamo and Solar Cycle
53. 25 Solar bulk flow NASA SOHO Michelson Doppler Imager (MDI)
54. 25 Solar bulk flow NASA SOHO Michelson Doppler Imager (MDI) From conservation of mass: ~10 m/s at surface = 1 m/s at base of convection zone
55. Rsun 30° s v=1m/s 25 Solar bulk flow NASA SOHO Michelson Doppler Imager (MDI) From conservation of mass: ~10 m/s at surface = 1 m/s at base of convection zone Time to pass from 30° latitude to the equator: ⌧ ⇡ s v ⇡ R ✓ v ⇡ R ⇡/6 1 m s 1 ⇡ 11 yr
56. Rsun 30° s v=1m/s 25 Solar bulk flow NASA SOHO Michelson Doppler Imager (MDI) From conservation of mass: ~10 m/s at surface = 1 m/s at base of convection zone Time to pass from 30° latitude to the equator: ⌧ ⇡ s v ⇡ R ✓ v ⇡ R ⇡/6 1 m s 1 ⇡ 11 yr ⌧ ⇡ s v ⇡ R ✓ v ⇡ R ⇡/6 1 m s 1 ⇡ 11 yr
57. Rsun 30° s v=1m/s 25 Solar bulk flow NASA SOHO Michelson Doppler Imager (MDI) From conservation of mass: ~10 m/s at surface = 1 m/s at base of convection zone Time to pass from 30° latitude to the equator: ⌧ ⇡ s v ⇡ R ✓ v ⇡ R ⇡/6 1 m s 1 ⇡ 11 yr ⌧ ⇡ s v ⇡ R ✓ v ⇡ R ⇡/6 1 m s 1 ⇡ 11 yr
58. NASA’s Kepler: 2341 planets 2418 planet candidates Credit: NASA
59. Credit: NASA, Ethan Kruse
60. Credit: NASA, Ethan Kruse
61. Blue: Previously discovered Red: Discovered by Kepler Orange: Big 2014 multi-planet systems release
62. Blue: Previously discovered Red: Discovered by Kepler Orange: Big 2014 multi-planet systems release
63. 29 Time Flux Exoplanet Transits
64. 30 Kepler-62: stellar rotation
65. 30 Kepler-62: stellar rotation
66. 31 Kepler-62: stellar rotation
67. 32 Kepler-452: stellar rotation
68. 33 Kepler: stellar rotation Data Fit
69. 34 Kepler: stellar rotation Data Fit
70. Misaligned exoplanets reveal active latitudes • Timing encodes active latitude positions • Amplitude encodes spot contrast 35 NASA/SDO/HMI
71. Misaligned exoplanets reveal active latitudes • Timing encodes active latitude positions • Amplitude encodes spot contrast 35 NASA/SDO/HMI
72. Misaligned exoplanets reveal active latitudes • Timing encodes active latitude positions • Amplitude encodes spot contrast 35 NASA/SDO/HMI
73. 36 HAT-P-11: Sun-like active latitudes Morris et al. 2017a STSP • STSP: forward model for starspot occultations
74. 36 HAT-P-11: Sun-like active latitudes Morris et al. 2017a STSP • STSP: forward model for starspot occultations
75. 37 HAT-P-11: Sun-like active latitudes Morris et al. 2017a Posterior Samples STSP • XSEDE/Open Science Grid: 740,000 core hours
76. 38 HAT-P-11: Sun-like active latitudes • Active latitudes: similar positions, widths to Sun’s Morris et al. 2017a