Katlenburg-Lindau, February 7, 2012

Transcription

1 SUN S MAGNETIC POLE Judith de Patoul, Bernd Inhester and Robert Cameron MPS Solar Group Seminar Katlenburg-Lindau, February 7, 2012

2 MAGNETIC POLE On the Earth: The magnetic pole is the point where the large scale field is perpendicular to the surface. Earth s magnetic pole. On the Sun: Can we define such a point on the Sun? Can we measure its location? Which information can it provide us? Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 2

3 SOLAR POLAR PLUMES Solar plumes trace the field lines We can use them to find the location of the solar magnetic pole. STEREO/EUVI 171Å 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 3

4 OUTLINE 1 Observation of the temporal evolution of the 3D axis of plume. 2 Identification of the Sun s magnetic pole. 3 Comparison of the observations with an open magnetic flux model. 4 Dicussion: What can we learn from this? Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 4

5 SOHO/EIT AND STEREO/EUVI A&B Data from 1st of April 2007 to 31st of May 2008 Positions of the Earth, STEREO A & B Wavelength: 171Å Pixel resolution: STEREO/EUVI: 1.6 arcsec/pixel SOHO/EIT: 2.5 arcsec/pixel Separation angles: EUVI-A & EUVI-B: EUVI-B & EIT: EUVI-A & EIT: st of May 2008 Preprocessing: secchi_prep.pro eit_prep.pro Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 5

6 OBSERVATION STEREO/EUVI-A (171 Å) on 1-Nov-2007 at 00:06:00 UT Cosmic ray hits removal + Contrast enhancement Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 6

7 IDENTIFICATION OF THE MAGNETIC POLE Hough-wavelet Transform: HW(ρ, a, θ) = I(x) R 2 1 ( u θ x ρ ) a ψmh dx, a where θ [ π/2, π/2[, u θ = (cos θ sin θ), ρ [ ρ max, ρ max], and a R + 0 Image Space (x, y) Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 7

8 IDENTIFICATION OF THE MAGNETIC POLE Hough-wavelet Transform: HW(ρ, a, θ) = I(x) R 2 1 ( u θ x ρ ) a ψmh dx, a where θ [ π/2, π/2[, u θ = (cos θ sin θ), ρ [ ρ max, ρ max], and a R + 0 Image Space (x, y) Hough-wavelet Space (ρ, a = 1.0, θ) = Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 7

9 IDENTIFICATION OF THE MAGNETIC POLE Hough-wavelet Transform: HW(ρ, a, θ) = I(x) R 2 1 ( u θ x ρ ) a ψmh dx, a where θ [ π/2, π/2[, u θ = (cos θ sin θ), ρ [ ρ max, ρ max], and a R + 0 Image Space (x, y) Hough-wavelet Space (ρ, a = 5.5, θ) = Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 7

10 IDENTIFICATION OF THE MAGNETIC POLE Hough-wavelet Transform: HW(ρ, a, θ) = I(x) R 2 1 ( u θ x ρ ) a ψmh dx, a where θ [ π/2, π/2[, u θ = (cos θ sin θ), ρ [ ρ max, ρ max], and a R + 0 Image Space (x, y) Hough-wavelet Space (ρ, a = 14.5, θ) = Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 7

11 HOUGH-WAVELET TRANSFORM: SOLAR PLUMES 1. Image Space (x, y) 2. Mapping in (s r, s φ )-coordinate (x, y) (r, φ) { r = x2 + y 2 φ = arctan (x/y) (r, φ) (s r, s φ ) { sr = (r r c)/ r s φ = φ/ φ 3. Hough-wavelet Space (ρ, a, θ) 4. Hough Space (ρ, a M, θ) Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 8

12 HOUGH-WAVELET TRANSFORM: RESULTS Pre-processed Image: Hough Space (ρ, a M, θ): (J. de Patoul et al., 2011) Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 9

13 MAGNETIC POLE & MAGNETIC OPENING plume peaks are aligned along an inclined line θ = u ρ + v Magnetic Opening Variation of the slope u: u 0 u > 0 after 45 u >> 0 after 90 Magnetic Pole location Variation of the intercept v/u: v/u < 0 v/u = 0 after 90 v/u > 0 after 180 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 10

14 MAGNETIC OPENING SLOPE u North pole: EUVI-B EIT EUVI-A Slope u 0 Slope u > 0 Slope u Slope u South pole: EUVI-B EIT EUVI-A Slope u >> 0 Data from 1st of April 2007 to 31st of May 2008 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 11

15 MAGNETIC POLE INTERCEPT v/u intercept v/u < 0 intercept v/u = 0 intercept u/v intercept u/v North pole: South pole: EUVI-B EIT EUVI-A EUVI-B EIT EUVI-A Colatitude Colatitude intercept v/u > 0 Data from 1st of April 2007 to 31st of May 2008 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 12

16 SUN S OPEN MAGNETIC FLUX MODEL From to (Sun s open magnetic flux and the heliospheric current sheet: Robert Cameron et al. ; J. Jiang, R. Cameron et al., 2010) Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 13

17 MAPPING ONTO THE NORTH POLE From to Open and closed (white/black) field lines: Field line inclinations: arctan (B θ /B r): Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 14

18 SYNTHETIC PLUME CONSTRUCTION For each rotation angle, we produce synthetic plumes: Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 15

19 SYNTHETIC PLUME RECONSTRUCTION = See movie Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 16

20 MAGNETIC POLE & MAGNETIC OPENING IDENTIFICATION Pre-processed Image: Hough Space (ρ, a M, θ): Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 17

21 MAGNETIC OPENING SLOPE u Model North pole: Slope u 0 Slope u > 0 Slope u Slope u Observation North pole: EUVI-B EIT EUVI-A Slope u >> 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 18

22 MAGNETIC POLE INTERCEPT v/u Model North pole: intercept v/u < 0 intercept v/u = 0 intercept u/v intercept u/v Observation North pole: EUVI-B EIT EUVI-A Colatitude Colatitude intercept v/u > 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 19

23 MAGNETIC POLE INTERCEPT v/u Model North pole: intercept v/u < 0 intercept u/v Colatitude intercept v/u = 0 Radial field: intercept v/u > 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 20

24 DISCUSSION We have identified: the solar magnetic pole s location. the magnetic field opening at the pole. What can we infer from the variation of these quatities? Tells us whether there is a flux emergence on (the back side of) the Sun. Can comment on the expantion factor of the field lines. Gives us a better constraint on the near polar meridional flows. Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 21

25 THANK YOU!

26 MAGNETIC OPENING SLOPE u Model South pole: Slope u 0 Slope u > 0 Slope u Slope u Observation South pole: EUVI-B EIT EUVI-A Slope u >> 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 23

27 MAGNETIC POLE INTERCEPT v/u Model South pole: intercept v/u < 0 intercept v/u = 0 intercept u/v intercept u/v Observation South pole: EUVI-B EIT EUVI-A Colatitude Colatitude intercept v/u > 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 24

28 MAGNETIC POLE INTERCEPT v/u Model South pole: intercept v/u < 0 intercept u/v Colatitude intercept v/u = 0 Radial field: intercept v/u > 0 Data from 21st of October 2007 to 18th of November 2007 Judith de Patoul et al. Katlenburg-Lindau, 2011 SUN S MAGNETIC POLE 25