Polar Faculae Magnetism

Transcription

1 Polar Faculae Magnetism Adur Pastor Yabar [1,2] María Jesús Martínez González [1,2] Manuel Collados Vera [1,2] [1] Instituto de Astrofísica de Canarias [2] Universidad de La Laguna Polarimetry: From the Sun to Stars and Stellar Environments; IAU Symposium 305; 3rd December

2 Outline What we know from Magnetograms What we know from Spectropolarimetric Analysis Where We Are Conclusions Adur Pastor Yabar; IAU Symposium 305; 3rd December

3 WHAT WE KNOW FROM MAGNETOGRAMS Adur Pastor Yabar; IAU Symposium 305; 3rd December

4 Bibliography Babcock & Babcock 1955 Sheeley 1964 Severny et al Svalgaard et al Okunev & Kneer 2004 Blanco Rodríguez et al Adur Pastor Yabar; IAU Symposium 305; 3rd December

5 Magnetograms: Polar Scenario Polar magnetism characterized by: Not null net flux over the polar cap Opposite signs at both poles Babcock & Babcock 1955 Adur Pastor Yabar; IAU Symposium 305; 3rd December

6 Magnetograms: Polar Scenario Polar magnetism characterized by: Not null net flux over the polar cap Opposite signs at both poles Polarity inversion shifted a quarter of the cycle compared to activity belt

7 Blanco Rodríguez et al Magnetograms: Polar Scenario Polar magnetism characterized by: Not null net flux over the polar cap Opposite signs at both poles Polarity inversion shifted a quarter of the cycle compared to activity belt Magnetic flux concentrated in small structures (Facula) Polar Facula with both LOS signs (70/80%-30/20%) Adur Pastor Yabar; IAU Symposium 305; 3rd December

8 Magnetograms: Polar Scenario What kind of local magnetic field configuration gives: Tests: -polar cap region with net sign -mix (80%/20%) LOS magnetogram? We consider several magnetic field configurations in the normal to the Sun's surface reference system and construct the LOS magnetogram Adur Pastor Yabar; IAU Symposium 305; 3rd December

9 Magnetograms: Polar Scenario σ n in /n out Negative flux [%] latitude [75º-90º] Isotropic Half-Isotropic / / / / / / From magnetograms one can not determine the net flux through the surface of the polar cap

10 WHAT WE KNOW FROM SPECTROPOLARIMETRIC ANALYSIS Adur Pastor Yabar; IAU Symposium 305; 3rd December

11 Bibliography Tsuneta et al Blanco Rodríguez et al Ito et al Shiota et al Adur Pastor Yabar; IAU Symposium 305; 3rd December

12 Ambiguity problem

13 Ambiguity problem Ito et al Shiota et al. 2012

14 Ito et al Ambiguity problem Ito et al Shiota et al. 2012

15 Ito et al Ambiguity problem Vertical Undetermined Horizontal 0º-40º ; 140º-180º 40º-70º ; 110º-140º 70º-110º Ito et al Shiota et al. 2012

16 Ito et al Ambiguity problem Solut. 1 Vertical Vertical Horizontal Vertical Undetermined Horizontal Ito et al Shiota et al Solut 2. Vertical Undetermined Undetermined Horizontal Undetermined Horizontal Final Solution Most Vertical Vertical Horizontal Undetermined Undetermined Undetermined?

17 Problems with this method A particular configuration is imposed Undetermined magnetic fields are not studied It is more or less accurate statistically but not in a one to one comparison Adur Pastor Yabar; IAU Symposium 305; 3rd December

18 Problems with this method A particular configuration is imposed Undetermined magnetic fields are not studied It is more or less accurate statistically but not in a one to one comparison

19 Problems with this method A particular configuration is imposed Undetermined magnetic fields are not studied It is more or less accurate statistically but not in a one to one comparison

20 WHERE WE ARE Adur Pastor Yabar; IAU Symposium 305; 3rd December

21 Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Adur Pastor Yabar; IAU Symposium 305; 3rd December

22 South Pole Stokes I Where We Are Data From SST (La Palma, Spain) in 6173Å FeI

23 Stokes Q Where We Are Data From SST (La Palma, Spain) in 6173Å FeI South Pole

24 Stokes U Where We Are Data From SST (La Palma, Spain) in 6173Å FeI South Pole

25 Stokes V Where We Are Data From SST (La Palma, Spain) in 6173Å FeI South Pole

26 Where We Are Data from SST (La Palma, Spain) in 6173Å FeI We have performed Inversions using SIR (Ruíz Cobo and del Toro Iniesta 1992) Adur Pastor Yabar; IAU Symposium 305; 3rd December

27 Magnetic Field Intensity Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole

28 Magnetic Field Inclination Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole

29 Magnetic Field Azimuth Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole

30 Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done Ambiguity solution: First attempts We impose an equally probable azimuth in local reference frame Adur Pastor Yabar; IAU Symposium 305; 3rd December

31 Where We Are Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done Ambiguity solution: First attempts We Impose An Equally Probable Azimuth in Local Reference Frame

32 CONCLUSION Adur Pastor Yabar; IAU Symposium 305; 3rd December

33 Conclusions A unipolar local magnetic configuration can easily give a mix LOS magnetogram at high latitudes (above 60º) Transformation from LOS magnetic configuration to Local is not direct!! If radial configuration is assumed this step becomes direct but also not accurate If LOS magnetograms are dominated by one sign, a magnetic polarity is dominant in the polar cap but it is not possible to know how much There is not yet a correct azimuth disambiguation method for polar magnetic fields

34 THANKS!