Polar Faculae Magnetism Adur Pastor Yabar [1,2] (apastor@iac.es) 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
Outline What we know from Magnetograms What we know from Spectropolarimetric Analysis Where We Are Conclusions Adur Pastor Yabar; IAU Symposium 305; 3rd December
WHAT WE KNOW FROM MAGNETOGRAMS Adur Pastor Yabar; IAU Symposium 305; 3rd December
Bibliography Babcock & Babcock 1955 Sheeley 1964 Severny et al. 1971 Svalgaard et al. 1978 Okunev & Kneer 2004 Blanco Rodríguez et al. 2007 Adur Pastor Yabar; IAU Symposium 305; 3rd December
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
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 http://solarscience.msfc.nasa.gov/dynamo.shtml
Blanco Rodríguez et al. 2007 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
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
Magnetograms: Polar Scenario σ n in /n out Negative flux [%] latitude [75º-90º] Isotropic - 50.03 Half-Isotropic - 43.51 10 0/1 9.1 30 0/1 29.34 10 1/2 28.82 10 1/3 35.25 10 1/5 22.24 30 1/5 35.99 From magnetograms one can not determine the net flux through the surface of the polar cap
WHAT WE KNOW FROM SPECTROPOLARIMETRIC ANALYSIS Adur Pastor Yabar; IAU Symposium 305; 3rd December
Bibliography Tsuneta et al. 2008 Blanco Rodríguez et al. 2010 Ito et al. 2010 Shiota et al. 2012 Adur Pastor Yabar; IAU Symposium 305; 3rd December
Ambiguity problem
Ambiguity problem Ito et al. 2010 Shiota et al. 2012
Ito et al. 2010 Ambiguity problem Ito et al. 2010 Shiota et al. 2012
Ito et al. 2010 Ambiguity problem Vertical Undetermined Horizontal 0º-40º ; 140º-180º 40º-70º ; 110º-140º 70º-110º Ito et al. 2010 Shiota et al. 2012
Ito et al. 2010 Ambiguity problem Solut. 1 Vertical Vertical Horizontal Vertical Undetermined Horizontal Ito et al. 2010 Shiota et al. 2012 Solut 2. Vertical Undetermined Undetermined Horizontal Undetermined Horizontal Final Solution Most Vertical Vertical Horizontal Undetermined Undetermined Undetermined?
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
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
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
WHERE WE ARE Adur Pastor Yabar; IAU Symposium 305; 3rd December
Where We Are 2014-04-14 Data from SST (La Palma, Spain) in 6173Å FeI Adur Pastor Yabar; IAU Symposium 305; 3rd December
South Pole Stokes I Where We Are 2014-04-14 Data From SST (La Palma, Spain) in 6173Å FeI
Stokes Q Where We Are 2014-04-14 Data From SST (La Palma, Spain) in 6173Å FeI South Pole
Stokes U Where We Are 2014-04-14 Data From SST (La Palma, Spain) in 6173Å FeI South Pole
Stokes V Where We Are 2014-04-14 Data From SST (La Palma, Spain) in 6173Å FeI South Pole
Where We Are 2014-04-14 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
Magnetic Field Intensity Where We Are 14-04-14 Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole
Magnetic Field Inclination Where We Are 14-04-14 Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole
Magnetic Field Azimuth Where We Are 14-04-14 Data from SST (La Palma, Spain) in 6173Å FeI Inversions have been done South Pole
Where We Are 14-04-14 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
Where We Are 14-04-14 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
CONCLUSION Adur Pastor Yabar; IAU Symposium 305; 3rd December
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
THANKS!