POLARIMETRY OF THE SMALL BODIES OF THE SOLAR SYSTEM Stefano Bagnulo Armagh Observatory Alberto...
-
Upload
everett-morgan -
Category
Documents
-
view
216 -
download
3
Transcript of POLARIMETRY OF THE SMALL BODIES OF THE SOLAR SYSTEM Stefano Bagnulo Armagh Observatory Alberto...
POLARIMETRY OF THE SMALL BODIES OF THE SOLAR SYSTEM
Stefano BagnuloArmagh Observatory
Alberto CellinoINAF Torino
3rd SOLARNET WORKSHOP Granada, 27 May 2015
Ludmilla KolokolovaUniversity of Maryland
Irina BelskayaKharkiv National University
Gian Paolo TozziINAF Arcetri
POLARIZATION BY REFLECTION
- > 0
http://background.uchicago.edu/~whu/intermediate/polarization/polar1.html
THE ALBEDO-POLARIZATION
RELATIONSHIP
Log(pv) = C1 Log(h) + C2
Log(pv) = C3 Log(Pmin) + C4
C1 ≈ C2 ≈ C3 ≈ C4 ≈ -1
THE ALBEDO-POLARIZATION
RELATIONSHIP
Cellino et al. (2015), MNRAS (in press)
Polarimetric slope (%/DEG)Pmin (%)
1
0.1
1
asteroids Trojans
Alb
ed
o
|Pmin
|, %
20.5
0.2
0.5
0.05
0.2
THE ALBEDO-POLARIZATION
RELATIONSHIP
WHAT ELSE POLARIMETRIC CURVES TELL
US?
EMPIRICAL FIT TO THE POLARIZATION
CURVES TAXONOMY (PENTTILA ET AL
2005)
AGGREGATES
• Radius of the monomers ~ 0.1 µm• Number of monomers > 256• Refractive index (based on in-situ data for
comet Halley): 1.88-i0.47 at l=0.45 µm and
1.98-i0.48 at l=0.60 µm• Composition: silicate 31.76%, iron 2.56%,
carbonaceous materials 65.68% (1/3 organic
refractory, 2/3 amorphous carbon)
0.01
0.1
1
10
100
Ap
180120600
(deg)
1.0
0.8
0.6
0.4
0.2
0.0
P
10-14
10-13
10-12
10-11
10-10
S1
1 /k2 (m
2)
0.01
0.00
P
100
BCCAN=256
CIRCULAR POLARIMETRY
Violation of the mirror symmetry in the medium
• Asymmetry of the medium where light experience multiple scattering
• Asymmetry of the optical properties of the material (e.g., asymmetry in crystal structure of the material, or in the structure of the molecules)
THE BUILDING BLOCKS OF LIFE (AS WE
KNOW) ARE CHIRAL
All amino acids of biological origin are left-handed
CIRCULAR POLARIMETRY
Violation of the mirror symmetry in the medium
• Asymmetry of the medium where light experience multiple scattering
• Asymmetry of the optical properties of the material (e.g., asymmetry in crystal structure of the material, or in the structure of the molecules)
• Asymmetry of the scatterers themselves (alignment of particles due to some mechanism)
PRELIMINARY QUESTION
How polarization spectra depend on phase-angle?
DOES THEIR SHAPE CHANGE WITH PHASE-ANGLE?
Results fully consistent with the analysis carried out by Lupisko & Kiselev (1995) and by Belskaya et al. (2009) based on multi-colour broadband polarimetry