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Primera parte. Astronomical Polarimetry Optical and NIR applications Antonio Pereyra Observatório Nacional (ON) Rio de Janeiro - Brazil.

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Presentation on theme: "Primera parte. Astronomical Polarimetry Optical and NIR applications Antonio Pereyra Observatório Nacional (ON) Rio de Janeiro - Brazil."— Presentation transcript:

1 Primera parte

2 Astronomical Polarimetry Optical and NIR applications Antonio Pereyra Observatório Nacional (ON) Rio de Janeiro - Brazil

3 LNA site

4

5

6 Polarimetry at LNA Instrument: IAGPOL –Polarimetric module –Operations modes: Imaging: –Point sources –Extended sources –Optical (w/ CCDs) –NIR (w/ CamIV) Spectropolarimetry –w/ EIFU (Integral Field Unit)

7 Retarder (λ/2 or λ/4) Analyser (Savart / Polaroid) Filters (Clear, U,B,V,R,I) Optical axis Wheel axis Detector (CCD, NIR – J,H,K) IAGPOL - Optical System

8 Measuring the Polarization Stokes parameters:

9 Measuring the Polarization Linear polarization: U’ (x100) P 2θ2θ Q’ (x100)

10 Transmitted intensity through waveplate /2 + Savart: Ni +Ni + Ni –Ni – I’(  i ) = ½ [I ± Q cos 4  i ± U sin 4  i ] I I’ Measuring the Polarization

11 Example: Crowded field

12 Modulation (waveplate+Savart)

13 HD (optical polarized standard) Z  P R =(5.67  3° (Tapia 88’) P = (Q’ 2 + U’ 2 ) ½  100 θ = ½ tan -1 (U’/Q’)

14

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16 Applications

17 Interstellar Medium Unpolarized light from background star Aligned grain w/ angular momentum // B B Linear polarized light

18 Musca Dark Cloud Feitzinger & Stüve 84

19 MDC 2.5°x2.5 ° DSS

20 Pereyra & Magalhães 00 B ~ perpendicular to the longest axis of MDC Results support models of collapse along B

21 Pereyra & Magalhães 00 B ~ perpendicular to the longest axis of MDC Results support models of collapse along B

22 Pereyra & Magalhães 00 B ~ perpendicular to the longest axis of MDC Results support models of collapse along B

23

24 2%2% 2MASS (H) DDS (optical) IRAS ’x9’ Pereyra & Magalhães 05 Optical vs NIR

25 Sigue segunda parte


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