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Preliminary Design of the Spectropolarimeter for Arago Martin Pertenaïs 1,2 Coralie Neiner 1 (PI), Laurent Parès 2, Jean-Michel Reess 1, Pernelle Bernardi.

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Presentation on theme: "Preliminary Design of the Spectropolarimeter for Arago Martin Pertenaïs 1,2 Coralie Neiner 1 (PI), Laurent Parès 2, Jean-Michel Reess 1, Pernelle Bernardi."— Presentation transcript:

1 Preliminary Design of the Spectropolarimeter for Arago Martin Pertenaïs 1,2 Coralie Neiner 1 (PI), Laurent Parès 2, Jean-Michel Reess 1, Pernelle Bernardi 1, Frans Snik 3, Gerard van Harten 3 1 Paris Observatory (FR) 2 IRAP-CNRS, University of Toulouse (FR) 3 Leiden Observatory, Leiden Univsersity (NL) 1 Punta Leona 2 nd December 2014

2 François Arago : Arago discovered rotary polarization experimentally (Quartz) Polarimetry was born !!

3 Scientific goals 3 What is the life cycle of matter ? (star formation, evolution and death ) ISM Characterization Young (PMS) stars in accretion All kinds of stars (Massive stars, Solar-like stars…) Late stages of evolution (Supergiants, supernovae,…) How do stars impact the formation of planets and the emergence of life? Star-Planet interactions (stellar wind, magnetic interaction,…) Space weather (irradiation of the planet by the star,…)

4 Specifications SpecificationRequirement Spectral range[119 nm ; 888 nm] UV Resolution Visible Resolution S/N100 Typical exp. time30 min (OBA stars, V=7) 1h (FGK stars, V=7) Target MagnitudeV=3-10 V rad accuracy1 km.s -1 (in absolute) 0.1 km.s -1 (for magnetic fields measurement) Polarization accuracy

5 Instrument Scheme 5

6 Telescope 6 Spec. : - SNR V=7 Star - 30 min exposure time  1.3m diameter Cassegrain telescope F/13

7 Instrument Scheme 7

8 Polarimeter 8 Aim : create a polychromatic polarimetric modulator 4 MgF 2 stacked wave plates with fast-axis angle and thicknesses: (  1,d 1 ), (  2,d 2 ),(  3,d 3 ),(  4,d 4 ) Optimization on these 8 variables The stack of the 4 plates takes 6 different angular positions (0°,30°,60°,90°,120° et 150°) d1d1 d2d2 d3d3 d4d4 11 33 22 44

9 Polarimeter 9 Aim : create a polychromatic polarimetric modulator * Optimum modulation and demodulation matrices for solar polarimetry, JC del Toro Inista and Collados (2000)

10 Polarimeter 10

11 Instrument Scheme 11

12 Spectrograph 12

13 Instrument Scheme 13 Classical CCD detector (13µm pixel pitch) MCP Detectors (20µm pixel pitch)

14 To take home 14 High-resolution spectropolarimetry Precise Full Stokes (IQUV) measurement From FUV (119 nm) to NIR (888 nm) Exciting science ! Thank you for your attention ! Contacts :

15 15

16 16 Thank you for your attention !

17 SNR figures 17 SNR Wavelength (nm) SNR Wavelength (nm) T=9790 K Mag = 10 Exposure Time = 30min T=16000 K Mag = 7 Exposure Time = 30min Considering an optical transmission in the UV of 3% and 10% in the VIS, and a quantum efficiency in the UV of 35% and 70% in the visible

18 Spectral band Minimum SNR Magnitude VSpectral typeMaximum exposure time [min] Visible [ ] nm 1007all30 UV [ ] nm 1007OBA30 UV [ ] nm 1007FGK60 UV [ ] nm Chromospheric emission lines of M dwarfs 60 18

19 Birefringence MgF2 19

20 Focal planes 20 VISIBLE Frame size 30 x 30 mm UV Frame size 120 x 14 mm 100 mm Visible :

21 Back-up polarimeter 21 x 


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