MERCURY ’ S EXOSPHERE OBSERVATION USING EsPadOnS/CFHT

1. MERCURY’S EXOSPHERE OBSERVATION USING EsPadOnS/CFHT Alain Doressoundiram(LESIA -Observatoire de Paris) François Leblanc (IPSL, France) Cédric Foellmi (LAOG, Grenoble) Alain Doressoundiram

2. Observed components of Mercury's exosphere Known Species Mariner 10 Solar Occultation (Broadfoot et al. 1976) At terminator: neutral density < 107 cm-3 Mariner 10 Radio Occultation (Fjelbo et al. 1976) Electronic density around Mercury < 103 cm-3 Alain Doressoundiram

3. OBSERVATIONS at CFHT/ESPaDOnS • ESPaDOnS is a bench-mounted high-resolution echelle spectrograph/spectropolarimeter fiber-fed from a Cassegrain module • No slit, 1.6 arcsec aperture hole • Spectral range: 360 to 1050 nm at R=80,000 • spectroscopy 'star only' mode • Low pointing limit (8°) CFHT, Mauna Kea, Hawaii 3.58-m telescope latitude +19° 50' longitude 155° 28' Alain Doressoundiram

4. Observational campaigns at CFHT • June 2006 run • August 2006 • Apply for time in 2007 Alain Doressoundiram

5. Mercury observational circumstances Date of observations: 16-17-18 June 2006 1.6" hole SUN Alain Doressoundiram

6. UT TIMES Alain Doressoundiram

7. UT TIMES Alain Doressoundiram

8. Raw data and extraction (Na line) Order containing the Na D2 and D1 line (589.2 and 589.8 nm) Na emission line Raw 2D echelle spectrum where 40 spectral orders are seen Extracted 1D spectrum 589.2 nm 589.8 nm

9. Main Objectives • Detect simultaneous Na, K and Ca emission lines • Detect new lines in the spectral range of Espadons • Variability over 3 nights period Alain Doressoundiram

10. Observations Alain Doressoundiram

11. Night 16 June 2006 • Spectrum of the top: • Sum of 5 individual exposure with a total time of 300 s of observation of Mercury , Sky has been subtracted  Black solid line • Asteroid: one single exposure of 600 s of Pallas, Sky has been subtracted • Blue solid line • Solar spectrum from atlas  Orange solid line • Spectrum at the bottom: Ratio of the spectrum of Mercury and of the spectrum of the Asteroid • Doppler has been evaluated by using the sodium line during the third night (06/18/2006) therefore not very precisely estimated for this night •  Orange vertical line: position of the solar line as seen on Earth •  Green vertical line: position of the solar line corrected for the doppler of Mercury/Sun and Mercury/The Earth •  Blue vertical line: position of the exospheric emission corrected for the doppler of Mercury/The Earth Alain Doressoundiram

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15. Night 17 June 2006 • Spectrum of the top: • Sum of 5 individual exposure with a total time of 360 s of observation of Mercury (for this night the spectra were saturated in the red, therefore available data are up to 5270 A), Sky has been subtracted  Black solid line • Asteroid: one single exposure of 720 s of Vesta, Sky has been subtracted • Blue solid line • Solar spectrum from atlas  Orange solid line • Spectrum at the bottom: Ratio of the spectrum of Mercury and of the spectrum of the Asteroid • Doppler has been evaluated by using the sodium line during the third night (06/18/2006) therefore not very precisely estimated for this night •  Orange vertical line: position of the solar line as seen on Earth •  Green vertical line: position of the solar line corrected for the doppler of Mercury/Sun and Mercury/The Earth •  Blue vertical line: position of the exospheric emission corrected for the doppler of Mercury/The Earth Alain Doressoundiram

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19. Night 18 June 2006 • Spectrum of the top: • Sum of 7 individual exposure with a total time of 460 s of observation of Mercury (for this night the spectra were not saturated), Sky has been subtracted •  Black solid line • Asteroid: one single exposure of 1200 s of Vesta, Sky has been subtracted • Blue solid line • Solar spectrum from atlas  Orange solid line • Spectrum at the bottom: Ratio of the spectrum of Mercury and of the spectrum of the Asteroid • Doppler has been evaluated by using the sodium line during the third night (06/18/2006) therefore not very precisely estimated for this night •  Orange vertical line: position of the solar line as seen on Earth •  Green vertical line: position of the solar line corrected for the doppler of Mercury/Sun and Mercury/The Earth •  Blue vertical line: position of the exospheric emission corrected for the doppler of Mercury/The Earth Alain Doressoundiram

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24. Conclusions • CFHT/ESPADON: good plateform (efficiency, low limit) but…no slit (pb of diff refraction) • Detection of Na and K. This is the second time that a simultaneous obs. of Na and K is done • Possible simultaneous detection of Ca • Upper limits for other species (Mg, Al) • Identification of new species • May be but some works to be done to increase Signal/Noise (better normalization...) • Need of a better surface analog (a star analog of the Sun) • Need of longer time of exposure along parallactic axis (to get best S/N) Alain Doressoundiram

25. Other telescopes usedfor our program Alain Doressoundiram

26. NTT/EMMI • EMMI is a multi-purpose instrument used in echelle spectroscopy mode • Whole 385 to 855nm at R=75000, ~0.025 A/pix • Slit: 0,8" width 10" long 3 nights october 2005 3 nights october 2006 NTT, La Silla, Chile 3.58-m telescope latitude -29º 15’ longitude 70º 44' Alain Doressoundiram