MERCURY ’ S EXOSPHERE OBSERVATION USING EsPadOnS/CFHT

June 2006 data review meeting, Boston, 20-21 Nov 2006

Alain Doressoundiram 1

MERCURY’S EXOSPHERE OBSERVATION USING

EsPadOnS/CFHT

Alain Doressoundiram(LESIA -Observatoire de Paris)

François Leblanc (IPSL, France)Cédric Foellmi (LAOG, Grenoble)



Observed components of Mercury's exosphere

H 3 109 ~ 23 (hot) 230 (cold)

Mariner 10

He 3 1011 ~ 6103 Mariner 10

O 3 1011 ~ 4.4 104 Mariner 10

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

Species

Subsolar column

density (cm-

2)

Near surface subsolar

density (cm-3)

Remarks

Na 0.1 - 10 1011

~ 104 From Earth

K 0.5 - 3 109

~ 102 From Earth

Ca 1.1 108 ? From Earth

KnownSpecies



ESPaDOnS is a bench-mounted high-resolution echelle spectrograph/spectropolarimeter fiber-fed from a Cassegrain module

No slit, 1.6 arcsec aperture holeSpectral range: 360 to 1050 nm at R=80,000

spectroscopy 'star only' modeLow pointing limit (8°)

CFHT, Mauna Kea, Hawaii3.58-m telescopelatitude +19° 50'longitude 155° 28'

OBSERVATIONS at CFHT/ESPaDOnS



Observational campaigns at CFHT

June 2006 runAugust 2006Apply for time in 2007



Mercury observational circumstances

Date of observations:16-17-18 June 2006

Angular size (arcsec)

Helio. distance (AU)

Geo. Distance(AU)

Illum(%)

mag

7.6 0.42 0.89 45.6 0.38

SUN

1.6" hole



UT TIMESNight 06/16/06

Object UT Start UT End Exposure Time Comments and Notes Mercury 5:18:06.232 5:19:06.273 60 R=80000 Spectroscopy

SKY 30arc S Mercury 5:24:51.507 5:25:51.548 60 R=80000 Spectroscopy Mercury 3arc N 5:28:32.666 5:29:32.707 60 R=80000 Spectroscopy Mercury 6arc N 5:31:06.763 5:32:06.804 60 R=80000 Spectroscopy Mercury 3arc S 5:34:27.060 5:35:27.101 60 R=80000 Spectroscopy Mercury 6arc S 5:39:53.582 5:40:53.623 60 R=80000 Spectroscopy

SKY 30arc S Mercury 5:43:26.691 5:44:26.731 60 R=80000 Spectroscopy Mercury 3arc Sunward

centered 5:49:58.887 5:50:27.246 28 R=80000 Spectroscopy

Night 06/17/06

Object UT Start UT End Exposure Time Comments and Notes SKY 30arc S Mercury 5:32:14.470 5:33:14.511 60 R=80000 Spectroscopy

Mercury centered 5:35:29.777 5:36:59.818 90 R=80000 Spectroscopy Mercury centered 5:38:27.393 5:39:57.434 90 R=80000 Spectroscopy Mercury centered 5:41:30.259 5:42:30.300 60 R=80000 Spectroscopy Mercury centered 5:44:05.547 5:45:05.588 60 R=80000 Spectroscopy Mercury centered 5:46:28.010 5:47:28.050 60 R=80000 Spectroscopy

SKY 30arc S Mercury 5:49:27.866 5:50:27.907 60 R=80000 Spectroscopy



UT TIMES

Night 06/18/06

Object UT Start UT End Exposure Time Comments and Notes SKY Mercury 5:17:37.072 5:18:17.110 40 R=80000 Spectroscopy

Mercury centered 5:20:43.498 5:21:23.536 40 R=80000 Spectroscopy Mercury 3arc North 3arcSunward 5:27:42.832 5:29:02.869 80 R=80000 Spectroscopy Mercury 3arc South 3arcSunward 5:32:57.368 5:34:17.404 80 R=80000 Spectroscopy

Mercury 3arc North 3arcAntiSunward 5:37:28.496 5:38:48.534 80 R=80000 Spectroscopy Mercury 3arc South 3arcAntiSunward 5:40:11.198 5:41:31.237 80 R=80000 Spectroscopy

SKY Mercury 5:44:01.725 5:44:41.765 40 R=80000 Spectroscopy Mercury centered 40 R=80000 Spectroscopy Mercury centered 5:48:24.93 5:50:07.01 60 R=80000 Spectroscopy Mercury centered 5:50:52.13 5:51:43.46 ? R=80000 Spectroscopy

Raw data and extraction (Na line)

Raw 2D echelle spectrumwhere 40 spectral orders are seen

Order containing the Na D2 and D1 line (589.2 and 589.8 nm)

Na emission line

Extracted 1D spectrum589.2 nm 589.8 nm



Main Objectives

Detect simultaneous Na, K and Ca emission lines

Detect new lines in the spectral range of Espadons

Variability over 3 nights period



Observations



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

Night 16 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







Night 17 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







Night 18 June 2006



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)



Other telescopes usedfor our program



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

NTT, La Silla, Chile3.58-m telescopelatitude -29º 15’longitude 70º 44'

3 nights october 20053 nights october 2006

MERCURY ’ S EXOSPHERE OBSERVATION USING EsPadOnS/CFHT

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