1Paris, May 5th 2008

Exospheric Sodium Observation of

Mercury at TNG V. Mangano ,

C. Barbieri, F. Leblanc, G. Cremonese, C. Grava

(1) INAF-Interplanetary Space Physics Institute, Roma(2) University of Padova, Astronomy Department

(3) Service d'Aéronomie du CNRS, Verrières-Le-Buisson, France(4) INAF- Astronomical Observatory of Padova

(5) CISAS- University of Padova

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TNG site and descriptionTNG site and description

The TNG (Telescopio Nazionale Galileo) is the 3.58 m Italian Alt-Az telescope located in the island of La Palma, Canaries.

It is equipped with an active optics system and its 2 Nasmyth foci host 5 instruments permanently mounted.

Among these instruments, there is SARG, an high efficiency spectrograph with an echelle grating designed for the spectral range from 370 up to 900 nm, for a resolution from R=29000 to R=164000.

Altitude 2387 m a.s.l.

Lat. 28º 45’ 28” N

Long. 17º 53’ 38” W

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Mercury Observations at TNG

2002 (August 23rd-24th) published on PSS 52 (2004) 1169-75

Barbieri C., Verani S., Cremonese G., Sprague A., Mendillo M., Cosentino R., Hunten D., First observations of the Na exosphere of Mercury with the high-resolution spectrograph of the 3.5 M Telescopio Nazionale Galileo

2003 (August 8,9 and 10th) published on ICARUS 185 (2006) 395-402

Leblanc F., Barbieri C., Cremonese G., Verani S., Cosentino R., Mendillo M., Sprague A., Hunten, D., Observation of Mercury’s exosphere: spatial distributions and variations of its Na component during August 8,9 and 10, 2003

2005 (June 29,30th, July 1th) paper in preparation (Mangano V. et al.)

2006 (June 16th to 18th) first of the IMW coordinated campaign

work still in progress

first results showed by Barbieri in Boston, 2006 Paris, May 5th 2008

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Results for the June 16, 2006 evening - 2Log10 scaleD2

For better visual clarity, I show only the D2 intensities in ADUs. Each slit is 27 arcsec long.

46,5544,48

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TNG 2005 data setJune 29th

June 30th

July 1st

During the 2005 campaign 3 nights of observation were performed (at sunset at about 19:00 UT, for 1 hour).

Main Mercury Parameters:

Angular diameter: 6.7-7.0 arcsec

Elongation: 23.9-24.7º E

Heliocentric distance: 0.42-0.43 AU

Sun-Mercury-Earth angle: 81.3-85.3 º

True Anomaly Angle 124-130 º

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Long slit (26.7” x 0.4”)

Resolution: 115000

Na filter (no order overlapping) 60 Å wide

Scan in the north-south direction: equator ± 4”

Exposure time: 120”

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SARG CCD is a mosaic of two thinned back illuminated detectors

dimensions: 2048x4096 pixels

pixel size: 13.5 µm

Phase 1: pre-analysis

D2 D1

D2

D1

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1. Correcting spectra for sky and diffuse light

2. Matching theorical dopplershifted D1 and D2 lines (red dotted line) with observed ones

Phase 2: Analysis

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3. Reproducing the Fraunhofer absorption bands throught three different profiles : a)Voigt, b) Solar spectrum, and c) straight line; comparison and extraction of the emission line

10NB: In some cases the differences are negligible, but not in other slits.

Hence, we choose the straight line profile as the best for all cases.

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4. Creation of a reflectance model of the illuminated disk by following the Hapke theory

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5. Comparison of this model with the continuum as a method to derive the calibration factor for the conversion ADU Rayleigh

6. The output provides the D2 and D1 sodium profiles along the slit

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1st night: June 29th 2005Slit

NumberObs.Time

(UT)Theoretical

PositionFinal

PositionSeeingSigma

CalibrationFactor

HYLN0045 20:20 - 2.0 + 1.3 1.7 1.92

HYLN0046 20:23 - 4.0 - 0.5 1.6 1.50

HYLN0047 20:27 - 6.0 - 2.0 1.7 2.04

2D composition /1:

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2nd night: June 30th 2005

2D composition /2:

SlitNumber

Obs.Time (UT)

Theoretical Position

Final Position

SeeingSigma

CalibrationFactor

HYNB0053 20:16 0.0 + 0.3 1.1 1.99

HYNB0054 20:19 - 2.0 - 1.4 1.1 2.75

HYNB0055 20:22 - 4.0 - 2.8 1.0 12.07

HYNB0056 20:26 - 6.0 - 4.5 1.2 35.52

HYNB0057 20:30 + 1.0 - 0.4 1.0 2.20

HYNB0058 20:33 - 1.0 + 1.5

1.2

2.12

HYNB0059 20:37 0.0 + 0.5 1.0

2.11

HYNB0060 20:40 - 3.0 - 1.5

0.9

2.62

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3rd night: July 1st 2005

2D composition /3:

SlitNumber

Obs.Time (UT)

Theoretical Position

Final Position

SeeingSigma

CalibrationFactor

HYQB0044 20:28 0.0 + 1.2 2.1 2.05

HYQB0045 20:31 - 2.0 0.0 1.8 1.70

HYQB0046 20:35 - 4.0 - 1.0 1.5 1.94

HYQB0047 20:38 - 6.0 - 3.5 1.7 2.01

HYQB0048 20:42 + 2.0 + 3.9 1.6 3.41

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Two features are clearly visible:

1. An emission peak in the southern hemisphere at mid latitude:

• Related surface feature?

• Opening of the magnetic field southern cusp?

2. A global enhancement of sodium emission during the second night (50%)

• Related solar events?

Phase 3: Interpretation

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The peak appear to be at about: 250-290º E, 10-40º S

Radar bright spots: (A. Sprague) A (15° E, 25° S), B(15° E, 55° N),C(120° E,15°N)

(J. Harmon) A (12° E, 34° S), B(17° E, 58° N),C(114° E, 11°N),

(18° E, 27° S), Bartok crater

Location of the peak

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No match with the radar bright spots.

Maybe with the faint feature associated to the Bartok crater?

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Opening of the magnetic cuspsThe mid-latitude position of the peak suggests a relation with the opening of the magnetic cusps:

IMF Bx > 0 injection in southern hemisphere

IMF Bx < 0 injection in the northern hemisphere

(-) → IMF Bx > 0

(+) → IMF Bx < 0

IMF Bx(flipped)

188 184 180 176 172time

Coronal Field

‘Wrong’ direction of the IMF Bx component!

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Solar conditions – impulsive events

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Wilcox Solar Obs. photospheric field CR#2031 SoHO/EIT (Fe XV 284 Å) image

29-June-2005 07:00 UT

Coronal HoleCoronal HoleFast StreamFast StreamActive RegionActive Region

AR0781 (CMEs)AR0781 (CMEs)20

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June 29th CME

2005 07:30 UT, v0= 350 km/s

Estimated arrival time:

• July 1st, 17:00 UT

June 28th CME

2005 20:05 UT, v0= 600/400 km/s

Estimated arrival time:

• June 30th, 03:00 UT

• June 30th, 15:00 UT

CME #2 CME #3CME #1

June 28th HALO CME

2005 16:30 UT, v0= 1750 km/s

Estimated arrival time:

• June 30th, 05:00 UT

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To summarise:

29-Jun (180) 30-Jun (181) 01-Jul (182)

20:00 UT 20:00 UT 20:00 UT

IMF Bx < 0

CME#1

CME#2

CME#3

time

is Na intensificationcorrelated to CME?

N-S asymmetry?related to IMF Bx?

Coronalhole