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SIAMOIS Sismomètre Interférentiel A Mesurer les Oscillations des Intérieurs Stellaires

Asteroseismology in Antarctica at Dome C  

Benoît Mosser, Michel Auvergne, Thierry Appourchaux, Annie Baglin, Caroline Barban, Claude Catala, Marc-Antoine Dupret, MarieJo Goupil, Jean-Pierre Maillard, Eric Michel, Reza

Samadi, Francois-Xavier Schmider, Frédéric Thévenin, Gérard Vauclair et al.

 Observatoire de Paris (LESIA, GEPI), IAP, IAS, UNSA/LUAN, OMP/LATT, OCA

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In 2009

has achieved a huge program

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AND THEN ?

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Scientific goals

Step 1: photometry in space

For complementary observations: photometry in space / ground based spectrometric observations• Low mass stars• Doppler information (limited granulation noise, l = 3 modes)• Long term variations• Follow up of targets revealed by COROT• Questions raised by COROT…

In the best site for long-duration continuous observations :

at Dome C in Antarctica

• Solar like oscillations• Stellar interior

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Step 2 … ground-based spectrometry

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Dome C

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Duty cycle > 90 %

during 3 months

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Properties at Dome C

• Wintering: full night = 3 months

• Duty cycle: > 90 % (Agabi, 2005)

• Much better performances compared to a network(duty cycle limited to 65%; heavy coordination)

• Conditions similar to space

Properties of Dome C are already OK for asteroseismology~ Space project

Asteroseismology at Dome C:

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Strategy for Dome C

2009/2010 Integrated project :+ small telescope+ dedicated Fourier Transform seismometer

2010+ Spectrometer + spectropolarimeter2-m class telescope

• INSU (Astronomy) / Antarctic group:- promotes observations at Dome C- has to identify small size projects to be realized as a first step

• PNPS (Stellar physics): - promotes the rapid development of a dedicated asteroseismometer to be installed at Dome C

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• Fourier Transform seismometry: the Doppler signal is deduced from a limited portion of the interferogram of the stellar visible spectrum

• FT seismometry successfully tested with the FTS at CFHT Procyon (Mosser et al. 1998, A&A 340, 457)

• Principle of an instrument dedicated to asteroseismology Photon noise limited performances:

Q = quality factor ; Ne = photoelectrons

+ low resolution dispersion (Mosser et al. 2003, PASP 115, 990)

Fourier transform seismometry

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Performances

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Photon noise limited performances SIAMOIS at Dome C, 40-cm telescope, 120 hrs, mV = 4, duty cycle = 95% ‘‘SNR’’ of circumpolar targets

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Asteroseismic targets

Observable targets with SIAMOIS and a 40-cm

telescope

• 40-cm tel : - 8 targets F, G and K, IV & V, with solar like oscillations- more than 30 red giants

- many Scuti with v sin i < 20 km/s• Program for more than 3 winterovers

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Project and instrument

• 40-cm telescope low cost, easy ‘antartization’, dedicated to the projet • Interferometer monolithic instrument

no moving part, reduced sizefiber fed

• Post-dispersion efficiency, photon noise limited performances

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Schedule

• 2004: faisability - Realisation and test of the only critical subsystem

• 2005: phase A (funded)- Design of the instrument for Antarctic- Integrated project with a small collector- Positive recommendation from the WG of PNPS (stellar physics)

• 2006: end of phase A + phase B- Design of the full instrument ; thermo-mechanical analysis- Prototype, tests….

• 2008- Transfer at Dome C

• 2009: winterover at Dome C

InterferometerJP Amans GEPI

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‘‘Big science’’  at Dome C for < 1 ME