SIAMOIS Sismomètre Interférentiel A Mesurer les Oscillations des Intérieurs Stellaires

1. SIAMOIS Sismomètre Interférentiel A Mesurer les Oscillations des Intérieurs Stellaires Seismic Interferometer to Measure Oscillations in the Interior of Stars Tristan Buey, Benoît Mosser, Claude Catala, Pernelle Bernardi, Jean-Christophe Leclech, Alain Piacentino, Thierry Appourchaux, Jean-Pierre Maillard, François-Xavier Schmider, Jean-Baptiste Daban, François Fressin, Frédéric Thévenin, Stéphane Charpinet, Michel Dupieux, Denis Fappani, Philippe Mathias et al. Observatoire de Paris/LESIA, IAS, UNSA/LUAN, OMP/LATT, IAP, OCA Arena Workshop, Tenerife

2. Asteroseismology Two methods: photometry = space-based observations spectrometry = ground-based observations • Advantages of Doppler measurements:- complementary observations • Bright stars • Low mass stars • reduced granulation noise, modes l=3 Scientific requirements: continuous observations & longduration Arena Workshop, Tenerife

3. SIAMOIS at Dome C Project ~ spatial organization Quasi-automatic, simple setup Reduced mass, power, telemetry Demanding site Arena Workshop, Tenerife

4. Instrument Instrument Dedicated Telescope Bonnette Vacuum pump Thermo-mechanical structure. Optical bench. Optical fibers : signal and calibration Interferometer Camera Calibration Command/control system: Acquisition,image processing … Arena Workshop, Tenerife

5. Overall description • Divided in four sub-systems : • a dedicated Telescope with its Bonnette (telescope guiding and fiber coupling). • an Interferometer and a CCD Camera. • a structure for thermal and mechanical control. • a command/control software system (CCS). • Divided among five laboratories : • GIGT / OMP (Observatoire Midi-Pyrénées): Bonnette • LUAN / OCA (Observatoire Côte d’Azur): Telescope • IAS (Institut d’Astrophysique Spatiale): Thermal structure • LESIA / OPM (Observatoire Paris-Meudon): Interferometer • CSIC from Institutode Astrofisica de Andalusia (in discussion). CCS • One associated private contractor : • SESO (Société Européenne de Systèmes Optiques). Optics Arena Workshop, Tenerife

6. Instrument Optical Fiber • 40-cm telescope low cost, dedicated to the project • Interferometer monolithic instrument • no moving parts, reduced size • fiber fed • Post-dispersion efficiency, photon noise limited performances, wide spectral range from 400 to 560nm. For more technical details have a look at the poster. Arena Workshop, Tenerife

7. Planning Planning • 2006 • design • Achievement of the feasibility phase. • 2007 • thermo-mechanical analysis • Qualification tests. • 2008 • PDR • FDR • 2009 • integration • 2010 • tests • summer campaign: Dome C • 2011 • - first winter at Dome C Cost : 860 k€ Including ANR : 460 k€ For phase A in 2006 (ACI + CSA + PNPS) : 116 k€ Arena Workshop, Tenerife

8. The constraints • Of the site: • Very difficult to fix anything at Dome C • Wintering assumes a minimum maintenance. • Rather hard environmental conditions; large temperature range, • long travel to the site; shocks and vibrations. • Of development: • Small budget and short planning… • Observation requirements : 90% of duty cycle. • Design: • Highly reliable instrument with easy set up and maintenance. • Qualification like a space instrument for the critical components • Commercial approach for the delivery • Minimal customization and technological developments. • Fully automated instrument for the main (and very simple) mode of observation. • Spares to replace the malfunctioning elements. Arena Workshop, Tenerife

9. Response to the Dome-C constraints • Qualification : • Telescope and bonnette outside --> Fully qualified (-100°C/+25°C). • Mechanical bench, thermal control --> No need to be qualified. • Optical components --> Light qualification(-30°C/+25°C), care during transportation, inside a heated shelter. Specific optical fiber connector to be qualified (soon) at -100°C. • Simplification : • The instrument is completely tested and set up before arriving in Dome-C. Only standard mechanical integration and simple good health tests are needed. • Apart from calibration modes at the beginning of the observation, only one observation mode, requiring no human intervention (or by remote control). • Apart from the active tracking control loop, no complex control inside the instrument, no critical moving parts (simple shutter). Arena Workshop, Tenerife

10. Response to the Dome-C constraints • Automation: • Pointing and tracking star: Telescope may point a region of the sky, the bonnette uses a guiding CCD to track the target (control loop). • The telescope makes a U-turn every 24 hours to follow the movement of the Earth (specific mechanism allows the rolling-up of the cables). • Frame Acquisition: the spectra are automatically acquired by the control/command system with all the house-keeping of the instrument. • The thermal control is based on a simple heating system and passive filtering and is naturally automatic. • The mechanical control is based on active autonomous suspension. • The data during the main observation mode are processed via a constant pipeline for: visualization (remote control), data sending to Europe, storage. Arena Workshop, Tenerife

11. The Command/Control System First estimation around 200ko/day Arena Workshop, Tenerife

12. Dome C: a unique site for Asteroseismology 3-month of continuous observation with duty cycle ~ 90% A specific scientific program after High performances possible with a 40-cm collector Pioneering project at Dome C FT seismometer: suitable concept for installation and setup at Dome C Multiplex advantage of FT spectrometry Small instrument : < 300kg, < 2m3, < 1kW, … Fairly fast development with a demonstrated feasibility. Fully automated for the main observational mode. Conclusion ‘‘Big science’’  at Dome C with a budget < 1 M€, with little maintenance and limited human intervention. Arena Workshop, Tenerife