a step

A STEPA STEP

Antarctica Search for Transiting Extrasolar Antarctica Search for Transiting Extrasolar

PlanetsPlanets

Kick-off meetingKick-off meetingNice, September 5-6, 2006Nice, September 5-6, 2006

ProgrammeProgramme

ParticipantsParticipants

20 17

Tonight, Tonight, 20h20h

ProgrammeProgramme

The future of transit searchesThe future of transit searches

Combined to radial-velocimetry, it is the only way to determine the density, hence the global composition of a planet

Transit spectroscopy offers additional possibilities not accessible for “normal” planets

examples:A correlation between the metallicity of stars and planets (Guillot et al. A&A 2006)

Stellar formation model constraints (Sato et al 2005)

We foresee that exoplanetology will have as its core the study of transiting exoplanets

Exoplanets: present lessonsExoplanets: present lessons

• Exoplanets are relatively frequent:– About 10% of solar-

type stars possess planetary companions detectable by radial velocimetry

• That represent numerous targets: at least 100000 planets companions to stars with magnitude mv<=12.5.

The number of transiting giant planets in the sky can be estimated from radial velocity measurements.

• Number of transiting giant planets in the sky: about 200 around stars with magnitudes < 10.5

• Strong interest in detecting transits– of small planets– of a very large number of planets– around bright stars

• Limitations of transit surveys are still not well understood (red noise).

Exoplanets: present lessonsExoplanets: present lessons

The future of transit searchesThe future of transit searches2 future milestones:•COROT: 60 000 stars (nominal mission), mv=11 to 16, for 150 days, launch oct. 2006•KEPLER: 100 000 stars, mv=11 to 14 for 4 years, + 70 000 for 1 year, launch end 2008

Limited by data transmission to EarthA problem for the detection of small planets: background eclipsing binaries

Future missions should:•Detect more planets•Diversify the targets•Detect smaller planets

from SPACE•Natural but costly•Limited in telescope size, number of instruments...

from DOME C•Promising but uncertain•Requires precursor mission(s)

Why transit searches at Dome C?Why transit searches at Dome C?

•Continuous night for 3 months•Excellent weather

Questions:We don’t know how the following factors will affect transit surveys:

•Sky brightness & fluctuations•Presence of the moon•Generally, systematics effects due to the combination of astrophysical, atmospheric and instrumental noises

Technical problems•Autonomous operations in cold (-50°C to -80°C) conditions•Temperature fluctuations•Icing•Electrical discharges

A STEP: the philosophy behindA STEP: the philosophy behind

•Prepare future photometric projects for planetary transit detection at Dome C

•Use available equipment, minimize development work for a fast implementation of the project

•Directly compare survey efficiency at Dome C with other surveys (e.g. BEST 2 in Chile for the same target field)

A STEP Objectives A STEP Objectives

1. Determine the limits of Dome C for precise wide field photometry (Scintillation and photon noise … or other noise sources ?)

2. If the site is competitive with space and transit search limits are well understood, establish the bases of a mid-term massive detection project (large Schmidt telescope or network of small ones)

3. Search for transiting exo-planets and characterization of these planets – Detection of bright stars oscillations.

A good phase coverage is determinant to detect the large majority of transits from ground

OGLE: transits discovered•really short periods P ~ 1 day (rare !)•stroboscopic periods

Hot Jupiters: periods around 3 days, depth ~1%

Probability of detection of a transit for a survey of 60 days

With OGLE

For the same telescope with a permanent phase coverage

Continuous observationsWith a “classical” survey, only the “stroboscopic” planets are detectable !

Observing at dome C – Lessons from the Observing at dome C – Lessons from the first two winter campaigns (1)first two winter campaigns (1)

Confirmation by the first winter campaign of the exceptional phase coverage (cloud coverage, austral auroras)

Environmental systematic effects considerably reduced:• air mass• timescale of environmental parameters evolution

Expectations for future transits search programs• low scintillation

« First Whole atmosphere night seeing measurements at Dome C, Antarctica » Agabi, Aristidi, Azouit, Fossat, Martin, Sadibekova, Vernin, Ziad

An exceptional phase coverage …

Observing at dome C – Lessons from the Observing at dome C – Lessons from the first two winter campaigns (2)first two winter campaigns (2)

… But a lot of technical difficulties to take into account

Frost – different Behaviour for different telescopes

Telescope mounts misfunctioning at really low temperature

Differential dilatationsinside the telescope

Observatoire de la Côte d'Azur (Laboratoires Cassiopée et Gemini):

Tristan Guillot (PI)

Scientific preparation, operation supervision, preparation of modelling tools, analysis of the results and scientific interpretation

Francois Fressin (IS)Scientific and technical preparation, modelling tools, analysis of the results and scientific interpretation

Alain BlazitResponsible of the camera team; Developpement of test and acquisition tools.

Jean GayFollow-up of the telescope conception; Technical preparation, optical properties modelling

Yves Rabbia Telescope environment, follow-up of the telescope conception

Jean-Pierre Rivet Telescope environment, flat fielding system

Dominique Albanese Camera control softwares & camera testing expertise

Laboratoire Universitaire d'Astrophysique de Nice:

François-Xavier SchmiderScientific and technical preparation (telescope), Dome C logistics, analysis of the results and scientific interpretation

Karim Agabi (PM)Technical preparation, Dome C logistics, telescope design and telescope control systems

Jean-Batiste DabanTechnical preparation, Dome C logistics, telescope design and telescope control systems

Eric FossatDome C logistics, analysis of the results and scientific interpretation

Lyu Abe Quality control, tests and installation

Cécile Combier Telescope and camera control softwares

François Jeanneaux Mechanical study of the camera environment

Yan Fantei Temperature regulation system, camera control system

Observatoire Astrophysique de Marseille Provence (LAM & OHP):

Claire MoutouScientific preparation, follow-up of transit candidates, photometric reduction

Magali Deleuil Scientific preparation, follow-up of transit candidates

Marc FerrariConsulting on optical properties of the telescopes, tests and optical simulations

François Bouchy Scientific preparation, follow-up of transit candidates

Antoine Llebaria Image processing, stellar photometry

Michel BoerResponsible for providing a telescope control system based on TAROT, scientific interpretation

Hervé Le Corroler Scientific interpretation

Alain Klotz Telescope and camera control software, scientific interpretation

Auguste Le van Suu Computer interfaces, telescope control system

Jérome Eysseric System engineer

Claudine Carol Computer engineer

Observatoire de Genève:

Frédéric PontScientific preparation, specifications, analysis of the results, follow-up of transit candidates, scientific interpretation

Deutsches zentrum für Luft und Raumfart:

Anders EriksonAdaptation of the data reduction pipeline; Experience with running the transit surveys BEST (OHP) and BEST II (La Silla)

Heike RauerScientific preparation, specifications, analysis of the results, comparison of BEST II / A STEP data

THEA STEP TEAM



































THEA STEP TEAM


















Yan Fantei

















THEA STEP TEAM




































THEA STEP TEAM

A STEP Telescope

CCD DW 436 (Andor)Size 2048 x 2048Pixel size 13.5 m1.74 arcsec on sky

A STEP Characteristics:

Camera use:Defocused PSFPSF sampling: FWHM covering ~4 pixelTime exposure: 10sReadout time: 10s

Telescope mount:German Equatorial Astrophysics 1200With controlled heatingPointing precision tolerated ~.5”

Data storage: ~500 GB /campaignData retrieval at the beginning of Antarctic Summer for first campaigns

A STEP Camera : Andor DW436

-2048x2048 pixel-Backwards illuminated CCD-Limited intra-pixel fluctuations (Karoff 2001)-Excellent quantum efficiency in red-USB2 with antarctisable connection-Performances guaranted by constructor

A precise photometric telescope at Dome C

Specific devices under study :•External screen for flatfields•Temperature stabilization•Controlled heating for mobile parts•Antarctized connections•Redundant data storage facility•Semi-automatical

Telescope tube:INVAR structure With Carbon fiber coverage

Thermal enclosure for focal instrumentation

Wynne Corrector4Mpixel DW436 CCD

StatusStatus

• Fully funded (OCA/LUAN/OAMP):– Agence Nationale de la Recherche (yet to come)

• 2006-2009 (3 years)

– Commission Specialisée Astronomie (INSU)• Camera (2006)

– Programme National de Planétologie• Phase 0 (travel)

Schedule of A STEP

Goals of this meetingGoals of this meeting

• Learn from other experiences• Converge on scientific specifications• Define instrumental specifications• Choose telescope, mount & camera• Define working packages

a step

Documents

detection of small planets

planets companions

metallicity of stars

planetary transit detection

transiting exoplanets

limits of dome c

planets guillot

transit search limits