Signal processing in Python for the detection and characterization of extrasolar planets Institut d astrophysique spatial Université Paris-Sud 11 29 August 2011
1 Personal background 2 3 4 5
1 Personal background 2 3 4 5
Areas of research Science Extrasolar planets Stellar physics
Areas of research Science Extrasolar planets Stellar physics Techniques Adaptive optics Doppler spectrometry (radial velocimetry) High-precision photometry Long-baseline stellar interferometry
The choice of Python Frustrations with IDL 6.2 (2006) not (or poorly) interactive graphical windows for data inspection only low to moderate-quality graphics for publications failed to make a Fresnel-propagation library work properly costs more than a laptop
The choice of Python Frustrations with IDL 6.2 (2006) not (or poorly) interactive graphical windows for data inspection only low to moderate-quality graphics for publications failed to make a Fresnel-propagation library work properly costs more than a laptop Data-processing languages widely used for astronomy proprietay: IDL, Matlab open-source: Java, Python (promoted by the STScI), Scilab, Yorick...
1 Personal background 2 3 4 5
Transit of Mercury in front of the Sun Solar Heliospheric Observatory 7 May 2003
Transit of an exoplanet F F = ( ) 2 Rp R Jupiter 10 2 Earth 10 4
The Corot space mission Cnes mission + European partners + Brazil (165 M ) 27-cm diameter telescope, 3.5 o 2.8 o field of view 4 CCD detectors (350 1050 nm) Launched 27 Dec. 2006 for 3+3 years Polar orbit at an altitude of 900 km Science: asteroseismology + exoplanets
Corot-2 light curve 78 transits in 152 days! Alonso et al., A&A 482, L21 (2008)
Corot-2b: transit and characteristics Average transit Planet s portrait Radius = 1.429 ± 0.047 R J Mass = 3.53 ± 0.24 M J Density = 1.50 ± 0.18 Period = 1.7429964 ± 0.0000017 d Semi-major axis = 0.030 AU Host-star = G7 V
1 Personal background 2 3 4 5
Light curve prefiltering
Detection by matched-filtering
Fitting a trapezoid model
Individual transit check
Handling 10,000 light curves
1 Personal background 2 3 4 5
Corot-8b direct model
Corot-8b inverse model
1 Personal background 2 3 4 5
Recent and future work HTML output replaced by a MySQL database (done) Coding in C the cross-correlation function (future) PDF reports for every light curve using ReportLab (future)
Recent and future work HTML output replaced by a MySQL database (done) Coding in C the cross-correlation function (future) PDF reports for every light curve using ReportLab (future) Underway: implementation of a Bayesian approach with MCMC computations (PyMC?)
Recent and future work HTML output replaced by a MySQL database (done) Coding in C the cross-correlation function (future) PDF reports for every light curve using ReportLab (future) Underway: implementation of a Bayesian approach with MCMC computations (PyMC?) Notebooks in Python Have tried Sage and TeXmacs as Python interfaces to produce notebooks.
Python for teaching? For programming in L3?... C# chosen instead.
Python for teaching? For programming in L3?... C# chosen instead. For data display in L3?... Matlab chosen instead.
Python for teaching? For programming in L3?... C# chosen instead. For data display in L3?... Matlab chosen instead. For signal processing in M1?... Matlab chosen instead.
Python for teaching? For programming in L3?... C# chosen instead. For data display in L3?... Matlab chosen instead. For signal processing in M1?... Matlab chosen instead. Signal processing in M2?... Yes! using Pylab and IPython.