Planet detection and characterization through high contrast imaging

Content • • • The difficulty of HCI Extrasolar planets may be detected in

Problematic Planets are faint and close …. But better for young giant planets 10

Required high contrast performances are equivalent to those required to see a moth flying

Systems with quite large mass ratio are being discovered… Fomalhaut < 3 MJ 120

First generation HCI • These discoveries were made using first generation HCI systems such

State-of-the-art HCI • Combines various techniques to provide high contrast imaging, with excellent stellar

Angular Differential Imaging • ADI exploits the fact that the field and the pupil

Spectral deconvolution • Simultaneous observation of several monochromatic images can be used to reduce

High contrast imaging pillars High-order AO: Contrast ~103 Coronagraphy: Contrast ~104 Differential imaging: Contrast

First and second generation HCI NACO SPHERE La ricerca sui pianeti extrasolari in Italia,

Second generation (XAO based) HCI Instrument Telescope Year of operation Wavelength range (µm) IFS

What is SPHERE? • SPHERE is the new high contrast imager for the VLT

First new detection with SPHERE: HR 7581 B (an M dwarf companion to a

Photometric accuracy: <0. 02 mag La ricerca sui pianeti extrasolari in Italia, Roma, 5

Spectra of HR 8799 planets (Pueyo et al. 2014) See talk by Anne-Lise Maire

Comparison between transmission and high contrast imaging spectra Transmission spectrum HD 189733 (Pont et

Astrometry of HR 8799 planets (Pueyo et al. 2014) La ricerca sui pianeti extrasolari

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Planet detection and characterization through high contrast imaging Raffaele Gratton INAF – Osservatorio Astronomico di Padova La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Content • • • The difficulty of HCI Extrasolar planets may be detected in HCI! Struggling against speckles: the principles of HCI High contrast imagers: first and second gen’s What we can do with HCI? – Detection – Characterization • Photometry • Astrometry • Spectroscopy La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Problematic Planets are faint and close …. But better for young giant planets 10 = 1 billion 6 Contrast ~10 in NIR 9 106 = 1 million Reflected light Thermal emission

Required high contrast performances are equivalent to those required to see a moth flying around a street-lamp from a satellite at 500 km height

Systems with quite large mass ratio are being discovered… Fomalhaut < 3 MJ 120 AU HR 8799 b 7 MJ 68 AU HR 8799 c 10 MJ 38 AU HR 8799 d 10 MJ 24 AU

First generation HCI • These discoveries were made using first generation HCI systems such as NACO, NIRC, or Hi-CIAO • These instruments used moderately high order AO systems (<200 actuators, sampling the pupil at ~50 cm SR(H)~0. 5) available since early 2000 s, and were not specially designed to fully exploit the potential of HCI La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

State-of-the-art HCI • Combines various techniques to provide high contrast imaging, with excellent stellar PSF suppression and stability: – a high density high frequency AO system that corrects turbulence and static optical aberrations (WFE~100 nm, SR(H)~0. 9, 5 -σ contrast at 0. 5 arcsec: ~10 -3) – coronagraphy (gain by a factor of 10) – differential imaging, in which images at different wavelengths or polarization states are observed simultaneously (further gain by a factor of 100)

Angular Differential Imaging • ADI exploits the fact that the field and the pupil rotate with respect to each other • In pupil stabilized mode, most speckles are caused by instrumental artifacts and are locked up in the pupil plane, whereas the object of interest, a companion or a disk, will rotate as the field rotates (see video_adi. avi ) • This allows distinguishing the stellar halo from the object (provided instrument is stable)

Spectral deconvolution • Simultaneous observation of several monochromatic images can be used to reduce the impact of speckles (Sparks and Ford, 2002) • For a given observation, the location of a companion around a star is constant while the location of speckles from the star increases with wavelength and their intensity decreases (see video_spectrum. avi ) • For a wide enough wavelength range this allows subtraction of the speckles. This process is known as spectral deconvolution (Thatte et al. 2007)

High contrast imaging pillars High-order AO: Contrast ~103 Coronagraphy: Contrast ~104 Differential imaging: Contrast ~106

First and second generation HCI NACO SPHERE La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Second generation (XAO based) HCI Instrument Telescope Year of operation Wavelength range (µm) IFS P 1640 Palomar 2012 1. 0 -2. 5 Yes LMIRCam LBT 2013 2. 0 -5. 0 No CLIO 2 Magellan 2013 1 -5 No GPI Gemini South 2013 1. 0 -2. 5 Yes SPHERE VLT UT 3 2014 0. 6 -2. 5 Yes Hi-CIAO upgrade Subaru 2014 Y-K Yes La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

What is SPHERE? • SPHERE is the new high contrast imager for the VLT • It just passed commissioning and is offered in P 95 • SPHERE also provides narrow-field (few arcsec), very high quality diffraction-limited imaging over the wavelength range 0. 6 -2. 5 micron • It requires a bright NGS (I<14 -16)

First new detection with SPHERE: HR 7581 B (an M dwarf companion to a K-giant)

Photometric accuracy: <0. 02 mag La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Spectra of HR 8799 planets (Pueyo et al. 2014) See talk by Anne-Lise Maire La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Comparison between transmission and high contrast imaging spectra Transmission spectrum HD 189733 (Pont et al. 2013) High contrast imaging spectrum HR 8799 c (Pueyo et al. 2014) La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014

Astrometry of HR 8799 planets (Pueyo et al. 2014) La ricerca sui pianeti extrasolari in Italia, Roma, 5 -7 novembre 2014