Survey
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Characterisation of hot Jupiters by secondary transits observed with IRIS2 Lucyna Kedziora-Chudczer (UNSW) George Zhou (Harvard-Smithsonian CfA) Jeremy Bailey (UNSW) Daniel Bayliss (University of Geneva) Chris Tinney (UNSW) Legacy of Kepler Mission What we need A clear, direct image of a planet and its spectrum What we can get Radial velocity measurements Outputs: - Orbital parameters - Limits on mass Observations of transits and eclipses Outputs: - Orbital parameters - Planetary radius - And more … Combined output: average density of a planet Transiting planets Secondary eclipse – day side of the planet, thermal radiation (at infrared) and reflected light (visible) Transit – radiation from star transmitted through the planet atmosphere – probe of planetary limb and upper atmosphere Orbital phase variations – measure of temperature gradient between day and night side of the planet (not only for transiting planets) Transit and eclipse spectrophotometry UV Probing low pressures H Lyman-a 121.6 nm feature In HD 209458b (15% absorption) Visible Probing higher pressures Absorption of Na,K, TiO IR Spitzer space telescope data: 3.6, 4.5 and 8mm for GJ436b Knutson et al. Atmospheric mass loss Cometary tail of H gas HD 80606b (Colon et al.) Constraints on metallicity, clouds and rainout of condensates • Atmospheric composition from absorption of CO, CO2, H2O, CH4 • Thermal properties (equilibrium?) Transit and eclipse spectrophotometry UV • Probing reflectivity - albedo Visible Probing temperature IR First detections of planetary emission by Spitzer space telescope in mid and far infrared (3.5 to 24 mm) • Spitzer measurements exist for ~50 planets Spitzer observations of HD189733b Charbonneau et al. The best sampled spectrum of the exoplanet VSTAR model Eclipses in near infrared • From Hubble Space Telescope Wide Field Camera 3 (0.8 – 1.7 mm) • Broad band measurements from ground based telescopes are challenging 4.5 mm 2.1 mm Survey of Secondary Eclipses of Hot Jupiters with IRIS2 at Anglo Australian Telescope • Broad band measurements at Ks (2.1mm) band • Now extended to J (1.2mm) and H (1.6mm) • Completed for 12 hot Jupiters out of sample of 30 in Ks band How this can be achieved with IRIS2? We need 10-3 magnitude precision infrared photometry over typically 5 hours • IRIS2 is a stable instrument with field of view sufficient for many reference stars • Telescope’s precise tracking allows measurements on the same pixel of the detector • Low altitude of AAT means that water vapour is always saturated above the telescope Wasp 19b at 2.1mm Goals of the Survey - 30 hot Jupiters sample will double the number of planets with measured temperature Probing atmospheres of individual sources - done best in cases where there is good spectral coverage in other bands Exploring the population of hot Jupiters with colour-magnitude and colour-colour diagrams as is done for brown dwarfs Wasp 19b (Zhou et al. 2014) CO2 H2O CO CH4 HCN C2H2 CH4/HCN CO H2O CH4 Some recent results Addition of J (1.2mm) band measurements WASP 18b One of the most highly irradiated hot Jupiters, 0.94 day orbital period and 10 MJup 3 measurements in J-band show deeper than expected and possibly variable eclipses More data is coming… IRIS2 still rocks!
