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 can get Radial velocity measurementsObservations of transits and eclipses Outputs: - Orbital parameters - Limits on mass Outputs: - Orbital parameters - Planetary radius - And more … A clear, direct image of a planet and its spectrum What we need Combined output: average density of a planet

Transiting planets Transit – radiation from star transmitted through the planet atmosphere – probe of planetary limb and upper atmosphere Secondary eclipse – day side of the planet, thermal radiation (at infrared) and reflected light (visible) 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 VisibleIR Probing low pressures Probing higher pressures H Lyman-  nm feature In HD b (15% absorption) Atmospheric mass loss Cometary tail of H gas Absorption of Na,K, TiO Constraints on metallicity, clouds and rainout of condensates HD 80606b (Colon et al.) Spitzer space telescope data: 3.6, 4.5 and 8  m for GJ436b Atmospheric composition from absorption of CO, CO 2, H 2 O, CH 4 Thermal properties (equilibrium?) Knutson et al.

Transit and eclipse spectrophotometry UV VisibleIR Probing reflectivity - albedo Probing temperature First detections of planetary emission by Spitzer space telescope in mid and far infrared (3.5 to 24  m) 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  m) Broad band measurements from ground based telescopes are challenging 2.1  m 4.5  m

Survey of Secondary Eclipses of Hot Jupiters with IRIS2 at Anglo Australian Telescope Broad band measurements at Ks (2.1  m) band Now extended to J (1.2  m) and H (1.6  m) Completed for 12 hot Jupiters out of sample of 30 in Ks band

How this can be achieved with IRIS2? We need 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 2.1  m

- 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 Goals of the Survey CO 2 H 2 O CO CH 4 HCN C 2 H 2 H2OH2O CH 4 /HCN CO CH 4 Wasp 19b (Zhou et al. 2014)

Addition of J (1.2  m) band measurements Some recent results

WASP 18b One of the most highly irradiated hot Jupiters, 0.94 day orbital period and 10 M Jup 3 measurements in J-band show deeper than expected and possibly variable eclipses

More data is coming… IRIS2 still rocks!