Influence of exozodiacal dust clouds in mid-IR Earth-like planet detection

1. Influence of exozodiacal dust clouds in mid-IR Earth-like planet detection Denis Defrère University of Liège and Olivier Absil1, Roland den Hartog2, Charles Hanot1 and Chris Stark3 • University of Liège (Belgium) • (2) Netherlands Space Research Institute (SRON, The Netherlands) • (3) University of Maryland (USA) Barcelona, 2009

2. Darwin/TPF project • Mid-IR space-based nulling interferometer (6 to 20 µm) • 2-year detection • Required SNR = 5 (broad band) • 10% F stars, 50 % G stars, 30% K stars and 10% F stars • 3-year spectroscopy • R=20 from 6 to 20 µm • SNR=10 for λ > 7.2 µm Detection of about 200 Earth-like planets with possible follow-up H20 spectroscopy for about 20

3. Darwin/TPF project • Mid-IR space-based nulling interferometer (6 to 20 µm) • 2-year detection • Required SNR = 5 (broad band) • 10% F stars, 50 % G stars, 30% K stars and 10% F stars • 3-year spectroscopy • R=20 from 6 to 20 µm • SNR=10 for λ > 7.2 µm Detection of about 200 Earth-like planets with possible follow-up H20 spectroscopy for about 20

4. Influence of exozodiacal disks in mid-IR Earth-like planet detection • Exozodi flux ~ 300× Earth flux at 10 µm • Photon noise  ~100 zodi tolerable Defrère et al. 2009 (submitted)

5. Influence of exozodiacal disks in mid-IR Earth-like planet detection • Exozodi flux ~ 300× Earth flux at 10 µm • Photon noise  ~100 zodi tolerable

6. Influence of exozodi asymmetries Stark & Kuchner 2008 • Symmetric parts removed (chopping) • Asymmetries seen in chopped response • 5 to 15 zodi tolerable depending on system inclination Planet

7. Influence of exozodi asymmetries • Offset => asymmetric brightness • Less problematic than clumps for “reasonable” offsets

8. Summary • Asymmetric structure brightness rather than shot noise drives the SNR • Relevance of long imaging baseline • 15 zodi tolerable for 5-s detection • with disc inclination • Relevance of precursor missions!