1. Reflected Light From Extra Solar Planets Modeling light curves of planets with highly elliptical orbits Daniel Bayliss, Summer Student, RSAA, ANU Ulyana Dyudina, RSAA, ANU Penny Sackett, RSAA, ANU

2. Introduction 119 extra solar planets detected. – 118 found by precise radial velocity measurements. – 1 by found by transit photometry. No reflected light from extra solar planets detected to date, however the albedo of τ Boo constrained by lack of signal (Charbonneau et al.,1999, ApJ, 522, L145).

3. Reflected light Amount of reflected light given by: p=albedod=planet-star separation  =phase function R p =planet radius

4. Space Photometry Current photometric precision limited by atmosphere to around L P /L * ~50 x 10 -6. Canadian micro satellite MOST target list includes 3 stars with planets (close-in, circular). NASA’s Kepler satellite (2007) with 100,000+ target stars. Predicted to achieve precision of L P /L * < 10 x 10 -6. MOST Kepler

5. Elliptical Orbits Semi-major axis ApocentrePericentre

6. Eccentricities of Extra Solar Planets Eccentricity Semi-major axis (AU)

7. Inclination: i=0° (face on) Orientation of the orbital plane - Inclination

8. Inclination: i=10°

9. Inclination: i=45°

10. Inclination: i~90° (edge on)

11. Argument of pericentre: ω=0° To observer Orientation of the orbital plane - Argument of Pericentre

12. To observer Argument of pericentre: ω=90°

13. To observer Argument of pericentre: ω=-90°

14. Model Reflective properties of planets based on Pioneer data of Jupiter. Planetary radius assumed to be 1 Jupiter radius. Example light curve properties: –Semi-major axis = 0.1 AU –Argument of pericentre = 60° –Eccentricity = 0.5

15. Time P days 8 x 10 -6 0 Example Light Curve i=90 o (Edge on) L P / L * PericentreApocentre

16. Time 8 x 10 -6 i=75 o 0 L P / L * P days

17. Time 8 x 10 -6 i=60 o 0 L P / L * P days

18. Time 8 x 10 -6 i=45 o 0 L P / L * P days

19. Time 8 x 10 -6 i=30 o 0 L P / L * P days

20. Time 8 x 10 -6 i=15 o 0 L P / L * P days

21. Time 8 x 10 -6 i=0 o (Face on) 0 L P / L * P days

22. Example - HD 108147b Extra solar planet discovered by Pepe, Mayor, et al (2002, A&A, 388, 632). Properties: –Semi-major axis = 0.104 AU –Period = 10.9 days –Eccentricity = 0.498 –Argument of pericentre = -41° –Inclination = ?

23. Time 10.9 days 40 x 10 -6 HD 108147b 0 L P / L *

24. Time 10.9 days 10 x 10 -6 Contrast contrast 0 L P / L *

25. Contrast for e=0 Inclination (i) 90 0 -90 Scale at 0.1 AU (x10 -6 ) 100 10 1 0.1 Argument of pericentre (ω) 090 Kepler

26. Contrast for e=0.6 Inclination (i) 90 0 -90 Scale at 0.1 AU (x10 -6 ) Argument of pericentre (ω) 090 100 10 1 0.1

27. Contrast for various e Argument of pericentre (ω) Scale at 0.1 AU (x10 -6 ) Inclination (i) e=0.6 e=0.7 e=0.8 e=0 e=0.1 e=0.2 e=0.3 e=0.4 e=0.5 100 10 1 0.1

28. Conclusions 1.A low inclination (face on) orientation can show strong contrast if it has a high eccentricity orbit. 2.Light curves from elliptical orbits may help constrain a systems inclination. 3.Favourable pericentric orientation can dramatically increase the contrast.