1. Studying cool planets around distant low-mass stars Planet detection by gravitational microlensing Martin Dominik Royal Society University Research Fellow SUPA, University of St Andrews, School of Physics & Astronomy (Part II)

2. Bending of starlight by stars (Gravitational microlensing) SL angular Einstein radius with ‘typical’ D S ~ 8.5 kpc and D L ~ 6.5 kpc θ E ~ 600 (M/M ☉ ) 1/2 as μ ) DL DSDL DS DS−DLDS−DL θ E = ( 1/2 4GM c2c2

3. Bending of starlight by stars (Gravitational microlensing) SL (t-t 0 )/t E t E ~ 40 ( M / M ☉ ) 1/2 days

4. Notes about gravitational lensing dated to 1912 on two pages of Einstein’s scratch notebook

6. First reported microlensing event MACHO LMC#1 Nature 365, 621 (October 1993)

7. Optical Gravitational Lensing Experiment 1.3m Warsaw Telescope, Las Campanas (Chile) 1.8m MOA Telescope, Mt John (New Zealand) τ ~ 10 -6 for microlensing event → ~1000 events alerted per year daily monitor ≳ 100 million stars, Current microlensing surveys (2007)

8. Prediction from data prior to first caustic peak Text adapted from M. Dominik et al. (PLANET collaboration), 2000, P&SS 50, 299 Bending of light due to gravitational field α = 4GM c2ξc2ξ t - t 0 [d] 4GM ✶ c2c2 θ E = ) DL DSDL DS DS−DLDS−DL ( 1/2 Δmag 0.5 1 1.5 2.5 2 t E = 40 d 050-50 planetary ‘blip’ q = M p /M ✶, d = δ 0 / θ E 0 t-t 0 [d] adapted from M. Dominik et al. (PLANET collaboration), P&SS 50, 299 (2002) Planet detection by microlensing

9. 1-2% photometric precision 1.5 - 2.5 hr sampling 20 events at given time, 75 per season 6 events at given time, 20 per season bright stars (giants): fainter stars: PLANET restricted (1999): ~ 3 f J jupiters/year M. Dominik et al. (PLANET collaboration) 2002, P&SS 50, 299 http://planet.iap.fr PLANET full capability: ~ 15-25 f J jupiters/year MACHO/OGLE-II (1999): ~ 100 alerts OGLE-III/MOA (2006): ~ 1000 alerts Jupiters between 0.6 and 1.6 r E : ~ 15% detected in A 0 ≳ 1.34 events ~ 80% detected in A 0 ≳ 10 events A round-the-clock follow-up network

10. PLANET planet detection efficiency preferred:m large a ~ 1 — 4 AU R S ~ (few km) und D ~ (few kpc) gives r E = D L θ E ~ (few AU) duration Δ t and probability of signal ~ q 1/2 signal amplitude only reduced by finite angular radius θ of source star for Δ t ≲ 2 θ / μ ✶ ✶ d = δ 0 / θ E ~ 1 (“resonance”) ) DL DSDL DS DS−DLDS−DL θ E = ( 1/2 4GM c2c2 preliminary 14 most favourable events from 2004 season

11. from 42 events well-covered by PLANET 1995-1999 f > f(d,q) ruled out at 95% C.L. 1/4 1/3 1/2 2/3 3/4 M. Albrow et al. (PLANET collaboration), 2001, ApJ 556, L113 ~ jupiter- mass f < 1/3 corresponds to 9 expected none observed First planetary abundance limits

12. C. Snodgrass, K. Horne, & Y. Tsapras 2004, MNRAS, 351, 967 Cumulated planet detection efficiency q = 10 -3 q = 10 -4 m = m jup 2002 OGLE-III data - 321 events ~ 1.5 % ~ 3 % Survey detection efficiency for planets

13. OGLE 2003-BLG-235 MOA 2003-BLG-53 I. A. Bond et al. (MOA and OGLE collaborations), 2004, ApJ 606, L155 t E = 61.5 d, d = 1.12, q = 3.9 × 10 -3, t ✶ = 0.059 d θ ✶ = (0.50 +/- 0.05) μ as M ~ 1.5 M ♃ The first microlensing planet

14. A. Udalski et al. (OGLE, MicroFUN, MOA, and PLANET/RoboNet collaborations), 2005, ApJ 628, L109 OGLE 2005-BLG-071 Text close binary t E = 73.9 d d = 0.758 q = 6.7 × 10 -3 wide binary t E = 70.9 d d = 1.294 q = 7.1 × 10 -3 M ~ 3 M ♃.... and the second one

15. Text April 2004: “Earth-like planet search to start” Dominik: “If 20% of these stars are surrounded by planets, we expect to find 10-15 giant planets and one or two Earth-sized worlds within three years.” From Jupiters to Earths

16. Stellar mass probed by microlensing Ida S., Lin D. N. C., 2005, ApJ 626, 1045 Host stars and expected planet abundance

17. True-colour image composed from BVI taken with Danish 1.54m at ESO LaSilla (PLANET collaboration) OGLE 2005-BLG-390

18. Image taken with Danish 1.54m at ESO LaSilla, convolved with model light curve (animation by Daniel Kubas) OGLE 2005-BLG-390

19. J.-P. Beaulieu et al. (PLANET/RoboNet, OGLE, and MOA collaborations), 2006, Nature, in press (26-Jan) 10-Aug OGLE 2005-BLG-390 31-Jul J.-P. Beaulieu, D.P. Bennett, P. Fouqué, A. Williams, M. Dominik, and 68 others (PLANET/RoboNet, OGLE, and MOA collaborations), 2006, Nature 439, 437

20. source trajectory Einstein ring OGLE-2005-BLG-390 magnification map map by Aarno Korpela, animation by Martin Dominik

22. M p = 5.5 M ♁ (2.1), M ✶ = 0.22 M ☉ (2.1), a = 2.9 AU (1.6), P = 10.4 yr (2.0), D L = (0.85 ± 0.15) R GC μ= ✶ /t ✶ = 7 mas/yr, θ E = t E = 210 θ as μ μ R P ~ 2.4 R ♁, g P ~ 0.9 g ♁ (for ρ= ♇ ) ρ J.-P. Beaulieu, D.P. Bennett, P. Fouqué, A. Williams, M. Dominik, and 68 others, (PLANET/RoboNet, OGLE, and MOA collaborations), 2006, Nature 439, 437 M. Dominik, 2006, MNRAS 367, 669

23. Artist’s impression of OGLE-2005-BLG-390Lb © ESO

24. figure courtesy of K. Horne Exoplanet discovery space

25. microlensing transits radial velocity http://www.ibiblio.org/astrobiology (follows J. F. Kasting, D. P. Whitmire, R. T. Reynolds, 1993, Icarus 101, 108) Approaching the habitable zone

26. informal consortium, involving amateur astronomers only observe highly-promising close-alignment events OGLE 2005-BLG-169 M ~ 13 M ♁ A. Gould et al., 2006, ApJ 644, L37

27. figure courtesy of K. Horne Exoplanet discovery space (II)

28. Ida S., Lin D. N. C., 2005, ApJ 626, 1045 Distribution of planets (simulation) Microlensing detections A. Cassan, D. Kubas, M. Dominik et al. (PLANET collaboration), in preparation Average detection efficiency 14 prime events - PLANET 2004 Detections and planetary abundance

29. RoboNet 1.0 http://www.astro.livjm.ac.uk 2.0m robotic telescopes, funded by Common PLANET/RoboNet microlensing campaign since 2005

30. 5.5 M ♁ 1 M ♁

31. simulated data t E = 11.0 d d = 1.61 u 0 = 0.359

32. simulated data

33. t E = 11.0 d d = 1.61 u 0 = 0.359 simulated data t E = 11.0 d d = 1.61 u 0 = 0.359

34. simulated data t E = 11.0 d d = 1.61 u 0 = 0.359

35. t E = 11.0 d d = 1.2 u 0 = 0.359 Planet with 0.1 Earth masses

36. Microlensing live continue light curve plotter SIGNALMEN Optical Gravitational Lensing Experiment RoboNet 1.0

41. Future projects (I) Automated Robotic Terrestrial Exoplanet MIcrolensing Search M. Dominik, K. Horne, A. Allan, N.J. Rattenbury, Y. Tsapras, C. Snodgrass et al. A possible expert-system based cooperative effort to hunt for planets of Earth mass and below

42. Future projects (II) GAlactic BAR Infrared Time-domain Survey (GABARIT) A UKIRT Large Project Proposal E. Kerins et al.

43. Planets detected by microlensing ( )20072008200920102006 NOT The End