1. The Smallest Planet Orbiting the Smallest Star David Bennett University of Notre Dame for the MOA & OGLE Collaborations mobile phone: 574-315-6621

2. Summary of Finding MOA-2007-BLG-192Lb is a ~3 Earth-mass planet –this is the smallest discovered to date Its host star has a mass of 6  3% of the mass of the Sun –Most likely, it is < 8% of a Solar mass, which is too small to sustain nuclear reactions - a brown dwarf The system is at a distance of 3000 light years The planet’s orbital radius is about the same as that of Venus (70% of the Earth-Sun distance) David Bennett - Smallest Planet Orbits Smallest Star

3. Host Color Is Probably Magenta “Brown” Dwarfs are magenta Adam Burrows et al (2001) (520-603-3297) due to atmospheric absorption by Sodium and Potassium David Bennett - Smallest Planet Orbits Smallest Star

4. Possibly a Low-Mass Red-Dwarf Star Future observations with the Hubble Space Telescope or the European Southern Observatory’s Very Large Telescope will decide this issue. David Bennett - Smallest Planet Orbits Smallest Star

5. The Microlensing Method Uses a background star as a source of light Gravitational field of star and planet act as a lens requires no light from the planetary host Observed signal is changing magnification Required alignment is very rare, so the very dense Galactic bulge fields are observed David Bennett - Smallest Planet Orbits Smallest Star

6. Source Star Moves Across Lens Magnification Pattern Observed brightness changes as source star crosses lens system magnification pattern. (credit: Fumio Abe, MOA Collaboration) David Bennett - Smallest Planet Orbits Smallest Star

7. Observed Light Curve planetary signal captured by MOA due to new wide field-of-view telescope and camera David Bennett - Smallest Planet Orbits Smallest Star

8. New MOA Telescope Enabled Discovery 1.8m MOA-2 telescope –Mt. John Observatory, NZ MOA-cam3 CCD Camera –Images 2.2 sq. deg. –13 times the area of the full moon Entire Galactic Bulge imaged every hour –All microlensing events monitored for planets Similar telescopes are needed in Chile (OGLE- IV) and South Africa David Bennett - Smallest Planet Orbits Smallest Star

9. Comparison to Other Exoplanets Microlensing discoveries in red, transit discoveries in blue and Doppler discoveries in black. Letters indicate Solar System planets. The snow-line relates to the conditions David Bennett - Smallest Planet Orbits Smallest Star snow at t = 1 Myr steam at t = 1 Myr

10. Credits & Further Info for further info, contact David Bennett (cell phone: 574-315-6621) or go tohttp://www.nd.edu/~bennett/moa07blg192/ Scientific Paper to be published in the Astrophysical Journal (arXiv:0806.0025) Authors: D.P. Bennett 1, I.A. Bond 1, A. Udalski 2, T. Sumi 1, F. Abe 1, A. Fukui 1, K. Furusawa 1, J.B. Hearnshaw 1, S. Holderness 1, Y. Itow 1, K. Kamiya 1, A.V. Korpela 1, P.M. Kilmartin 1, W. Lin 1, C.H. Ling 1, K. Masuda 1, Y. Matsubara 1, N. Miyake 1, Y. Muraki 1, M. Nagaya 1, T. Okumura 1, K. Ohnishi 1, Y.C. Perrott 1, N.J. Rattenbury 1, T. Sako 1, To. Saito 1, S. Sato 1, L. Skuljan 1, D.J. Sullivan 1, W.L. Sweatman 1, P.J. Tristram 1, P.C.M. Yock 1, M. Kubiak 2, M.K. Szymanski 2, G. Pietrzynski 2, I. Soszynski 2, O. Szewczyk 2, L. Wyrzykowski 2, K. Ulaczyk 2, V. Batista 3, J.P. Beaulieu 3, S. Brillant 3, A. Cassan 3, P. Fouque 3, P. Kervella, D. Kubas 3, and J.B. Marquette 3 1 MOA Collaboration 2 OGLE Collaboration 3 PLANET Collaboration US effort funded by the NSF and NASA David Bennett - Smallest Planet Orbits Smallest Star