New Worlds: Detection of Exoplanet systems Bryce Carande October 29, 2010 Astrophysics 591

Exoplanets: Outline Relation to Decadal survey How do we find Exoplanets? Methods of detection Useful Observatories (current and forthcoming) Spotlight: Gleise 581 system History of discoveries Mayor 2009 (4-planet solution) Vogt 2010 (6-planet solution) Gleise 581g 12/1/2018 Astrophysics 591 Carande

Exoplanet science Burgeoning field: drastically advanced in the last decade Discoveries often limited only by observation time http://brucegary.net/X/x.htm 12/1/2018 Astrophysics 591 Carande

Decadal survey for Astronomy and Astrophysics 3 Science objectives: Cosmic Dawn, New Worlds, Physics of the Universe 3 scales of space missions to accomplish objectives: Large, medium, small 12/1/2018 Astrophysics 591 Carande

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Detection methods Radial Velocity Transit Direct Imaging Interferometry Gravitational Lensing Astrometry 12/1/2018 Astrophysics 591 Carande

Radial Velocity Method Measure Doppler shift of light due to star’s perturbed motion Can only detect motion along radial axis i Orbital plane of system Planet with mass m Effect of planet on our observed Radial Velocity: = m sin(i) 12/1/2018 Astrophysics 591 Carande

Observatories for Exoplanets Current New Earth-based Keck (Hires) Ten meter telescope or Giant Magellan Telescope La Silla (3.6m) European Extremely Large Telescope Space-based Hubble JWST Kepler Darwin Corot Terrestrial Planet Finder * Very incomplete 12/1/2018 Astrophysics 591 Carande

Gleise 581: The star M-dwarf type star (.31 solar mass) 20.3 light years from Earth Sub-solar Metallicity (-.25 to -.33) Relatively ‘quiet’ star No indications of strong B-field 12/1/2018 Astrophysics 591 Carande

Gleise 581’s history of planets Year Lead Author Group Data set Planets Discovered Notes 2005 Bonfils HARPS 20 B (15.7 M⊕) Hot Neptune 2007 Udry 50 C (5.03 M⊕) D (7.7 M⊕) C: lowest mass to date, “most Earthlike”, inner edge of habitable zone Selsis, others - C: likely too hot for HZ D: could host liquid water given thick greenhouse atmosphere 2009 Mayor 119 E (1.9 M⊕) D: orbit revised to be closer; now within HZ 2010 Vogt HIRES 119+122 F (7.0 M⊕) G* (3.1 M⊕) Confirms previous results G: Terrestrial planet in HZ! *unconfirmed 12/1/2018 Astrophysics 591 Carande

Equipment: ESO 3.6m telescope in La Silla Observatory, Chile The HARPS search for southern extra-solar planets XVIII. An Earth-mass planet in the GJ 581 planetary system (2009) M. Mayor1, X. Bonfils2,3, T. Forveille2, X. Delfosse2, S. Udry1, J.-L. Bertaux4, H. Beust2, F. Bouchy5, C. Lovis1, F. Pepe1, C. Perrier2, D. Queloz1, and N. C. Santos1,6 http://www.eso.org/public/archives/images/screen/ib-la-silla05.jpg Equipment: ESO 3.6m telescope in La Silla Observatory, Chile HARPS = High accuracy radial velocity planet searcher Discovered 75 exoplanets during original 5 year mission (out of 400 known) - Bimodal distribution of planet masses: super earths (<10 Me) and gas giants (>30 Me) Focused on nearby M-dwarf stars 12/1/2018 Astrophysics 591 Carande

The HARPS search for southern extra-solar planets XVIII The HARPS search for southern extra-solar planets XVIII. An Earth-mass planet in the GJ 581 planetary system Complete Signal corrected for b corrected for b,c corrected for b,c,d corrected for all e (3.15d) b (5.63d) c (12.9d) e 59d? 67d? 82d? d: 12/1/2018 Astrophysics 591 Carande

The HARPS search for southern extra-solar planets XVIII The HARPS search for southern extra-solar planets XVIII. An Earth-mass planet in the GJ 581 planetary system 12/1/2018 Astrophysics 591 Carande

Fit 6 planets to data Equipment: Keck telescope with HIRES instrument The Lick-Carnegie Exoplanet Survey: A 3.1 M⊕ Planet in the Habitable Zone of the Nearby M3V Star Gliese 581 Steven S. Vogt1, R. Paul Butler2, E. J. Rivera1, N. Haghighipour3, Gregory W. Henry4, and Michael H. Williamson4 Equipment: Keck telescope with HIRES instrument 122 RV measurements over 11 years Combined measurements with HARPS data Fit 6 planets to data Confirmed previous planets; added 2 more 12/1/2018 Astrophysics 591 Carande

Periodogram Also did reverse process: Start with 6-planet solution Re-combine each planet back into data set See if discernable peaks arise -> HARPS data alone insufficient to detect g 12/1/2018 Astrophysics 591 Carande

Combined data sets 12/1/2018 Astrophysics 591 Carande

http://en.wikipedia.org/wiki/File:Gliese_581_system_compared_to_solar_system.jpg

Implications for η⊕ Fraction of planets within a habitable zone 581g makes number 2 302 dwarf type stars within 10pc Only 10 of these have more than 200 RV observations (incompleteness factor) η⊕ = (2 / 302)*(302/10) = 20% 12/1/2018 Astrophysics 591 Carande

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