Proxima b: The Alien World Next Door - Is Anyone Home? Edward Guinan Biruni Observatory Dept. Astrophysics & Planetary Science th 40 Anniversary Workshop Villanova University 12 October, 2017
[email protected] Talking Points i. Planet Hunting: Exoplanets ii. Living with a Red Dwarf Program iii. Alpha Cen ABC -nearest Star System iv. Proxima Cen – the red dwarf star v. Proxima b Nearest Exoplanet vi. Can it support Life? vii. Planned Observations / Missions Planet Hunting: Finding Exoplanets A brief summary For citizen science projects: www.planethunters.org Early Thoughts on Extrasolar Planets and Life Thousands of years ago, Greek philosophers speculated… “There are infinite worlds both like and unlike this world of ours...We must believe that in all worlds there are living creatures and planets and other things we see in this world.” Epicurius c. 300 B.C First Planet Detected 51 Pegasi – November 1995 Mayer & Queloz / Marcy & Butler Credit: Charbonneau Many Exoplanets (400+) have been detected by the Spectroscopic Doppler Motion Technique (now can measure motions as low as 1 m/s (3.6 km/h = 2.3 mph)) Exoplanet Transit Eclipses Rp/Rs ~ [Depth of Eclipse] 1/2 Transit Eclipse Depths for Jupiter, Neptune and Earth for the Sun 0.01% (Earth-Sun) 0.15% (Neptune-Sun) 1.2% (Jupiter-Sun) Kepler Mission See: kepler.nasa.gov Has so far discovered 6000+ Confirmed & Candidate Exoplanets The Search for Planets Outside Our Solar System Exoplanet Census May 2017 Exoplanet Census (May-2017) Confirmed exoplanets: 3483+ (Doppler / Transit) 490+ Multi-planet Systems [April 2017] Exoplanet Candidates: 7900+ orbiting 2600+ stars (Mostly from the Kepler Mission) [May 2017] Other unconfirmed (mostly from CoRot)Exoplanets ~186+ Potentially Habitable Exoplanets: 51 (April 2017) Estimated Planets in the Galaxy ~ 50 -100 Billion! Most expected to be hosted by red dwarf stars Nomad (Free-floating planets) ~ 25 - 50 Billion Known planets with life: 1 so far.