Search for Life: Extrasolar Planets

by Robert Nemiroff Michigan Technological University

Physics X: About This Course

• Officially "Extraordinary Concepts in Physics" • Being taught for credit at Michigan Tech o o Light on math, heavy on concepts Anyone anywhere is welcome • No textbook required o o Wikipedia, web links, and lectures only Find all the lectures with Google at:  "Starship Asterisk" then "Physics X" o o http://bb.nightskylive.net/ asterisk/viewforum.php?f=39

Search for Extrasolar Planets

If life exists outside of Earth, it is likely on a planet.

• How common are planets around stars?

• How common are rocky planets?

• How common are planets in the habitable zone ?

o where liquid water can exist • How common is water?

• How common are biomarkers ?

Search for Extrasolar Planets

Hot topic in modern astronomy. Main techniques: • slight changes in pulsar timings o civilizations unlikely there (?)  but read Dragon's Egg by R. Forward • slight doppler wobble of star due to planets o most planets now found this way • slight occultation of planet by star o Kepler satellite will likely find thousands • gravitational lensing o once and done, but can see low mass planets • direct image of planet o hard since parent star so bright

55 Cancri: Familiar Planet Discovered Illustration Credit & Copyright: Lynette Cook APOD: 2002 June 14

Water Claimed in Evaporating Planet HD 209458b Illustration Credit: ESA, A. Vidal-Madjar (IAP, CNRS), NASA APOD: 2007 April 17

A Dangerous Sunrise on Gliese 876d Illustration Credit & Copyright: Inga Nielsen (Hamburg Obs., Gate to Nowhere) APOD: 2008 May 21

HR 8799: Discovery of a Multi-planet Star System Credit: C. Marois et al., NRC Canada APOD: 2008 November 17

Kepler's Streak Credit & Copyright :

APOD: 2009 March 9 Ben Cooper

CoRoT Satellite Discovers Rocky Planet Illustration Credit: ESO/L. Calcada APOD: 2009 September 23

Credit: A Giant Planet for Beta Pic

A.-M. Lagrange, D. Ehrenreich (LAOG), et al.

, ESO APOD: 2010 July 3

Companion of a Young, Sun-like Star Confirmed Credit:

Gemini Observatory, D. Lafreniere, R. Jayawardhana, M. van Kerkwijk (Univ. Toronto) APOD: 2010 July 4

Zarmina's World Illustration Credit & Copyright:

APOD: 2010 October 1 Lynette Cook

Kepler's First Five Exoplanets (Wikipedia)

Planets around Alpha Centauri ?

RJN comment: The Alpha Centauri system is the closest star system to the Sun, and contains a star very much like our Sun. Does this star have planets? We currently don't know. We should try harder to find out! At 4.3 light years distant, it might be a good far future outpost for humans.