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Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce the brightest stars do not live alone Selma E. de Mink Hubble Science Briefing , February 7, 2013 Hubble Fellow at Space Telescope Science Institute / Johns Hopkins University Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce the brightest stars are up to a million times brighter than the Sun are rare are embedded in clouds of gas & dust live fast and die young are very hard to study 2 This is what we thought … Massive Stars* Low-mass Stars *8-150 times more massive than the sun …. but it turns out that it is not that simple 3 Some stars are Single 4 The Sun is a single star If the Sun were the size of a baseball … … in Yankee stadium… … the nearest star would be in Houston, TX (1,400 mi. away) 5 many stars are quite unlike the Sun Artist impression: (ESO/L. Calçada/Nick Risinger) Alpha Centauri, our nearest neighbor, is a multiple system: Star A & B orbit each other every 80 years 6 another famous multiple Alcor & Mizar 7 3 binaries forming a sextuple system Alcor A & B A Mizar A: a & b Mizar B: a & b Spectroscopic binary Zimmerman et al. 2009 Mizar A & B 8 Classic definition Binary System = a system of two objects in space (usually stars), which are so close that their gravitational interaction causes them to orbit around their common center of mass. According to this definition, almost all stars are binaries (or multiples). The Sun is one of the exceptions. 9 Not every binary is equal Close Binary System Wide Binary System • Closer than the distance from the Sun to Mars. • Wider than the distance from the Sun to Jupiter. • One orbit takes between a day and few years. • One orbit takes a few years up to centuries or more. 10 Close binary stars 11 A typical star becomes about 100-1000 times bigger during its life … 12 Therefore, stars in close binary = systems will interact 13 Artist Illustration of a “vampire star system”: ESO: Calçada/Kornmesser/de Mink 14 Questions so far? 15 How many stars are in such close binaries? 16 Six young star clusters 17 Using the Doppler effect to find binaries 18 0 0 500 1000 1500 2 2000 4 2500 6 3000 Number of days to complete one orbit 8 10 3500 4000 19 0 0 500 1000 1500 2 2000 4 2500 6 3000 Number of days to complete one orbit 8 3500 10 4000 20 How many stars are in such close binaries? 21 What % of massive stars will interact 22 Sana & de Mink et al. Science, Cartoons: de Mink / Buunk It is not this simple … Massive Stars* Low-mass Stars See video: http://hubblesite.org/newscenter/archive/releases/2012/33/video/b/ 23 Bonus: cool things that binaries do 24 make fast rotating runaway stars 25 Conclusion 26 Science 27 July 2012: Vol. 337 no. 6093 pp. 444-446 Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce the brightest stars do not live alone Selma E. de Mink More information: http://hubblesite.org/newscenter/archive/releases/2012/33/full/