1. the brightest stars do not live alone
Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce
Selma E. de Mink
Hubble Science Briefing , February 7, 2013
Hubble Fellow at Space Telescope Science Institute / Johns Hopkins University

2. the brightest stars are up to a million times brighter than the Sun
are rare
Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce
live fast and die young
are embedded in clouds of gas & dust
are very hard to study 2

3. This is what we thought …
Massive Stars*
BOOM
Low-mass
Stars
*8-150 times more
massive than the sun
…. but it turns out that it is not that simple 3

4. Some stars are Single 4

5. 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)
Credit: sdowww.lmsal.com, maps.google.com 5

6. many stars are quite unlike the Sun
Artist impression: (ESO/L. Calçada/Nick Risinger)
Photo: S. Brunier/ESO.
Two stars, each nearly as bright as the other, circle around it, every eighty years. They come within 1.7 billion kilometres of each other, and are 5.3 billion kilometres from each other at their maximum distance apart. Alpha Centauri A and B are practically twin sisters of the Sun.
Alpha Centauri, our nearest neighbor, is a multiple system: Star A & B orbit each other every 80 years 6

7. another famous multiple
Alcor & Mizar
Credit: J. Benson et al., NPOI Group, USNO, NRL
Image Credit: ESO Online Digitized Sky Survey 7

8. 3 binaries forming a sextuple system
Alcor A & B
Mizar A: a & b
Mizar B: a & b A
Spectroscopic binary
Zimmerman et al. 2009
Credit: J. Benson et al., NPOI Group, USNO, NRL
Image Credit: ESO Online Digitized Sky Survey
Mizar A & B 8

9. 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

10. Not every binary is equal
Close Binary System
Closer than the distance from the Sun to Mars.
One orbit takes between a day and few years.
Wide Binary System
Wider than the distance from the Sun to Jupiter.
One orbit takes a few years up to centuries or more. 10

11. Close binary stars 11

12. A typical star becomes about 100-1000 times bigger during its life …12

13. =
Therefore, stars in close binary systems will interact 13

14. Artist Illustration of a “vampire star system”: ESO: Calçada/Kornmesser/de Mink14

15. Questions so far? 15

16. How many stars are in such close binaries?16

17. Six young star clusters17

18. Using the Doppler effect to find binaries18

19. 19

20. 20

21. How many stars are in such close binaries?21

22. What % of massive stars will interact22
Sana & de Mink et al. Science, Cartoons: de Mink / Buunk

23. It is not this simple … Massive Stars* Low-mass Stars BOOM
See video: 23

24. Bonus: cool things that binaries do24

25. make fast rotating runaway stars25

26. Conclusion 26

27. the brightest stars do not live alone
Background Design E. Buunk / S.E. de Mink, HST image: NASA Paresce
Science 27 July 2012:
Vol. 337 no. 6093 pp
Selma E. de Mink
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