the brightest stars do not live alone
Background Design E. Buunk / S.E. de Mink, HST im
age: NASA Paresce
Selma E. de MinkHubble Science Briefing , February 7, 2013
Hubble Fellow at Space Telescope Science Institute / Johns Hopkins University
the brightest stars
are embedded in clouds of gas & dust
are up to a million times brighter than
the Sun
live fast and die young
are rare
are very hard to study
Background Design E. Buunk / S.E. de Mink, HST im
age: NASA Paresce
2
This is what we thought …
Massive Stars*
Low-mass Stars
BOOM
*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 starIf the Sun were the size
of a baseball …
… the nearest star would be in Houston, TX (1,400 mi. away)
… in Yankee stadium…
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
Image Credit: ESO Online Digitized Sky Survey
Alcor & Mizar
7
3 binaries forming a sextuple system
Image Credit: ESO Online Digitized Sky Survey
Zimmerman et al. 2009
Spectroscopic binary
Alcor A & B
Mizar A & B
Mizar A: a & b Mizar B: a & b
8
A
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
• 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
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 1 2 3 4 5 6 7 8 9 10
0 500 1000 1500 2000 2500 3000 3500 4000
Number of days tocomplete one orbit 19
0 1 2 3 4 5 6 7 8 9 10
0 500 1000 1500 2000 2500 3000 3500 4000
Number of days tocomplete one orbit 20
How many stars are in such close binaries?
21
What % of massive stars will interact
Sana & de Mink et al. Science, Cartoons: de Mink / Buunk22
It is not this simple …
Massive Stars*
Low-mass Stars
BOOM
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
the brightest stars do not live alone
Background Design E. Buunk / S.E. de Mink, HST im
age: NASA Paresce
Selma E. de MinkScience 27 July 2012:
Vol. 337 no. 6093 pp. 444-446
More information: http://hubblesite.org/newscenter/archive/releases/2012/33/full/
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