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/