STScI Workshop on

Massive Stars8 - 11 May 2006

Baltimore

Multiplicity of Massive Stars -Clues and Consequences

Hans Zinnecker (AIP, Potsdam, Germany)

goal of this short contribution

- remind you of high incidence of binaries,triples, and Trapezium systems

- remind you of preponderance of close massive binaries(SB2, SB1, eclipsing binaries)

- new idea to explain the origin of Trapezium systems

- new idea to explain the origin of the close binaries

goal of this short contribution (ctd.)

- Example: The Orion Trapezium Cluster(origin and future evolution)

- Question: seperations and mass ratiosfor massive close binariesto become ``interactive´´?(case A, B, C mass transfer)

RLOF: mass / A.M. accretion efficiency?LBV: violent mass loss (stellar wind),

onset at which initial stellar mass?

stellar rejuvenation? population synthesis!

HST image

1’’

0.5’’

B2

B3

B4

B1

sep = 38 mas

0.05’’

**

C2

C1

0.1’’

A2

A1

sep = 215 mas

B2-3:sep = 117 mas

1997.8

2001.2

10 AU

1999.1

1998.8

High-resolutioninfrared speckle reconstruction

2003.8

Schertl et al. (2003, A&A)

Young, massive Orion Trapezium multiples:

orbital motion, stellar masses, & ages

other relevant considerations (not today)

- formation clues from observed multiplicity trendsin different stellar environments

- consequences of multiplicities for runaways,non-local supernovae, starburst population synthesisincluding exotic products of binary stellar evolution(high mass X-ray binaries, binary pulsars, TZ-objects)

outline of this talk- quick summary of multiplicity observations for massive stars (spectroscopic, speckle, adaptive optics, HST/FGS observations)

- example: the multiplicities of the Orion Trapezium stars and the companion star frequency of high-mass vs. low-mass stars

- SPH simulations: hierarchical star cluster formation and the merging of subclusters as a model for the origin of Trapezia

- origin due to formation or early dynamical N-body evolution (accretion onto low-mass binary, hardening of a wide-binary)

outline of another talk (not today)

- massive binaries in different stellar environments: young clusters rich and poor, OB associations, runaway stars

- stellar evolution of massive tight binaries (RLOF; mergers) high-mass X-ray binaries, supernova kicks, gamma-ray bursts

Some References

- Bonnell and Bate (2005): MNRAS 362, 915- Langer et al. (2003), IAU-Symp. 212- Mason et al. (1998), AJ 115, 821- Mermilliod/Garcia (2001), IAU-Symp. 200 - Petrovic et al. (2005), A&A 435, 1013- Portegies Zwart (2001), IAU-Symp. 200- Preibisch et al (2001), IAU-Symp. 200- Van Bever & Vanbeveren (1998), A&A 334, 21- Zinnecker (2003), IAU-Symp. 212- Zinnecker (2006): Sacacomie Proc.- Zinnecker (2006): Tartu Proc.- Zinnecker (2006): ESO Workshop Proc.

García, B. & Mermilliod, J. C. 2001, A&A 368, 122

Brown, A. G. A. 2001, AN 322, 43

A Trapezium system in M16?

McCaughrean, M. J. &Andersen, M. 2002, A&A 389, 513

HST image

1’’

0.5’’

B2

B3

B4

B1

sep = 38 mas

0.05’’

**

C2

C1

0.1’’

A2

A1

sep = 215 mas

B2-3:sep = 117 mas

1997.8

2001.2

10 AU

1999.1

1998.8

High-resolutioninfrared speckle reconstruction

2003.8

Schertl et al. (2003, A&A)

Young, massive Orion Trapezium multiples:

orbital motion, stellar masses, & ages

Definition ``massive´´ (primary)

stellar mass M* > 10 solar massesspectral type earlier than B2main sequence lifetime < 10 Myr

Definition ``multiplicity´´

binaries (EB, SB, VB)hierarchical triples / quadruplesTrapezium-type systems

Definition ``Multiplicity´´or companion star fraction (csf)

QTBSQTBcsf

32

Reipurth & Zinnecker 1993, A&A 278, 81

e.g. csf = 1.5 for Trapezium stars

* 1 single* . 1double* . . 1 triple* . : 1 quadruple

PS. csf = 0.5 for low-mass stars (T Tauri stars)in Orion Nebula Cluster

Origin of the Trapezium Cluster

via

hierarchical merging of subclusters

Bonnell, I. A.; Bate, M. R.; & Vine, St. G. 2003, MNRAS 343, 413

SPH simulations of a 1000 Msun turbulent mol. cloud

dynamical and binary stellar evolutionof the Trapezium Cluster (next 30 Myr)

dynamical ejections of massive stars(cf. AE Aurigae and Columbae)

close binary evolution of massive stars(future of Theta-1 Ori C, A, B binaries?)

Hoo

gerw

erf, 

R.;

de B

ruijn

e, J.

 H. J

.; de

 Zee

uw, P

. T.

2001

, A&

A 3

65, 4

9

Origin of close binary systems

(Bonnell & Bate 2005)

Idea:wide low-mass binary

mass + A.M. accretion

close high-mass binary

Origin of close binary systems

Another (older) idea:

shrinking (hardening)of wide high-mass binary systems

by close stellar encountersin dense clusters

(energy exchange in multiple systems)

Future stellar evolutionof the close binariesin the Orion Trapezium Cluster

Case A mass transfer: P ~ 10 dCase B mass transfer: P ~ 100 dCase C mass transfer: P ~ 1000 d

WR/O-stars, RSG, SN II, HMXB?

Theta-1-A 16 + 2 Msun, sep = 1 AUTheta-1-B 7 + 3 Msun, sep = 0.13AUTheta-1_C 40 + 5 Msun, sep = 16 AU

Theta-2-A 25 + 8 Msun, sep = 0.5 AUNu Ori 14 + 3 Msun, sep = 0.35AU

Iota Ori 21 + 17 Msun, sep =? Ecc.!

Other observational resultsfor other young star clusters:

S255-IR, NGC3603, R136, ...

Zinnecker, Correia, Stecklum et al. 2005, in prep.

Stolte, A.; Brandner, W.; Brandl, B.; Zinnecker, H.;Grebel, E. K. 2004, AJ 128, 765

Stolte, A.; Brandner, W.; Brandl, B.; Zinnecker, H.;

Grebel, E. K. 2004, AJ 128, 765

Moffat, A. F. J.; Drissen, L.; Shara, M. M. 1994, ApJ 436, 183

Hofmann, K.-H. & Weigelt, G. 1986, A&A 167, L15

Weigelt, G.; Baier, G. 1985, Massey, Ph.; Hunter, D. A. 1998, A&A 150, L18 ApJ 493, 180

Massey, Ph.; Penny, L. R.; Vukovich, J. 2002, ApJ 565, 982

Apai, D.; Bik, A.; Kaper, L.; Henning, Th.; Zinnecker, H. in prep.

Bosch, G.; Selman, F.; Melnick, J.; Terlevich, R. 2001, A&A 380, 137

Conclusions---------------

1) Some of the most exciting cosmic phenemena due to the presence of massive close binaries

2) Studies of star forming regions & young clusters allow us to observe binary parameter

distributions

give extra info on massive star formation provide I.C. for models of interacting binary evol

3) We all need to learn more about binary evolution!

4) Orion and other nearby clusters as starting point

Conclusions (ctd.)

4) Dynamical interactions also important (ejections, runaway stars) and generally underestimated…

5) Orion Trapezium cluster and other nearby young clusters as a starting point (link I.C. to evolutionary consequences)

PS. Watch out for ARAA review on massive star formation in preparation by YORKE & ZINNECKER 2007

consequences

a) implications of high-mass multiplicity

derive stellar masses (eclipsing SB2)correct upper IMF slope (steepening)

correct cluster vel. dispersion (dyn. mass)origin of runaway OB stars (ejection)

high-mass X-ray binaries (stellar mass BH)colliding winds, orbital drag & decay

effect on WR & SN-II progenitor massesdistance determination using eclipsing SB2

consequences

b) questions related to multiplicity

very massive stars (M > 100 Mo)through binary mergers?

multiplicity of isolatedmassive stars in the field?

multiplicity and stellar rotationof the components?

multiplicity in low-metallicityenvironments (LMC / SMC)?

multiplicity among massive stars

M > 8 M

SpT earlier B2conclusions:

1) Trapezia within Orion Trapezium

2) preponderance of tight binariesSB1: q 1 lower massesSB2: q = 1 higher masses

3) 20 out of 25 O-stars are triple, consisting of SB + VB pairs (Mason)

4) multiplicity among massive stars higher than among low-mass (3x)

WHY? gravitational dynamics