mini-course on

Star and Planet

Formation

with, in order of appearance,

Marten van Kerkwijk

Norm Murray

Ray Jayawardhana

Aleks Scholz

Ed Thommes

Alexis Brandeker

Pawel Artymowicz

Yanqin Wu

Barnard 68

Barnard 68

Barnard 68

Barnard 68

Isothermal Spheres

Shu 1977, ApJ 214, 488

Barnard 68

Alves et al., 2001,

Nature 409, 159

Stellar Birthline

Shu et al., 1987, ARA&A 25, 23

Initial Mass Function

Luhman, 2004,

ApJ 617, 1216

Initial Mass Function

Luhman, 2004,

ApJ 617, 1216

Initial Mass Function

Luhman, 2004,

ApJ 617, 1216

... given the success of the present model in

predicting the observed shape of the stellar IMF, we conclude that

turbulent fragmentation is essential to the origin of the stellar IMF.

Turbulent Fragmentation?

Competitive Accretion?

... Star formation occurs ... via the fragmentation both of

dense molecular cloud cores and of massive stellar disks. ...

the observed statistical properties of stars are a natural consequence...

BINARIES!

Period Distribution

Duquennoy & Mayor 1991, A&A 248, 485

Mass Ratio Distribution

Duquennoy & Mayor 1991, A&A 248, 485

Only 30% single?

Companion Star Fraction

Patience et al. 1999, AJ 115, 1972

Patience et al. 1999,

ApJ 581, 654

Delgado Donate et al. 2004, MNRAS, 351, 617

Initial Multiplicity

Delgado Donate et al. 2004, MNRAS, 351, 617

Initial Multiplicity

Predictions:

80% of newborn in multiples;
down to 40% by 10 Myr.

More massive stars are more
likely to have companions.

No brown dwarfs in close orbits;
in wide orbits only around binaries

Delgado Donate et al. 2004, MNRAS, 351, 617

Multiplicity for diff. Mass

Brown Dwarf Desert

Brandeker 2003, IAUS, 221, 228

Many Multiples?

OBSERVE!

CLOSE

BINARIES!

On main

sequence

On pre-main

sequence,

up to factor

~5..10 larger!

On main

sequence

On pre-main

sequence,

up to factor

~5..10 larger!

Fission?

Unstable dynamics?

Stable dynamics?

Kozai cycles and tidal dissipation

Formation of Close Binaries

in Triple Systems?

Third star induces Kozai cycle.

(can be after stars arrive on main sequence)

Tides take over once eccentricity becomes

sufficiently high.

Prediction:

all close binaries are in triple systems!

A smaller molecular cloud in more detail, in true colour. One sees that the dust absorbs the star light efficiently. But better in the blue than in the red, which is why the stars near the edge appear `reddened'. If there were stars forming in this cloud, we couldn't see it.

Image from European Southern Observatory press release 1999/20; it was made using the Very Large Telescope (press release 1999/43).

In the infrared, dust is less efficient at blocking light, as can be seen in this image, taken at infrared wavelengths. We see in and through the clouds, and find that this particular one has no stars forming; all the ones we see are in the background.

Image from European Southern Observatory press release 1999/29. It was taken with the New Technology Telescope NTT (now not so new any more).

2004-10-05T19:40:13