HH 24: Multiplicity and Jet Formation Bo Reipurth Institute for - PowerPoint PPT Presentation

HH 24: Multiplicity and Jet Formation Bo Reipurth Institute for Astronomy University of Hawaii

Notwithstanding, in this talk I will argue that if we do not understand binary formation we do not understand star formation.

Larson’s conjecture: all stars are formed in unstable systems that break up, forming the field star population The multiplicity frequency declines through the protostellar and pre-main sequence phases due to breakup of small multiple systems

Disintegration of Multiple Systems • • Non-hierarchical systems are unstable and oscillate between two phases: interplay and close triple approach , and the latter can lead to ejection . Reipurth 2000

Numerical Simulations • Code developed by Seppo Mikkola in Turku • Newborn triple system inside cloud core • Stars gain mass through Bondi-Hoyle accretion • Cloud core loses mass from accretion to stars and from evaporation • Extinction of stars calculated continuously Reipurth et al. 2010

Only two stars are seen, because the binary is unresolved on this scale One second of the movie corresponds to 30,000 years

A sample of 100 simulations of three 0.5 Msun stars with initial mean separations of 100 AU emerging from a 3 Msun core Red: ejections leading to escapes Blue: ejections that remain bound Numerous stellar seeds escape very early, producing brown dwarfs

A sample of 100 simulations of three 0.5 Msun stars with initial mean separations of 100 AU emerging from a 3 Msun core Class 0 Class 1 Prediction: Excess of wide companions at early ages Red: ejections leading to escapes Blue: ejections that remain bound

Do we see an excess of distant companions around embedded young stars? Samples of near-infrared adaptive optics observations of newborn embedded stars Connelley et al. 2008

The answer is ‘YES’ Binary separation distribution function 2000 AU 5000 AU

The number of distant companions decreases with age: they are released once the envelopes are dispersed Spectral index is a proxy for age

Orphaned Protostars An ‘orphan’ is a protostar which has been ejected from deep inside its nascent cloud core. This ejection may be into a loosely bound orbit, which will (briefly) bring it back into the core, or into an escape. By identifying orphans, we are thus able to directly observe a protostar at near-infrared or even at optical wavelengths! T Tauri itself is a prime example of an orphaned protostar

L1630 HH 24 1 hr Ha + 1 hr [SII] with Subaru 8m telescope

Six jets G C J E X L Subaru Ha - [SII]

HH 24 with HST Dominant emission is [FeII] 1.65 micron Outflow cavities Destruction of cloud core STScI

The many jets in the HH 24 complex are driven by a non-hierarchical multiple system of at least 6 embedded protostars . This is a situation we would expect should lead to a number of very low mass orphans. Class 0/I sources S HST K-band Stellar density 1000 times that Gemini JHK in the center of a globular cluster

Single Spectroscopic binary Wide binary AU Single 5 arcsec Single Single

Ha1 Ha2 Loosely tethered orphaned protostars Ha3 and brown dwarfs Ha4 Ha5

850 micron Loosely tethered Ha1 Ha2 orphaned protostars Ha3 Orphans located far outside and proto brown dwarfs the dense cloud core are located far outside the dense cloud core Ha4 Ha5 Data from Kirk et al. 2016

Binaries from triple decays have highly eccentric orbits Courtesy Moeckel & Bally If a companion moves in an eccentric orbit it can lead to serious disturbance of the disk Disk disturbances lead to sudden increases in accretion onto the star Accretion again leads to mass loss and outflow activity

The close fly-by of a star induces mass and angular momentum loss in protoplanetary disks. This is shown here for the case of a 1 M ⊙ star surrounded by a 100 AU disk encountered by another star with 1 M ⊙ and an encounter periastron of 100 AU. Courtesy Susanne Pfalzner

Only a minor part of the disk reaches escape speed and it soon reassembles Because of such interactions the binary starts to spiral in Courtesy Susanne Pfalzner

HH jet structure and binary evolution Triple disintegration event First periastron passage Binary in-spiral phase Spectroscopic binary? Merger? FUor eruption?

Knots are not regularly spaced at each periastron passage because disk needs to reassemble 5” HH 24 jet E HST [FeII] 1.65 micron

HH 24 ALMA channel maps in H2CO V_hel 8 - 12 km/s Each panel is color coded with velocity Reipurth, Bally et al., in prep.

ALMA Field of View 09:4 km/s 12.18 12.35 12.01 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

H2CO 09:4 km/s 12.18 12.35 12.01 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 11.67 11.84 11.51 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 11.17 11.34 11.00 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 10.67 10.84 10.50 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 10.16 10.33 10.00 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 9.66 9.83 9.49 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 9.16 9.33 8.99 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 8.65 8.82 8.49 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5

09:4 km/s 8.15 8.32 7.98 45.0 50.0 55.0 -0:10:00.0 05.0 10.0 15.0 09.5 5:46:09.0 08.5 08.0 07.5