Multiple, Coeval and Hubble-like bipolar outflows Romano L.M. Corradi Isaac Newton Group of Telescopes La Palma, Spain

Multiple, Coeval and Hubble-like

bipolar outflows

Romano L.M. Corradi

Isaac Newton Group of Telescopes

La Palma, Spain

He 2-104 Corradi et al. 2001 ApJ 553, 221

HST [NII] May 1999

inner lobes outer lobes

polar jets

Spatiokinematical modelling

Axisymmetrical heuristic model with expansion velocity that is• radially directed• time-independent (no acceleration)• latitude-dependent (parametrized in some way, e.g. Solf & Ulrich

1985, A&A 148, 274)

These models produce structures that grow self-similarly in time,

in a “Hubble-like flow” ( Vexp r )

Inner lobesVmax = 20 km s-1

Veq = 6 km s-1

i = 58o

age = 5700 yr (D=4.4 kpc)

Outer lobesVmax = 120 km s-1

Veq = 12 km s-1

i = 58o

age = 5700 yr

Polar jets( i = 58o)V = 240 km s-1

age = 5300 yr

Results for He 2-104

• Streamlines are radial and gas is expanding at constant velocity

in a Hubble-like flow

• The multiple outflows (two nested bipolars + jet) are coeval

Not associated with recurrent nova-like explosions

New scenario for their formation is needed!

Multiple bipolar outflows

• Among “large” “PNe”: NGC 2440, Mz 3, He 2-104, M 2-9, MyCn 18, M 2-46, K 3-24, M 1-75 (Manchado et al. 1996, ApJ 466, L95).

Maybe few more, but clearly having multiple lobes is not a common phenomenon in evolved PNe.

• For PPNe and young PNe, see e.g. Sahai’s talk : “Most PPNe are multipolar” (e.g. Sahai 2003 RMexAA Conf. Ser. 15, 17)

e.g. He 2-47, M 1-37, CRL2688, Rob 22, He 2-180, AFGL 618,…

Multiple bipolar outflows

• Why multipolar outflows are so common in PPNe but not in PNe? Photoionization smooths asymmetries? (but not for massive stars)

•Do/which multipolar PPNe evolve into multiple bipolar PNe (“jets blowing bubbles” Soker 2002, ApJ 568, 726)? None (how many

symbiotic stars are misclassified as bipolar PNe)?

• Which is the origin and the role of each of the [multiple and intermittent] fast winds in bipolar PNe and PPNe? Are they produced during recurrent outbursts in interacting binary systems? (This does not seem to be the case of He 2-104!)

Are multiple outflows coeval?

• He 2-104 yes (two pairs of lobes + polar jet)

• Mz 3 almost (lobes/columns), no (lobes-columns / rays)

(Santander’s talk)

• M 2-46 almost (two pairs of lobes, some 30% age difference) (Manchado et al. 1996, ApJ 466, L95)

• PPNe likely?

Detailed kinematical data and modelling for more PNe is needed!

Hubble-law in highly collimated PNe

• He 2-104 tkin~6000 yr (but distance very uncertain!)

• Mz 3 tkin~1000-1500 yr (Santander’s talk)

• NGC 6537 tkin~3000 yr (Corradi & Schwarz 1993, A&A 269, 462)

• Sa 2-237 tkin~600 yr (Schwarz et al. 2002, ApJ 565, 1084)

• He 2-36 tkin~1800 yr (Corradi & Schwarz 1993, A&A 273, 247)

• Mz 1 tkin~7000 yr (Marston et al. 1998, A&A 329, 683)

• M 2-46 tkin~7500-10000 yr (Manchado et al. 1996, ApJ 466, L95)

• …

Vexp radius (no shaping!)

Snapshot modelo

Mz 3

Santander’s talk


• He 2-104 tkin~6000 yr







• …


NGC 6537


• He 2-104 tkin~6000 yr







• …


Deviations from Hubble-law in bipolar PNe

• M 2-9 (constant radial velocity at all points in the lobes)

• Hb 5? (tkin~700 yr)

(Corradi & Schwarz 1993, A&A 269, 462)

• MyCn 18? (Vexp r 0.60.4) (Dayal et al. 2000, AJ 119, 315)

Few cases!

Hubble-like flows are commonly found in bipolar PNe

Deviations from Hubble-law in bipolar PNe• polar protrusions in the lobes of Mz 3

• The same in NGC 3918?

Corradi et al. 1999 ApJ 523 721

Kastner et al. 2003 ApJ 591 L37

The “Hubble-law” is predicted by the GISW models if the two

interacting winds have constant properties: then Vexp becomes a

constant with time and the flow reaches an asymptotic shape.

However, the self-similar regime might not be reached because of

the time variations of the wind properties.

Timescales to reach the self-similar regime depends on winds

parameters and geometry.

( Icke et al. 1992, AJ 97, 462; Dwarkadas et al. 1996, ApJ 457, 773)

Observations show that the self-similar regime is indeed reached

in few thousand years in bipolar PNe, and possibly even earlier.

(better knowledge of distances is needed)

Comparison with the GISW theory

Conclusions

• Multiple bipolar outflows are not common in PNe (contrary to

PPNe), and might be related to misclassified objects (e.g.

symbiotic stars). The path from bipolar PPNe to bipolar PNe is

not clear.• More kinematical data are needed to test how often coeval

bipolar outflows (as in He 2-104) are produced. New ideas are

needed to explain them.• Hubble-like flows are a common characteristic of bipolar PNe

with kinematical ages of few thousand years, as predicted by the

GISW, but also likely of younger objects. Is the actual shaping of

bipolar PNe done on a very short timescale?

Documents

Multiple, Coeval and Hubble-like bipolar outflows Romano L.M. Corradi Isaac Newton Group of Telescopes La Palma, Spain