1

*

PulsarV=5-50 AU/yrCNM

How do we observe AU-scale structure? Pulsars, and optical depth imaging against extended radio continuum sources….

Epoch 1Epoch 2

2

Equivalent width variations

• EW = 0 within 2 for:0823, 1133,1737, 2016• EW0 for 1929• TSAS: L=5-50AU, n~104 cm-4, P~106 cm-3 KStanimirovic, Weisberg et al. (2010)

3

PSR at~330pc*

Welsh et al. (2010)

• Distance=350 pc, closest in the sample

• ½ of LOS inside the Local Bubble.

• HD178125 and HD180555 show NaI absorption as similar velocity TSAS is within the LB!

• LOS to B1929+10 pierces the LB wall for 50-60 pc.

• Many diffuse clouds in this direction (Aquila Rift) condensing out of the LB wall or ablated nearby molecular gas

• TSAS Tspin = 150-200 K

• CNM/WNM ratio = only 7%

TSAS properties/production influenced by the history/evolution of the Local Bubble

What’s going on with B1929+10 ?

4

• With different sources, essentially continuous coverage.• No observed power-law turbulent spectrum on scales: 1 to ~1000 AU.

Kendall’s tau test for censored data: P(no correlation) ~60%• Inhomogeneity in Galactic distribution of TSAS + v.f.f.<~1%• TSAS is not pervasive.• If TSAS is tracing the end-scales of turbulence then turbulence may dissipate

in bursts or active pockets, or it dissipates very fast.

Does the power spectrum

extend down to AU-scales?

Low optical depth

High optical depth

* : interferometricother: pulsars

5

• With different sources, essentially continuous coverage.• No observed power-law turbulent spectrum on scales: 1 to ~1000 AU.

Kendall’s tau test for censored data: P(no correlation) ~60%• Inhomogeneity in Galactic distribution of TSAS + v.f.f.<~1%• TSAS is not pervasive.• If TSAS is tracing the end-scales of turbulence then turbulence may dissipate

in bursts or active pockets, or it dissipates very fast.

Does the power spectrum

extend down to AU-scales?

* : interferometricother: pulsars