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Turbulent AU Structures Turbulent AU Structures RevealedRevealed by H by H22O and CHO and CH33OH MasersOH Masers
V. StrelnitskiV. StrelnitskiMaria Mitchell ObservatoryMaria Mitchell Observatory
In collaboration with: In collaboration with: J. Alexander, S. Gezari, B. Holder, J. Alexander, S. Gezari, B. Holder, N. Nezhdanova, J. Moran, M. Reed, V. N. Nezhdanova, J. Moran, M. Reed, V. ShishovShishov
SINS, Socorro, May 21-24, 2006SINS, Socorro, May 21-24, 2006
HH22O and CHO and CH33OH MasersOH Masersprovide information provide information on:on: Physics of natural masingPhysics of natural masing
Spatial and kinematical Spatial and kinematical structure of the surroundings structure of the surroundings of new-born starsof new-born stars
Physics of supersonic Physics of supersonic turbulence turbulence
CH3OH Masers in OMC-1
Johnston et al. 1997
Two Competing Interpretations:
• Maser “hot spots” are the result of a lucky coincidence of radial velocities in a homogeneous turbulent medium
• The “hot spots” are physical condensations with special conditions (density, temperature, abundances, etc)
Are H2O & H2CO Masers
or Things?
The Model (Holder The Model (Holder et al.et al. 2006):2006):
Random Kolmogorov velocity field in Random Kolmogorov velocity field in a 512a 51233 grid point box grid point box
Unsaturated and saturated maser Unsaturated and saturated maser amplificationamplification
I = I = II0 0 eeττ
I = II = I00ττ
Random fractalization of the medium Random fractalization of the medium ((d d = 1)= 1)
Does Supersonic Turbulence have
a Shock-Wave Dissipation Scale?
• Relevant parameters for dissipation:
ε = U3/L
cs
• Dissipation scale:
η = cs3 /ε = L / M3
• H2O Masers: L ~ 104 A.U.; M ~ 20 → η ~ 1 A.U.
Dimensional Approach
Physical Approach
uL= M cs
vs ~ cs
tl ~ l / ul
ts ~ l/cs
ul = uL (l / L)1/3
ts > tl as long as l > L/M3
η ~ L/M3
L
Conclusions• H2O masers are “things” and they may be ideal
probes of supersonic turbulence
• They point to: - High degree of intermittency of turbulence- Lack of energy dissipation at large scales
• They may be intimately connected with the shock-
wave dissipation scale of turbulence
• More computer simulations are needed to investigate the dependence of energy dissipation on scale for supersonic turbulence
pl = (η/l)3-d
Typical Model (Sobolev Typical Model (Sobolev et alet al. . 1998)1998)
Random Kolmogorov velocity field in a NRandom Kolmogorov velocity field in a N33 grid point grid point boxbox
Unsaturated (exponential) maser amplificationUnsaturated (exponential) maser amplificationI = I = II0 0 eeττ
Synthetic spectra and maps to be compared with Synthetic spectra and maps to be compared with observationsobservations
Result: Result: CHCH33OH hot spots may be an optical effectOH hot spots may be an optical effect
Unsaturated Amplification(Analytical Solution)
• Mean Intensity
<I> = C exp[<τ> + 0.5 <(Δτ)2>]
• The most probable realizations are within
<τ> ± [<(Δτ)2>]1/2
• If <(Δτ)2> >> 1, only a few bright spots
• Δτ τ
H2O:
T = T0 eτ ~ 1015 K τ ≈ 35
T0 ~ 1K
H2CO: τ ≈ 10
Required Maser Gains
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