NGC7538-IRS1 N: modelling a maser disc

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NGC7538-IRS1 Nmodelling a maser disc
Michele Pestalozzi, M. Elitzur, J. Conway, R.
Booth
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Discs in high-mass star-forming regions

• Zhang et al. 1998
• Cesaroni et al. 2000
• Shepherd et al. 2001
• Sandell et al. 2003

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NGC7538-IRS1N the disc
6.7 GHz
Pestalozzi et al. 2004
Minier et al. 1998
Gaume et al. 1995
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The data
disp. / LOS Vel.
Pestalozzi et al. 2001
Minier et al. 1998
R.A. / DEC
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Comparison 6.7 / 12.2 GHz
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Assumptions

• Keplerian rotating disc seen edge-on
• Gain per unit length between R0 and Ri
  power-law (1 / rp)
• Amplification of a continuum background
• (Tb 104 K)
• 4. Maser is unsaturated

Geometry
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Model
(3.)
(1.)
(2.,4.)
Free parameters h, W
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Results
30 M8 (from others) 1000 AU in radius h 0.39
6.7 GHz
12.2 GHz
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The kink
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Important note
IRAM 041911522
PdB, CS
Belloche et al.2002
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MASER vs Thermal emission
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Summary

• Found and modelled a disc in NGC7538
• 30 M8, 1000 AU radius, h0.39
• Masers behave as thermal emission regarding
  optical depth
• Optimal tool to study small linear and dynamical
  scales at large distances
• Future 3D modelling, outliers, satellite
  lines...

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Thank you