Query : 2008A&A...492..475L

2008A&A...492..475L - Astronomy and Astrophysics, volume 492, 475-480 (2008/12-3)

A study of the asymmetry in the H2O maser line at λ = 1.35 cm on the base of the hyperfine structure.


Abstract (from CDS):

The results of analyzing asymmetry in the H2O maser lines at λ=1.35 cm are presented. We investigated in detail the known mechanism of the asymmetry origin due to the hyperfine structure of the 616-523 transition and different (not equidistant) positions of the corresponding triplet components. The triplet of the lines is characterized by the sum of extinction factors that are continuously transformed into a single-peaked asymmetric extinction coefficient, with the increase in the Doppler widths (characterizing by effective Doppler velocity uD). A noticeable asymmetry corresponds to uD≤0.5-1km/s. For higher values of uD the extinction factor approaches a Gaussian shape with the decreasing magnitude of the profile asymmetry. An appreciable asymmetry in unsaturated maser lines can only arise at uD≤0.5km/s, if there are very narrow linewidths (Δu≃0.2-0.4km/s). But observed saturated masers possess a fairly high degree of the line asymmetry, 10-40%. Most probably, this asymmetry is a result of rebroadening of the linewidth up to the value that is comparable to the width of the asymmetric extinction coefficient.

Abstract Copyright:

Journal keyword(s): line: profiles - masers - radiative transfer

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2217 1
2 IRAS 19095+0930 cor 19 11 54.09216 +09 35 49.6896           ~ 99 0
3 NAME DR 21(OH) M Rad 20 39 01 +42 29.8           ~ 87 0
4 SH 2-128 HII 21 32 09.9 +55 52 53           ~ 167 1
5 NGC 7538S Y*O 23 13 44.8 +61 26 51           ~ 87 1

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