Issue |
Astron. Astrophys. Suppl. Ser.
Volume 141, Number 2, January II 2000
|
|
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Page(s) | 185 - 192 | |
DOI | https://doi.org/10.1051/aas:2000118 | |
Published online | 15 January 2000 |
Investigation of the H2O maser emission in G43.8-0.1
1
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No. 1, Apdo Postal 51 y 216, 72840 Tonantzintla, Puebla, Mexico
2
Sternberg Astronomical Institute, 13 Universitetskij prospekt, Moscow 119899, Russia
Send offprint request to: E.E. Lekht
Received:
8
December
1998
Accepted:
6
August
1999
Observations and analysis of the H2O maser emission source,
associated with the star-forming region G43.8-0.1, are
presented. The observations were carried out on the RT-22 radio
telescope of the Pushchino Radio Astronomy Observatory (Russia) in
1994–1998. A new flare of emission of a group of features at
radial velocities from 37.5 to 39.5 km s-1, which took place in
1996–1998, was observed. For the 38.2 km s-1 feature, a dependence
between flux density and linewidth ()
was derived; it indicates that the maser is unsaturated or partly
saturated.
The evolution of emission of the 42.2 km s-1 maser condensation is
traced at a timespan of 16 years. The flux density was plotted
versus linewidth for this feature
(in the
coordinates). This dependence
contains two branches, largely shifted with respect to each other.
The transition from one branch to the other took 2.5 years,
while the linewidth was fluctuating. Possible causes of existence
of the two branches in the maser emission evolution are discussed.
An analysis of the entire data set for 1976–1998 has shown that
the time interval between the minima of integral flux in
G43.8-0.1 was 18 ± 1 yr. This figure can be taken as the
period of the H2O maser activity in G43.8-0.1.
Key words: masers / stars: formation / radio lines: stars
© European Southern Observatory (ESO), 2000