the peculiar emission line star mwc349 hosts the only known hydrogen recombination line maser known to date. we propose to investigate this unique maser whose line flux is found to increase steeply up to the shortest wavelength accessible from the ground, at iso wave- lengths.the principal questions addressed are: (i) what is the form of growth of maser line flux with wavelength, and (ii) at what wavelength does the maser finally cut off. we expect the saturated growth which characterizes the submm maser transitions to terminate somewhere in the range 300 to 30 microns either due to the maser running out of gain or to atomic processes which quench the level inversion. measurements of the form of the cutoff and of the source continuum will help to decide between these mechanisms. the form of growth of the maser line flux gives information on the length of the gain path as a function of wavelength. these data help to decide between possible locations of the maser on the disk, either upper and lower surface, or its inner edge. interpretation of maser velocities will then be possible in terms of disk kinematics and the mass of the system. in this way, the study of the maser with iso will help to clarify the nature of the disc around this enigmatic source which is most consistently interpreted as a very massive zams star which has dispersed its parental cloud, but which is still surrounded by its accretion disk.
Instrument
LWS01 , LWS04 , SWS01 , SWS07
Temporal Coverage
1996-05-16T13:27:25Z/1997-05-09T18:20:21Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
