ALMA Detection of Masers and Dasars in the Hydrogen Recombination Lines of the Planetary Nebula Mz3

Artikel i vetenskaplig tidskrift, 2024

The hydrogen recombination lines H30 alpha, H40 alpha, H42 alpha, H50 beta, and H57 gamma and the underlying bremsstrahlung continuum emission were detected with ALMA in the bipolar nebula Mz3. The source was not spatially resolved, but the velocity profile of the H30 alpha line shows clear indication of maser amplification, confirming previous reports of laser amplification in the far-infrared H recombination lines observed with Herschel Space Observatory. Comparison between the flux densities of the H50 beta, H40 alpha, and H42 alpha lines show overcooling, or darkness amplification by stimulated absorption (dasar effect) at the LSR velocity of about -25 km s-1, which constrains the density of the absorbing region to about 103 cm-3. The H30 alpha line, on the other hand, presents maser lines at LSR velocities of -69 and -98 km s-1, which indicates ionized gas with densities close to 107 cm-3. Although the source of emission was not resolved, it was possible to find the central position of the images for each velocity interval, which resulted in a well defined position-velocity distribution.