First extra-galactic SiO maser

This is a small part of the microwave spectrum of the maser star IRAS 04553-6825 in the Large Magellanic Cloud (LMC), a satellite galaxy to the Milky Way.

The region shown is centered at a frequency of about 86 GHz (wavelength about 3 mm), where SiO molecules in the atmosphere of this very large star produce a strong emission by the maser effect.

The abscissa shows the velocity, as indicated by the Doppler shift of the SiO emission; the ordinate shows the relative intensity. The line at the centre has a measured velocity of about 275 km/sec, very near the mean velocity of the LMC. There is therefore no doubt that this star is located in the LMC.

The observation was made with a new state-of-art millimetric receiver at the 15-metre Swedish-ESO Submillimetre Telescope (SEST) at the La Silla Observatory. The signal represents 26 hours of observation.