IRAS 04553-6825: first extra-galactic SiO maser

These photos show the location of the very large (`monster') star, IRAS 04553-6825, in the Large Magellanic Cloud (LMC), a satellite galaxy to our Milky Way, some 160,000 light-years away. The first extragalactic silicon-oxide (SiO) maser has just been discovered in the atmosphere of this star by means of a new, very sensitive receiver at the SEST submillimetre telescope at the ESO La Silla Observatory.

The upper photo is reproduced from a CCD frame that was obtained in January 1996 with the 3.5-metre New Technology Telescope (NTT) and the EMMI Multi-mode instrument. It is a 20-min H-alpha exposure which shows the large, interstellar clouds in this region of the LMC. IRAS 04553-6825 is situated at the centre of the square box, at the edge of the cloud, from which it was formed by contraction at an earlier epoch. The box measures approx. 1 x 1 arcmin and the full frame about 7 x 7 arcmin. North is up and east is left.

The extremely red colour of this star is demonstrated on the four frames below. They show the field delimited by the box on exposures in four different spectral regions; from left to right: B (blue, 4000-5000 A), V (green-yellow, 5000 - 6000 A), R (red, 6000 - 7000 A) and I (infrared, 7000 - 9000 A). While the star is hardly visible in the blue, it is the brightest object on the infrared exposure. These CCD-frames were obtained in October 1995 with the 0.9-m Dutch telescope at La Silla. The exposure times were 10 min (B), 5 min (V), 2 min (R) and 1 min (I), respectively.