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We report detection of moderate to high-mass star formation in an infrareddark cloud (G11.11-0.12) where we discovered class II methanol and water maseremissions at 6.7 GHz and 22.2 GHz, respectively. We also observed the object inammonia inversion transitions. Strong emission from the (3,3) line indicates ahot (~60 K) compact component associated with the maser emission. The linewidth of the hot component (4 km/s), as well as the methanol maser detection,are indicative of high mass star formation. To further constrain the physicalparameters of the source, we derived the spectral energy distribution (SED) ofthe dust continuum by analysing data from the 2MASS survey, HIRAS, MSX, theSpitzer Space Telescope, and interferometric 3mm observations. The SED wasmodelled in a radiative transfer program: a) the stellar luminosity equals 1200L_sun corresponding to a ZAMS star of 8 M_sun; b) the bulk of the envelope hasa temperature of 19 K; c) the mass of the remnant protostellar cloud in an area8x10^17 cm or 15 arcsec across amounts to 500M_sun, if assuming standard dustof the diffuse medium, and to about 60 M_sun, should the grains be fluffy andhave ice mantles; d) the corresponding visual extinction towards the star is afew hundred magnitudes. The near IR data can be explained by scattering fromtenuous material above a hypothetical disk. The class II methanol maser linesare spread out in velocity over 11 km/s. To explain the kinematics of themasing spots, we propose that they are located in a Kepler disk at a distanceof about 250 AU. The dust temperatures there are around 150 K, high enough toevaporate methanol--containing ice mantles.Comment: 10 pages, 6 figures, Accepted for publication in Astronomy &  Astrophysics Journa

High mass star formation in the infrared dark cloud G11.11-0.12