We present direct evidence for anomalous microwave emission in the Perseus molecular cloud, which shows a clear rising spectrum from 11 to 17 GHz in the data from the COSMOSOMAS experiment. By extending the frequency coverage using W ilkinson Microwave Anisotropy Probe maps convolved with the COSMOSOMAS scanning pattern, we reveal a peak flux density of 42 ± 4 Jy at 22 GHz integrated over an extended area of 1°.65 × 1°.0 centered on R.A. = 55°.4 ± 0°.1 and decl. = +31°.8 ± 0°.1 (J2000). The flux density that we measure at this frequency is nearly an order of magnitude higher than can be explained in terms of normal Galactic emission processes (synchrotron, free-free, and thermal dust). An extended IRAS dust feature, G159.6-18.5, is found near this position, and no bright unresolved source that could be an ultracompact H II region or gigahertz-peaked source could be found. An adequate fit for the spectral density distribution can be achieved from 10 to 50 GHz by including a very significant contribution from electric dipole emission from small spinning dust grains. © 2005. The American Astronomical Society. All rights reserved.
- Diffuse radiation
- Dust, extinction
- ISM: individual (G159.6-18.5)
- Radiation mechanisms: general
- Radio continuum: ISM