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We report the Chandra detection of hard X-ray emission from the Welch ring inW49A, an organized structure of ultra-compact (UC) HII regions containing adozen nascent early-type stars. Two UC HII regions are associated with hardX-ray emission in a deep Advanced CCD Imaging Spectrometer image exposed for96.7 ks. One of the two X-ray sources has no near-infrared counterpart and isextended by ~5 arcsec, or ~0.3 pc, at a distance of ~11.4 kpc, which isspatially aligned with the cometary radio continuum emission associated withthe UC HII region. The X-ray spectrum of the emission, when fit with a thermalmodel, indicates a heavily absorbed plasma with extinction of\~5x10^{23}/cm^{2}, temperature of ~7 keV, and X-ray luminosity in the 3.0-8.0keV band of ~3x10^{33} ergs/s. Both the luminosity and the size of the emissionresemble the extended hard emission found in UC HII regions in Sagittarius B2,yet they are smaller by an order of magnitude than the emission found inmassive star clusters such as NGC 3603. Three possibilities are discussed forthe cause of the hard extended emission in the Welch ring: an ensemble ofunresolved point sources, shocked interacting winds of the young O stars, and awind-blown bubble interacting with ambient cold matter.

Hard X‐Rays from Ultracompact HiiRegions in W49A