智利阿塔卡马巨型毫米波阵列如何揭示行星诞生之谜
Perched at 5,000 metres on the Chajnantor plateau in the Chilean Andes, the Atacama Large Millimeter/submillimeter Array (ALMA) represents one of the most ambitious collaborations in astronomy. Operated by a consortium of 66 high-precision antennas that function as a single, vast interferometer, the observatory observes the universe at wavelengths between infrared and radio. Its location—the driest non-polar desert on Earth—provides an atmospheric transparency that is virtually unmatched, allowing faint millimetre-wave signals from cold cosmic dust and gas to reach the detectors with minimal absorption by water vapour.
ALMA's most transformative contribution has been to the study of protoplanetary disks: the swirling reservoirs of material around young stars from which planets eventually coalesce. Before ALMA, these disks appeared in telescopic images as featureless blurs. Its unprecedented angular resolution, equivalent to distinguishing a football at 15 kilometres, resolved them into intricate rings, gaps, and spiral arms. These structures, astronomers now understand, are signposts of planetary formation in action—gaps cleared by newborn planets sweeping up debris, and bright rings where dust accumulates under gravitational and magnetic influences.
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