Large impacts around a solar-analog star in the era of terrestrial planet formation

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Science  29 Aug 2014:
Vol. 345, Issue 6200, pp. 1032-1035
DOI: 10.1126/science.1255153

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A cosmic dust storm that came and went

Unseen planets may still kick up a lot of dust. While rocky exoplanets finish their growth, destructive collisions among them throw off clouds of fine debris that shine bright in the infrared. Meng et al. monitored the star ID8 with the Spitzer Space Telescope and observed a rapid thermal flareup and fadeout within only 2 years. This modulation is consistent with recent collisions among its orbiting protoplanets. Such dynamic variations in presumed planet-forming systems encourage more studies that exploit the real-time changes.

Science, this issue p. 1032


The final assembly of terrestrial planets occurs via massive collisions, which can launch copious clouds of dust that are warmed by the star and glow in the infrared. We report the real-time detection of a debris-producing impact in the terrestrial planet zone around a 35-million-year-old solar-analog star. We observed a substantial brightening of the debris disk at a wavelength of 3 to 5 micrometers, followed by a decay over a year, with quasi-periodic modulations of the disk flux. The behavior is consistent with the occurrence of a violent impact that produced vapor out of which a thick cloud of silicate spherules condensed that were then ground into dust by collisions. These results demonstrate how the time domain can become a new dimension for the study of terrestrial planet formation.

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