Open Access

This article has an erratum: [https://doi.org/10.1051/0004-6361/201425540e]


Table 4

Calculated optical thickness τc of the corona at the center of the disk (see text).

f (MHz) 150 164 236 327

year
2004 16 (4.2) 10 (5.0) 3.4 (1.7) 1.6 (0.8)
2007 1.9 (1.1) 1.5 (0.8) 0.7 (0.4) 0.3 (0.2)
2008–9 1.1 (0.5) 0.9 (0.4) 0.4 (0.2) 0.2 (0.1)
2010 1.5 (0.7) 1.2 (0.5) 0.5 (0.3) 0.3 (0.1)

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