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I came across a website saying that classical T Tauris have an "EW(Hα) > 5 angstroms".
Does anybody know what "EW" means?
"EW" stands for Equivalent Width. The equivalent width of a spectral line is essentially the range of continuum one would integrate over to get the same flux as the spectral line.
In your case, this is the Hα line.
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