<p>"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.</p>

<p>In your case, this is the Hα line.</p>

CC BY-SA 3.0
2016-04-20T08:59:06.363Z
+1, but for future readers, the formula would be nice :)
pela
CC BY-SA 4.0
2021-05-03T16:48:07.207Z
I agree with you, @pela. It would be nice to have a formula to back it up.
Questioner
CC BY-SA 3.0
2016-04-20T01:55:53.610Z
2016-04-20T01:55:53.610Z
smashbro
<p>I came across a website saying that classical T Tauris have an "EW(Hα) > 5 angstroms".</p>

<p>Does anybody know what "EW" means?</p>

<p>Thanks.</p>

<astrophysics><star-formation>
What does "EW(Hα)" mean?
Jason Yang
# What does "EW(Hα)" mean?

(Asked by: username_0 on 2016-04-20)

I came across a website saying that classical T Tauris have an "EW(Hα) > 5 angstroms".

Does anybody know what "EW" means?

Thanks.

**Tags:** astrophysics, star-formation

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## 1 answers

### Answer by username_1 on 2016-04-20. Score: 7 | Accepted answer

"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.

> **Comments:**
> **username_2**: +1, but for future readers, the formula would be nice :)  
> **username_3**: I agree with you, @pela. It would be nice to have a formula to back it up.  

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