give away

先程と同じニュースからです。

give awayにも様々な定義がございますが本文では「・・・の正体をあかす」（『リーダーズ英和　第２版』研究社）の意になり、Merriam-Webster's Online Dictionary, 11th Editionでは’disclose, reveal’と載っていました。(Shou-VR*)

Kepler-78b Is Just Like Earth - But A Bit Hotter
Because the planet orbits so close to its star, it was also possible to measure gravitational effects that gave away its mass.

http://uk.news.yahoo.com/kepler-78b-just-earth-bit-hotter-022539497.html?vp=1#tdQtbT9