Sh2-216, the largest PN of the sky (Stephane ZOLL)

Sh2-216, the largest PN of the sky

Link: http://www.astrosurf.com/zoll/images/images_PN.html

Sh2-216, the largest PN of the sky

Link: http://www.astrosurf.com/zoll/images/images_PN.html

SH2-216 (aka GN 04.41.3, Simeis 288, Marsalkova 44, LBN 742, YM 22, GN 04.41.3), in Perseus, is the largest known PN, one of the closest (425 light years) and one of the oldest. Its apparent diameter is reported to be 1.6° but here is measured at more than 2° (for comparison, the Moon diameter is 0.5°).

This PN is very diffuse with a brighter east border, probably due to the interaction with the interstellar medium.

The signal in the Ha/NII channel is more important, but the diffuse OIII signal remains sufficient to allow visual observation with big Dobsons (~16").

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SH2-216 ( = GN 04.41.3, Simeis 288, Marsalkova 44, LBN 742, YM 22), dans la constellation de Persée, est la plus grande nébuleuse planétaire connue, une des plus anciennes et a priori la 2eme plus proche (425AL). Son diamètre apparent est donné à 1.6° (mais sur l'image ci-dessous, elle est mesurée à environ 105x120'), à comparer aux 0.5° de la Lune.

Elle est très diffuse, avec une bordure est plus marquée, probablement en raison de son déplacement et interaction dans le milieu stellaire environnant.

La réponse dans la raie Ha/NII est la plus importante où l'on peut distinguer des irrégularités de structure, et la réponse dans la raie OIII est plus uniforme, mais néanmoins significative, ce qui la rend observable dans les très grands Dobson (~400mm).

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Sh2-216, the largest PN of the sky

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