行星状星云

[ noun ]
a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star
<noun.object>

Planetary \Plan"et*a*ry\, a. [Cf. L. planetarius an astrologer,
F. plan['e]taire planetary. See {Planet}.]
1. Of or pertaining to the planets; as, planetary
inhabitants; planetary motions; planetary year.

2. Consisting of planets; as, a planetary system.

3. (Astrol.) Under the dominion or influence of a planet.
``Skilled in the planetary hours.'' --Drayton.

4. Caused by planets. ``A planetary plague.'' --Shak.

5. Having the nature of a planet; erratic; revolving;
wandering. ``Erratical and planetary life.'' --Fuller.

{Planetary days}, the days of the week as shared among the
planets known to the ancients, each having its day.
--Hutton.

{Planetary nebula}, a nebula exhibiting a uniform disk, like
that of a planet.