astrosphere

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The central portion of a cell aster exclusive of the rays.
• noun The entire cell aster with the exception of the centrosome.

from The Century Dictionary.

• noun In cytology: In the karyokinetic figure, the central portion of the aster, inclusive of the region in which the centrosome lies, but exclusive of the astral rays; the attraction-sphere of Van Beneden. Fol, 1891; Strasburger, 1892. See cut at aster, 7.
• noun The whole aster, exclusive of the centrosome; the astral sphere of Mark.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A cavity filled with hot gas blown into the interstellar medium by stellar winds.