Eta Geminorum

Eta Geminorum (η Gem / η Geminorum) is a triple star system in the constellation Gemini. It also has the traditional names Tejat Prior, Propus and Praepes.

Eta Geminorum A is a spectroscopic binary. The primary is a semiregular variable star of type SRA whose brightness changes with a period of 234 days between magnitude +3.15 and +3.9. It is located 350 light years from the Sun and is a red giant of the spectral type M3. The secondary, probably a class B, orbits with a period of 8.2 years. Eta Geminorum B, a class G dwarf, orbits the pair with a period of at least 700 years. [ [http://adsabs.harvard.edu/abs/1944ApJ...100...63M The Spectrographic Orbit and Light-Variations of η Geminorum] , Dean B. McLaughlin and Suzanne E. A. van Dijke, "Astrophysical Journal" 100 (July 1944), pp. 63–68.] ^, [ [http://www.astro.uiuc.edu/~kaler/sow/propus.html Eta Geminorum] at Jim Kaler's STARS.]

Eta Geminorum is near the ecliptic, so it can be occulted by the Moon and very rarely by planets. The last occultation by a planet took place on July 27 1910 by Venus, and the next to last on July 11 1837 by Mercury.

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