Porrima (Gamma Virginis) -- Double Star System in Virgo
Porrima -- Goddess of Prophecy
The gibbous moon shown brightly in the early morning sky, washing out the galaxies in
Virgo. But I expected the bright moon, and thus focused on Jupiter and double-stars
which are unaffected by moon-light. One of my choices for the night was Porrima
(Gamma Virginis), a multiple star system, in which the two brightest members appear
in the telescope as two equally-bright stars. Porrima derives its name from the ancient
Roman goddess of prophecy.
The two F0 type stars orbit each other once every 171 years. The orbit is highly off-set
causing the degree of separation of the two stars to change drastically. Back it 2010,
the separation was less than one arcsecond and separating the two was a real
challenge. Now in 2018, the separation is 2.7 arcseconds (my estimation) and is easy
to do with the 6.1-inch refractor at high power. The colors are white with a
yellowish-cast. Since the stars are so bright that when in focused the yellow is not
obvious but becomes more apparent when one moves the stars slightly out of focus.
The goddess did not provide me with any predictions of future events, except that I
would likely return to this double star in the near future.