Aquila, The Eagle, is another ancient
constellation whose history is linked to the Greek gods. The most
often-told story is that of Hebe, daughter of Zeus and Hera, who
Before her marriage Hebe was the goddess of youth and she appeared in
ceremonies as the official cup bearer. (That's to say, in all religious
functions, she was responsible for pouring the wine.) She gave up the
post after her marriage (although some accounts say that in one ceremony
she indelicately exposed herself and was promptly sacked). In any case,
the position was open and Zeus sought a suitable replacement. Ganymede,
a splendid Trojan prince, was Zeus's eventual choice.
Zeus either disguised himself as an eagle or sent his Royal Eagle. Ganymede
was plucked from his native land and taken to Mount Olympus where he became
the wine-pourer for all the gods.
This explains why Ganymede is Jupiter's brightest and largest companion:
Jupiter of course being the Roman name for Zeus.
The constellation Aquila is supposed to represent the eagle carrying away
the youth. There are four or five fairly bright stars just below the
asterism which are meant to represent the boy (this asterism is called
"Antinous" but is not recognised any longer).
Eventually Zeus put Ganymede's own image in the skies, as the god's water
Aquila's Bayer stars are generally third and
fourth magnitude, except Altair (alpha Aql), the twelfth brightest star.
Altair spins very rapidly, completing one revolution every 6.5 hours,
which deforms the star. It is thought Altair's equatorial diameter is
twice its polar diameter.
Beta Aquilae is relatively fixed, with a faint red dwarf companion:
3.7, 11.6; PA 5º, separation 13".
Zeta Aquilae also has a very faint dwarf companion, of uncertain
period: 3.0, 12; PA 53º, separation 6.5".
Pi Aquilae: 6, 7; PA 111º, separation 1.4".
Chi Aquilae is a close binary with the separation slowly
decreasing: 5.6, 6.8; PA 77º, separation 0.5".
Eta Aquilae is a cepheid variable: 3.48-4.39 with a period of
7.18 days (more precisely 7 days, 4 hours, 14 minutes and 21.8 seconds).
The magnitude changes very gradually throughout this time period, and is
easily noticed with binoculars (using beta Aquilae, 3.7, as a reference).
Sigma Aquilae is an eclipsing binary (EB type), fluctuating between 5.14 and 5.34 every 1.95 days. The combined mass is equal to twelve suns although their densities are each only about one tenth of the sun's.
R Aquilae is a long period variable: 5.5 to 12 every 284.2 days.
The 2000 maximum should occur on 4 June.
Deep Sky Objects:
NGC 6709 is a loose cluster comprised of about forty stars. It's
approximately 2500 light years away and is located five degrees SW of zeta Aquilae.
For a closer appreciation of Aquila, visit the Binocular Section.