Eta Aquilae

A visual band light curve for Eta Aquilae.

A visual band light curve for Eta Aquilae.

Eta Aquilae is the eighth brightest star in the constellation Aquila and one of the sky's most prominent Cepheid variables; its variability was discovered in 1784 by Edward Pigott. Eta Aql lies 8° south of Altair and near one of Aquila the Eagle's talons. Eta also represents the head of the now-defunct constellation Antinous, who was honored in the sky by the Roman emperor Hadrian and depicted as being carried by Aquila.


Eta, like other Type I Cepheids is a luminous yellow-white supergiant. It changes brightness by 0.8 magnitude and back again with precise period of 7 days 4 hours 14 minutes 22 seconds. As it dims, it dips to spectral class G and from a maximum temperature of 6,200 K to 5,300 K.


visual magnitude 3.6 to 4.4
absolute magnitude -3.91
spectral type (at max.) F6Ib
surface temperature (max.) 6,200 K
luminosity 3,100 Lsun
radius 60 Rsun
mass 7 Msun
distance 1,170 light-years
position RA 19h 52m 28.4s,
Dec +1° 0' 20"