At magnitude 4.44, Alpha Vulpeculae is the brightest star in the modern constellation Vulpecula, the Fox. The star has traditional names Lukida, Lucida Anseris or Anser. This name is a shortened version of the original, from the time when the constellation had the name "Vulpecula cum Ansere", meaning "the Little Fox with the Goose".
The star is set off a bit to the west of the "W" that makes the most obvious part of the faint constellation, and with the name "Anser" seems to represent the dropped part of the constellation's names.
Properties and Evolution
Anser is a class M0 III giant with a relatively cool surface temperature of 3850 K. From its rather distance of 295 light years, allowing for infrared radiation, it has a luminosity 390 times the Sun's, and a large radius of 45 times solar. This figure agrees well with the radius of 53 suns derived from a direct measure of its angular diameter.
With a mass around 1.5 suns, Anser may still be brightening, with a dead helium core that has yet to fuse to carbon. After this it will dim a bit and settle as a class K orange giant. It might also be brightening for the second time, with a dead carbon-oxygen core. A high nitrogen content, almost twice the Sun's, suggests that by-products from a hydrogen-fusing shell around the dead core are reaching the surface. On the other hand, the star's metal content is down; its iron abundance is about two-thirds solar.
Companion
The star is sometimes listed as having a companion. With binoculars, a fifth magnitude star (8 Vulpeculae, also a class K giant) is seen about 7' or 0.12° away. The apparent duplicity is only a line-of-sight coincidence, however, as 8 Vulpeculae lies 485 light years away - 60% farther than Anser.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]