Unlike other constellations, Vulpecula was not named from a character or creature from mythology that some early astronomer thought the grouping of stars resembled. When Johannes Hevelius named the constellation in 1687, he chose the name ‘Vulpecula et Anser’ or ‘fox with goose,’ as he believed that the shape looked like a fox bringing a goose to Cerberus, the “hound of Hades” that guarded the gates of the underworld. The constellation Cerberus has since become obsolete, while Hevelius’ other cluster of stars, the fox and the goose, has been renamed Vulpecula (the fox). As a homage to its original title, the brightest of the stars in the constellation is called Anser, as a nod to the now forgotten goose.
Vulpecula is a northern constellation that can be seen by observers situated between +90° and -55° of latitude. It is the night sky’s 55th largest constellation, and is located at the centre of the Summer Triangle, and therefore close to the constellations of Aquila, Lyra and Cygnus. Vulpecula is best seen in September when the Summer Triangle is prominent in the sky, and you should start your search about partway between the stars Vega in Lyra and Altair in Aquila. It is best to use a telescope or binoculars with a minimum magnification of 7×50 to spot this faint constellation.
Hercules Constellation Family
Vulpecula is a member of the Hercules family of constellations, together with Aquila, Ara, Centaurus, Corona Australis, Corvus, Crater, Crux, Cygnus, Hercules, Hydra, Lupus, Lyra, Ophiuchus, Sagitta, Scutum, Sextans, Serpens and Triangulum Australe.
– Anser (Alpha Vulpeculae), the brightest star in Vulpecula, has a visual magnitude of 4.44, and is an M0III red giant located 297 light years away from the Sun. Also known as Lucida Anseris or Lukida, the star is actually part of a binary system together with the orange spectral type K0III star 8 Vulpeculae, which is 484 light years from Earth and shines with a magnitude of 5.81.
– 23 Vulpeculae, the second brightest star in the constellation, is an orange giant (K3III) found 328 light years from our solar system that shines with a visual magnitude of 4.52. It is around 20 times bigger than our sun, and is part of a triple star system together with the stars Ab and B.
– 13 Vulpeculae, the third brightest star in Vulpecula, is a blue giant (B9.5III) located 335 light years away with a visual magnitude of 4.57. It is around 4 times bigger than our sun.
– 31 Vulpeculae, the constellation’s fourth brightest star, is a yellow giant (G7III) located 216.57 light years distant of magnitude 4.59. It has around 9 times the radius of the Sun, and is actually a variable star.
– PSR B1919+21 was discovered by Jocelyn Bell Burnell and Antony Hewish in 1967, marking the official first discovery of a pulsar. Hewish would go on to receive the Nobel Prize for Physics for the feat, with the pulsar receiving its unusual name by combining the numbers of its declination and right ascension with the word pulsar. When first discovered, PSR B1919+21 was thought to be the first signs ever received of an alien civilization; however, Thomas Gold and Fred Hoyle were able to determine that the signals being emitted by the star were actually just the strong magnetic fields of the rotating neutron stars. The pulsar is situated 2283.12 light years away from the Sun, and has a period of 1.3373 seconds, and a pulse width of 0.04 seconds.
Other stars of interest in Vulpecula includes the binary star HD 189733; the white giant 15 Vulpeculae; the blue subgiant 1 Vulpeculae; and a millisecond pulsar called PSR B1937+21.
Notable Deep Sky Objects
The constellation of Vulpecula contains a number of notable deep-sky objects, including one Messier object called the Dumbbell Nebula (M27).
– Brocchi’s Cluster is a star cluster that is known by a number of different names, including Collinder 399, and Al Sufi’s Cluster, after the Persian astronomer Al Sufi who in 964 AD wrote about it in his “Book of Fixed Stars.” Without knowing of Sufi’s discovery, Giovanni Batista Hodierna found the cluster in the 17th century, while the name Broochi is owed to the amateur astronomer who in the 1920s first mapped the star cluster. Collinder 399 references the Swedish scientist Per Collinder who listed the cluster as one of 471 open clusters in his catalog of 1931. In any case, Brocchi’s Cluster refers to the group of stars that are located in Vulpecula, close to the border of the constellation Sagitta. Its 10 brightest stars are arranged in an asterism that is sometimes referred to as the Coathanger, and you can see this portion of Brocchi’s Cluster without the use of a telescope or binoculars.
Other objects of interest in Vulpecula includes the emission nebula NGC 6820; the open clusters NGC 6823 and NGC 6885; and the biggest known galactic superstructure in the universe called the Hercules–Corona Borealis Great Wall, which contains billions of individual galaxies.