3 Cassiopeiae
Encyclopedia
3 Cassiopeiae is a hypothetical star
catalogued by English astronomer John Flamsteed
. It bears no identity with actual stars observed today. Unlike 34 Tauri, which was the planet Uranus
, 3 Cas was not reconciled by later knowledge.
, the brightest radio source in the constellation, is within ten minutes of arc of Flamsteed's position for 3 Cas. Study of Cas. A has shown it to be approximately 300 years old, meaning that Flamsteed may have observed the supernova. Dimmed by intervening dust and gas (the plane of the Milky Way runs through Cassiopeia), the supernova would have appeared at about magnitude six, tying in nicely with Flamsteed's observation of 3 Cas.
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
catalogued by English astronomer John Flamsteed
John Flamsteed
Sir John Flamsteed FRS was an English astronomer and the first Astronomer Royal. He catalogued over 3000 stars.- Life :Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed...
. It bears no identity with actual stars observed today. Unlike 34 Tauri, which was the planet Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
, 3 Cas was not reconciled by later knowledge.
Identity as Cassiopeia A Supernova
3 Cas. was initially thought to be erroneous and indeed in 1875, Baily's catalogue derived from Flamsteed's utterly omits 3 Cas. This was the prevalent opinion until radioastronomy. Cassiopeia ACassiopeia A
Cassiopeia A is a supernova remnant in the constellation Cassiopeia and the brightest astronomical radio source in the sky, with a flux density of 2720 Jy at 1 GHz. The supernova occurred approximately away in the Milky Way. The expanding cloud of material left over from the supernova is now...
, the brightest radio source in the constellation, is within ten minutes of arc of Flamsteed's position for 3 Cas. Study of Cas. A has shown it to be approximately 300 years old, meaning that Flamsteed may have observed the supernova. Dimmed by intervening dust and gas (the plane of the Milky Way runs through Cassiopeia), the supernova would have appeared at about magnitude six, tying in nicely with Flamsteed's observation of 3 Cas.