The constellation Phoenix takes its name from the mythological firebird, but it is not an ancient constellation. It is one of 12 Southern Hemisphere constellations first described in Johann Bayer's 1603 book "Uranometria." Phoenix has 13 stars: four are orange giants, three are white dwarfs, three are binary systems, two are yellow giants and one is a white giant.
The modern system of naming stars comes from "Uranometria." The Bayer designation labels each star in a constellation, from brightest to dimmest, with the corresponding letter of the Greek alphabet, followed by the Latin genitive case of the constellation. The brightest star in Phoenix is alpha Phoenicis, and the dimmest is nu Phoenicis. Size, energy and distance from Earth determine a star's brightness.
Orange and Yellow Giants
The stars alpha, gamma, delta and epsilon Phoenicis are orange giants. Delta and mu Phoenicis are yellow giants. Orange and yellow giants are hotter burning versions of red giants. Orange and yellow giants are low-mass stars at a late stage in their evolutionary cycle. As a smaller star runs out of hydrogen fuel in its core, it expands up to 100 times its size into a red or orange giant. In approximately 5 billion years, the sun will become a red giant.
Iota, kappa and nu Phoenicis are white dwarfs. A white dwarf is the phase of stellar evolution a red giant enters into as it loses energy. Its nuclear fuel exhausted, the red giant sheds its outer mass, leaving only the white, hot-burning core. A typical white dwarf is just a little larger than Earth, though it is half as massive as the sun.
Beta, zeta and lambda Phoenicis are binary star systems. Astronomer William Herschel coined the term "binary star" in the 1790s when he discovered pairs of stars traveling together. Binary stars orbit one another, and often appear as one star to the naked eye. By measuring each star's effect on the other, astronomers can gather a great deal of information about a star's mass, composition and gravitational pull.
Eta Phoenicis is a white giant. Unlike red giants, white giants are not dying stars late in their evolutionary phase. White giants are massive, hot-burning, main sequence stars up to 10 times larger than the sun. White giants burn hydrogen quickly, end their lives in supernova and leave behind a neutron star or a black hole.