PZ Cassiopeiae
Template:Short description Template:Use dmy dates Template:Starbox begin Template:Starbox image Template:Starbox observe Template:Starbox character Template:Starbox astrometry Template:Starbox detail Template:Starbox catalog Template:Starbox reference Template:Starbox end PZ Cassiopeiae is a red supergiant star located in the constellation of Cassiopeia, and a semi-regular variable star.
Characteristics
PZ Cassiopeiae is a luminous red supergiant star, one of the largest stars currently known with a radius over 1,200 times the Sun's radius (Template:Solar radius), and also one of the most luminous of its type, around 240,000 times more luminous than the Sun (Template:Solar luminosity).[1] It is likely to be part of the Cas OB5 stellar association although apparently much younger than the other stars in the association.[2] The star is losing mass at around Template:Val per year and has also once been described as a hypergiant.[3][4]
Its distance from Earth was initially estimated to be around 7,800 light-years (2.4 kiloparsecs). Subsequent studies of the star using the water masers that surround it have allowed to refine both the distance and the parameters of this star, deriving an accurate parallax of Template:Val, corresponding to a distance of 9,160 light-years (2.81 kiloparsecs), that translates a luminosity for it around Template:Solar luminosity, and an initial mass of 20 to 25 times that of the Sun. These parameters are all similar to those estimated for the red hypergiant VY Canis Majoris.[2][5]
A Gaia Data Release 2 parallax of Template:Val gives the star a luminosity below Template:Solar luminosity with a corresponding radius of Template:Solar radius.[6]
In 1956, R. Weber announced his discovery that the star's brightness varies.[8] PZ Cas is a slow semi-regular variable star with the period quoted as 925 days in the General Catalogue of Variable Stars,[9] although periods of 850 and 3,195 days have been derived.[10][11] The visual range is approximate magnitude 8–10, large for this type of variable.[11]
Supergiant or AGB star
PZ Cas has traditionally been treated as a massive supergiant, comparable to others such as VY CMa, but there is some evidence that it is a possible less massive O-rich S- or SC-type Asymptotic Giant Branch (AGB) or post-AGB star. It shows enrichment of Zr and Ba, but not Li as would be expected for a true supergiant.[12]
Companion
PZ Cas has a Cepheid variable companion, a 13th magnitude star 12" away.[13]
Notes
References
- ↑ Template:Cite journal
- ↑ 2.0 2.1 Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite web
- ↑ Template:Cite journal
- ↑ Template:Cite journal
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedlesqueren - ↑ 11.0 11.1 Template:Cite journal
- ↑ Template:Cite journal
- ↑ Template:Cite journal