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PZ Telescopii
PZ Telescopii, also known as HD 174429 or simply PZ Tel, is a young star in the constellation Telescopium. It has a maximum magnitude of 8.342 (too faint to be seen with the unaided eye), varying by 0.0342 of a magnitude over roughly 23 hours. It has been classified as a BY Draconis variable, and is one of the closest and hence brightest pre-main-sequence stars to Earth.〔
Based upon an annual parallax shift of 19.42±0.98 milliarcseconds as measured by the Hipparcos satellite, this system is from Earth, with a margin of error of .〔
PZ Telescopii has an effective surface temperature of around 5338 K (the Sun has an approximate surface temperature of 5778 K), a mass around 1.13 times, and diameter 1.23 times that of our Sun.〔 It has a debris disk calculated to span from a radius of 35 to 165 astronomical units (AU), as well as a substellar companion with 36 times the mass of Jupiter orbiting at a distance of 16 AU, discovered in 2008. The companion, currently known as PZ Tel B, is thought to be a brown dwarf; however it is possible (though very unlikely) that it is an extremely large Jupiter-like planet, in which case it would be PZ Tel b, and the first such planet to be directly imaged.〔
PZ Telescopii was originally considered to be a member of the Beta Pictoris moving group; however in a 2012 paper, James Jenkins of Universidad de Chile and colleagues used three methods to calculate its age and came up with a figure of around 24 million years—significantly older than the 12 million years of the association.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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