Guest star (astronomy)
Encyclopedia
In Chinese astronomy
, the term guest star (ke xing 客星) refers to a star
which has suddenly appeared visible in the place where no star had previously been observed and becomes invisible again after some time. The term is a literal translation from ancient Chinese astronomical records. Modern astronomy recognizes that guest stars are manifestations of cataclysmic variable star
s: nova
e and supernova
e. Still, the term "guest star" is still used in the context of ancient records, since the exact classification of an astronomical event in question is based on interpretations of old records, rather than on direct observations. In ancient Chinese astronomy guest stars were one of the three types of "new stars", the other two being comet
s in modern understanding. The earliest Chinese record of guest stars is contained in Han Shu (漢書), the history of Han Dynasty
(206 BCE
— 220 CE
), and all subsequent dynastic histories had such records.
Of ancient European chronicles the possible early indications at supernovae are vague references to astronomical events which may be interpreted as the supernova of 185
recorded by Chinese. At the same time astronomers are in dispute why a notable supernova of 1054
is missing from European records.
Chinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, the term guest star (ke xing 客星) refers to a star
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...
which has suddenly appeared visible in the place where no star had previously been observed and becomes invisible again after some time. The term is a literal translation from ancient Chinese astronomical records. Modern astronomy recognizes that guest stars are manifestations of cataclysmic variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
s: nova
Nova
A nova is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner...
e and supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
e. Still, the term "guest star" is still used in the context of ancient records, since the exact classification of an astronomical event in question is based on interpretations of old records, rather than on direct observations. In ancient Chinese astronomy guest stars were one of the three types of "new stars", the other two being comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s in modern understanding. The earliest Chinese record of guest stars is contained in Han Shu (漢書), the history of Han Dynasty
Han Dynasty
The Han Dynasty was the second imperial dynasty of China, preceded by the Qin Dynasty and succeeded by the Three Kingdoms . It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han. It was briefly interrupted by the Xin Dynasty of the former regent Wang Mang...
(206 BCE
Common Era
Common Era ,abbreviated as CE, is an alternative designation for the calendar era originally introduced by Dionysius Exiguus in the 6th century, traditionally identified with Anno Domini .Dates before the year 1 CE are indicated by the usage of BCE, short for Before the Common Era Common Era...
— 220 CE
Common Era
Common Era ,abbreviated as CE, is an alternative designation for the calendar era originally introduced by Dionysius Exiguus in the 6th century, traditionally identified with Anno Domini .Dates before the year 1 CE are indicated by the usage of BCE, short for Before the Common Era Common Era...
), and all subsequent dynastic histories had such records.
Of ancient European chronicles the possible early indications at supernovae are vague references to astronomical events which may be interpreted as the supernova of 185
SN 185
SN 185 was a supernova which appeared in the year 185 AD, near the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA Dec , in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han, and may have been recorded in Roman...
recorded by Chinese. At the same time astronomers are in dispute why a notable supernova of 1054
SN 1054
SN 1054 is a supernova that was first observed as a new "star" in the sky on July 4, 1054 AD, hence its name, and that lasted for a period of around two years. The event was recorded in multiple Chinese and Japanese documents and in one document from the Arab world...
is missing from European records.