Guest star (astronomy)

In Chinese astronomy, a guest star (Chinese: 客星; pinyin: kèxīng; literally: 'guest star') is a star which has suddenly appeared in a 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 stars: novae and supernovae. The term "guest star" is used in the context of ancient records, since the exact classification of an astronomical event in question is based on interpretations of old records, including inference, rather than on direct observations.

In ancient Chinese astronomy, guest stars were one of the three types of highly transient objects (bright heavenly bodies); the other two (彗星, huixing, “broom star”, a comet with a tail; and xing bo, “fuzzy star”, a comet without a tail) being comets in modern understanding.[1] 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.[1] These contain one of the clearest early descriptions consistent with a supernova, posited to be left over by object SN 185, thus identified as a supernova remnant of the exact year 185 CE.[2] Chronicles of the contemporary Ancient Europeans are more vague when consulted for supernovae candidates.[3] Whether due to weather or other reasons for lack of observation, astronomers have questioned why the notable remnant attributed to Chinese observations of a guest star in 1054 AD (see SN 1054), is missing from the European records.[3]

See also

References

  1. ^ a b Zhentao Xu, David W. Pankenier (2000) "East-Asian Archaeoastronomy: Historical Records of Astronomical Observations of China, Japan, and Korea", ISBN 90-5699-302-X, Chapter 6, "Guest Stars"
  2. ^ Zhao FY; Strom RG; Jiang SY (2006). "The Guest Star of AD185 Must Have Been a Supernova". Chinese J Astron Astrophys. 6 (5): 635–40. Bibcode:2006ChJAA...6..635Z. doi:10.1088/1009-9271/6/5/17.
  3. ^ a b Murdin, Paul; Murdin, Lesley (1985). Supernovae. ISBN 0-521-30038-X.
Guest

Guest or The Guest may refer to:

A person who is given hospitality

Guest (surname), people with the surname Guest

"The Guest" (short story), a 1957 short story by Albert Camus

Guest (album), 1994 album by Critters Buggin

The Guest (album), a 2002 album by Phantom Planet

USS Guest (DD-472), a U.S. Navy Fletcher-class destroyer 1942–1946

Guest appearance, guest actor, guest star, etc.

Guest comic, issue of a comic strip that is created by a different person (or people) than usual

Guest host (or guest presenter), a host, usually of a talk show, that substitutes for the regular host

Guest operating system, an operating system installed on a virtual machine

Guest ranch (or dude ranch), a type of ranch oriented towards visitors or tourism

Guest statute, a statute in tort law

Guest worker, a person who works in a country other than the one of which he or she is a citizen

The Guest (TV series), a 2018 South Korean television series

The Guest (film), a 2014 American thriller film

List of novae in 2018

The following is a list of all novae that are known to have occurred in 2018. A nova is an energetic astronomical event caused by a white dwarf accreting matter from a star it is orbiting (typically a red giant, whose outer layers are more weakly attached than smaller, denser stars) Alternatively, novae can rarely be caused by a pair of stars merging with each other, however such events are vastly less common than novae caused by white dwarves.

In 2018, 15 novae were discovered in the Milky Way, 14 being classical novae, and 1 being a dwarf nova of a previously known variable star, V392 Persei, which was discovered in 1972. An additional 23 novae were discovered in the Andromeda Galaxy, 8 in Messier 81, 1 in the Triangulum Galaxy, and 1 in Messier 83.

List of novae in 2019

The following is a list of all novae that are known to have occurred in 2019. A nova is an energetic astronomical event caused by a white dwarf accreting matter from a star it is orbiting (typically a red giant, whose outer layers are more weakly attached than smaller, denser stars) Alternatively, novae can be caused by a pair of stars merging with each other, however such events are vastly less common than novae caused by white dwarfs.

In 2019, seven novae have been discovered so far, six of which were dwarf nova eruptions, one of the variable system V386 Serpentis, one from the known nova-like system 2E 1516.6-6827, and four from previously unidentified white dwarf binaries. One of these binaries, TCP J18200437-1033071, may have possibly been involved in another outburst in 1951.

Nova

A nova (plural novae or novas) or classical nova (CN, plural CNe, or Q) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star, that slowly fades over several weeks or many months.

Causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. All observed novae involve a white dwarf in a close binary system. The main sub-classes of novae are classical novae, recurrent novae (RNe), and dwarf novae. They are all considered to be cataclysmic variable stars.

Classical nova eruptions are the most common type of nova. They are likely created in a close binary star system consisting of a white dwarf and either a main sequence, subgiant, or red giant star. When the orbital period falls in the range of several days to one day, the white dwarf is close enough to its companion star to start drawing accreted matter onto the surface of the white dwarf, which creates a dense but shallow atmosphere. This atmosphere is mostly hydrogen and is thermally heated by the hot white dwarf, which eventually reaches a critical temperature causing rapid runaway ignition by fusion.

From the dramatic and sudden energies created, the now hydrogen-burnt atmosphere is then dramatically expelled into interstellar space, and its brightened envelope is seen as the visible light created from the nova event, and previously was mistaken as a "new" star. A few novae produce short-lived nova remnants, lasting for perhaps several centuries. Recurrent nova processes are the same as the classical nova, except that the fusion ignition may be repetitive because the companion star can again feed the dense atmosphere of the white dwarf.

Novae most often occur in the sky along the path of the Milky Way, especially near the observed galactic centre in Sagittarius; however, they can appear anywhere in the sky. They occur far more frequently than galactic supernovae, averaging about ten per year. Most are found telescopically, perhaps only one every year to eighteen months reaching naked-eye visibility. Novae reaching first or second magnitude occur only several times per century. The last bright nova was V1369 Centauri reaching 3.3 magnitude on 14 December 2013.

SN 1181

First observed between August 4 and August 6, 1181, Chinese and Japanese astronomers recorded the supernova now known as SN 1181 in eight separate texts.

One of only eight supernovae in the Milky Way observable with the naked eye in recorded history, it appeared in the constellation Cassiopeia and was visible in the night sky for about 185 days.

The radio and X-ray pulsar J0205+6449 (also known as 3C 58), which rotates about 15 times per second, is possibly the remnant from this event. If the supernova and pulsar are associated, the star is still rotating about as quickly as it did when it first formed. This is in contrast to the Crab pulsar, known to be the remnant of the SN 1054 supernova in the year 1054, which has lost two-thirds of its rotational energy in essentially the same time span. Recent radio surveys of 3C 58, however, indicate that this supernova remnant may be much older and thus not associated with SN 1181.

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