![]() Pa 30 is the supernova remnant of SN 1181. Here the nebula is seen as long thin filaments radiating out from the central star. | |
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Date | between August 4 and August 6, 1181 |
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Constellation | Cassiopeia |
Right ascension | 00h 53m 11.2s |
Declination | +67° 30′ 02.4″ |
Epoch | J2000 |
Remnant | Pa 30 |
Host | Milky Way |
Notable features | Visible at night for 185 days |
Peak apparent magnitude | 0? |
Preceded by | SN 1054 |
Followed by | SN 1572 |
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 five supernovae in the Milky Way confidently identified in pre-telescopic records, [1] it appeared in the constellation Cassiopeia and was visible and motionless against the fixed stars for 185 days. F. R. Stephenson first recognized that the 1181 AD "guest star" must be a supernova, because such a bright transient that lasts for 185 days and does not move in the sky can only be a galactic supernova. [2]
Pa 30 was discovered in 2013 by American amateur astronomer Dana Patchick while searching for planetary nebula in WISE infrared data. [4] It was the 30th nebula discovered by his searches, and as a result it is designated Pa 30. Pa 30 appeared as a nearly-round nebula roughly 171x156 arc-seconds in size, with an extremely blue central star. Pa 30 refers to both the nebula (originally catalogued as IRAS 00500+6713) and the central star (designated as WD J005311). The shell is bright in the infrared, but very faint in the optical, at first visible only by light in the [O III] band.
In 2019, optical spectroscopy of the central star revealed a very hot star with an intense stellar wind expanding at a very high velocity of 16,000 km/s and a composition mainly of carbon, oxygen, and neon (with no hydrogen or helium). [5] Such a speed could only arise from a supernova or an event of similar magnitude, more specifically from a merger of two white dwarfs. X-ray spectroscopy studies of the shell also revealed a very hot nebula containing carbon-burning ashes which can only be produced in a supernova. [6] However, the remnant star of Pa 30 is a white dwarf, not one of the conventional supernova remnants (neutron stars or black holes). It has been suggested that Pa 30 is the remnant of a rare class of supernovae known as "sub-luminous Type Iax Supernova" and that a merger of a CO white dwarf and an ONe white dwarf produced the remnant shell along with its supermassive white dwarf remnant. More recent observations in the [SII] band also revealed fine filamentary structures within the shell that had not previously been seen. [7] [8]
A 2021 study measured the expansion velocity of ~1,100 km/s for the nebula from optical spectroscopy of the [S II] doublet. Together with the angular size of Pa 30 and the GAIA distance of 2.3 kpc, the age of the nebula could be estimated to be approximately 1,000 years. This made Pa 30 the new prime candidate for the remnant of the SN 1181 event. [9] Furthermore, the expansion velocity of the nebula and the inferred absolute brightness of the 1181 event are consistent with a Type Iax Supernova, making Pa 30 the only SN Iax remnant in our Galaxy and the only one which can be studied in detail.
With a temperature near 200,000 K, [5] WD J005311 is among the hottest stars known. [10] The extreme properties of the central star are being powered by the residual radioactive decay of 56Ni, where the usual half-life of 6.0 days from electron capture is increased to many centuries due to the nickel being completely ionized. [11]
Before 2013, the only plausible conventional supernova remnant in the old historical area for the supernova was the supernova remnant 3C 58. This remnant has a radio and X-ray pulsar that rotates about 15 times per second. So historically, SN 1181 had been associated with 3C 58 and its pulsar, although many researchers noted that this association is problematic. For example, if the supernova and pulsar are associated, then the star is still rotating about as quickly as it did when it first formed. [12] 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 span of time. [13]
The age of the 3C 58 remnant has been estimated by many measures. [14] [15] Most directly, the proper motion of the expanding shell of 3C 58 has been measured three times, resulting in a distance-independent estimated age of around 3500 years. The measures of the decline rate of the radio flux have substantial variability and uncertainty, so they are not useful for estimating the remnant's age. Age estimates involving the remnant's energy and the swept-up mass are both not useful due to large uncertainties with the distance as well as the presumed energetics and densities. The pulsar is offset from the center of 3C 58, implying an age of ~3700 years, although it is possible to be substantially younger if its transverse velocity happens to be high. The pulsar spin-down age is 5380 years. The neutron star cooling age is >5000 years. With these age estimates, 3C 58 is much too old a remnant to be associated with SN 1181.
The possible sky position of the 1181 supernova has been revised to include additional information on the proximity of the "guest star" to adjacent Chinese constellations, resulting in a greatly smaller error region. [16] This improved region does not contain 3C 58, because the guest star does not have proximity to two constellations as reported. So SN 1181 is not associated with 3C 58. Rather, this new small region contains Pa 30, which is independently known to be a ~800 year old supernova remnant.
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately 51.4 kiloparsecs from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos from the explosion reached Earth on February 23, 1987 and was designated "SN 1987A" as the first supernova discovered that year. Its brightness peaked in May of that year, with an apparent magnitude of about 3.
SN 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a Type Ia supernova that occurred in the Milky Way, in the constellation Ophiuchus. Appearing in 1604, it is the most recent supernova in the Milky Way galaxy to have been unquestionably observed by the naked eye, occurring no farther than 6 kiloparsecs from Earth. Before the adoption of the current naming system for supernovae, it was named for Johannes Kepler, the German astronomer who described it in De Stella Nova.
Timeline of neutron stars, pulsars, supernovae, and white dwarfs
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus. The common name comes from a drawing that somewhat resembled a crab with arms produced by William Parsons, 3rd Earl of Rosse, in 1842 or 1843 using a 36-inch (91 cm) telescope. The nebula was discovered by English astronomer John Bevis in 1731. It corresponds with a bright supernova recorded by Chinese astronomers in 1054 as a guest star. The nebula was the first astronomical object identified that corresponds with a historically-observed supernova explosion.
A pulsar wind nebula, sometimes called a plerion, is a type of nebula sometimes found inside the shell of a supernova remnant (SNR), powered by winds generated by a central pulsar. These nebulae were proposed as a class in 1976 as enhancements at radio wavelengths inside supernova remnants. They have since been found to be infrared, optical, millimetre, X-ray and gamma ray sources.
3C 58 or 3C58 is a pulsar and supernova remnant within the Milky Way. The object is listed as No. 58 in the Third Cambridge Catalogue of Radio Sources.
The Crab Pulsar is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054. Discovered in 1968, the pulsar was the first to be connected with a supernova remnant.
SN 1572, or B Cassiopeiae, was a supernova of Type Ia in the constellation Cassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 and was independently discovered by many individuals.
A Type Ia supernova is a type of supernova that occurs in binary systems in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white dwarf.
NGC 1309 is a spiral galaxy located approximately 120 million light-years away, appearing in the constellation Eridanus. It is about 75,000 light-years across, and is about 3/4s the width of the Milky Way. Its shape is classified as SA(s)bc, meaning that it has moderately wound spiral arms and no ring. Bright blue areas of star formation can be seen in the spiral arms, while the yellowish central nucleus contains older-population stars. NGC 1309 is one of over 200 members of the Eridanus Group of galaxies.
IC 443 is a galactic supernova remnant (SNR) in the constellation Gemini. On the plane of the sky, it is located near the star Eta Geminorum. Its distance is roughly 5,000 light years from Earth.
The known history of supernova observation goes back to 1006 AD. All earlier proposals for supernova observations are speculations with many alternatives.
SN 1895B was a supernova event in the irregular dwarf galaxy NGC 5253, positioned 16″ east and 23″ north of the galactic center. It is among the closest known extragalactic supernova events. The supernova was discovered by Williamina Fleming on December 12, 1895 after noticing an unusual spectrum on a photographic plate taken July 18, 1895, and was initially given the variable star designation Z Centauri. The light curve is consistent with an event that began ~15 days before the discovery plate was taken, and this indicates the supernova reached a peak visual magnitude of up to 8.49±0.03.
A type Iax supernova is a rare subtype of type Ia supernova, which leaves behind a remnant star, known as zombie star, rather than completely dispersing the white dwarf. Type Iax supernovae are similar to type Ia, but have a lower ejection velocity and lower luminosity. Type Iax supernovae may occur at a rate between 5 and 30 percent of the Ia supernova rate. Thirty supernovae have been identified in this category.
SN 386 is a probable transient astronomical event in the constellation Sagittarius, which appeared as a "guest star" that was reported by Chinese astronomers in 386 CE.
IRAS 00500+6713 is the catalogued infrared source for an unusual nebula in Cassiopeia, while the central star has a designation WD J005311, with the whole system designated as Pa 30. The central star and its surrounding shell were created by the supernova seen in the year 1181 as reported by Chinese and Japanese observers. Both the nebula and central star have unique and extreme properties, pointing to their creation by a rare type Iax supernova, where two ultra-dense white dwarfs in-spiral to a collision and explosion. The Pa 30 system was discovered in 2013 by amateur astronomer Dana Patchick, the extreme properties of the central star were first seen in 2019 by Gvaramadze and colleagues, and they recognized that the system was created in a low-luminosity supernova event from a merger of two white dwarfs.
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3C 392 is a supernova remnant located in the constellation Aquila. It was discovered by Gart Westerhout in 1958 as part of a study of continuous radiation in the Milky Way at a frequency of 1390 MHz.