44. In which constellation is the Crab Nebula m 1 located?

M1-Crab Nebula

M 1 is the famous crab nebula, which is an amorphous expanding gas cloud. It is classified as a planetary nebula, but it is completely different from the typical planetary nebula in essence. It has proved to be a supernova remnant.

Basic information of M 1:

Right ascension 05: 31.5 (0531+21)

Declination (degree: meter) +2 1:0 1

Constellation: Taurus

Distance to Earth: 6,300 light years

Apparent magnitude: 8.4

About 1054 (the first year of Renzong in the Northern Song Dynasty), the unusually bright supernova event occurred at about 4 am on July 4, and there are observation records in Chinese history books. This supernova exploded brighter than Venus, about four times as bright as Venus, that is, -6 and so on. Its residue (the gas cloud ejected during the explosion) is the crab nebula now seen. "Song Yaohui" records: "From the beginning to May of the first year, I went out to the east in the morning and closed the sky. White as white during the day, awn horns everywhere, red and white in color. Every time I see the 23rd, the 1054 supernova is called "China supernova" by western astronomical circles. The discovery of Navajo Canyon and Whitemesa in Arizona and Chaco Canyon National Park in New Mexico shows that this supernova may also be recorded by Anasazi Indians. The abstract of this research can be found on the Anazasi Art Online website of Chaco Canyon. In addition, Ralph R. Robbins of the University of Texas also found that the Membres Indians in New Mexico may have described this supernova. This 1054 supernova is now named Taurus CM according to the law of variable stars. It is one of the few supernovae observed in our galaxy in history.

This nebula-like relic was discovered by john Bevis in 173 1 and marked in his Encyclopedia Britannica. 1758 On August 28th, Charles Messier, who was looking for Halley's Comet, was predicted to return for the first time and discovered it independently. At first, he thought it was a comet. Of course, he soon realized that it had no displacement at all and marked it as September 1758+02. It was the discovery of this celestial body that prompted Charles Messier to start compiling his nebula list. It was the discovery of this celestial body that gave him the idea of searching for comets with a telescope, because this celestial body is very similar to a real comet (1758 de la Nux, C/ 1758 K 1) in his small refracting telescope. 1771June 10, messier learned about Bevis's previous discovery from a letter and admitted Bevis's earliest discovery right.

173 1 year, Beavis, a British astronomy enthusiast, first discovered this hazy oval fog point with a small telescope. Messier catalog published in 177 1 listed it as 1 celestial body: M 1. In the new catalog of nebula clusters, its number is NGC 1952. 1844, which was when W.P. Ross made a large-scale reflecting telescope observation by himself. According to his visual impression, he described the nebula as a crab claw, so he named it the crab nebula, which is still in use today.

This nebula was named "Crab Nebula" because of a sketch drawn by Sir Ross around 1844. In the earliest observation, messier, Bode and William Herschel correctly described that this nebula could not be decomposed into stars, but William Herschel thought it was a cluster and could be decomposed with a larger telescope. John Herschel and Sir Ross mistakenly thought that it could "just decompose" into stars. They and others, including Lassell of 1850 s, obviously mistake the fiber structure for a recognizable star. At the end of 19, the early spectral observations of Winlock and others revealed the gas properties of this celestial body. The first photo of M 1 was taken by 1892 with a 20-inch telescope. The earliest detailed spectral analysis was completed by Vesta Slipher from 19 13 to 19 15. He found that the emission line in the spectrum is split; This was later thought to be the result of the Doppler effect, in which some nebulae are approaching us (so the spectral lines will shift blue) and others are far away from us (the spectral lines will shift red). Heber D. Curtis temporarily classified this celestial body as a planetary nebula (Curtis 19 18) according to the photos of the Lick Observatory, and 1930 denied this view. But this wrong classification still appears in many latest manuals. 192 1 year, C.O. Lampland of Lowell Observatory found that all parts of the nebula have obvious movements and changes, and the brightness is also changing, especially in several small areas near the stars in the center of the nebula (Lampland 192 1). In the same year, J.C. Duncan of Mount Wilson Observatory compared the photos taken in 1 1.5 years, and found that the crab nebula expanded at an average rate of 0.2 "per year. Tracing back to this movement, we can find that this expansion began about 900 years ago (Duncan 192 1). It was also in this year that Knut Lundemark discovered that this nebula was related to supernova 1054 (Lundemark 192 1). 1942 According to the observation of Mount Wilson Observatory 100-inch Hooke Telescope, the accurate expansion age calculated by Walter Baade? is 760 years, which means that the nebula began to expand around1180 (baade1942); Later observation revised this time to 1 140 years. The real supernova explosion occurred in 1054, which indicates that the expansion of the nebula must be accelerated. The nebula is composed of supernova explosion materials. At present, its diameter has expanded to about 10 light-year, and it is still expanding outward at an ultra-high speed of up to 1 0,800 km/s. Its emission line spectrum consists of two main parts. It was first observed by Roscoe Frank Sanford in 19 19. See (Sanford 19 19). The first type is emission line spectrum (including hydrogen emission line), and the bright fiber part from the nebula is light red. The other part is the continuous spectrum, which comes from the blue background of the nebula and is produced by highly polarized "synchrotron radiation". Synchrotron radiation is emitted by high energy (fast moving) electrons in a strong magnetic field. This explanation was first proposed by the Soviet astronomer J. shklovsky (1953) and supported by the observations of Jan H. Oort and T. Walraven (1956). Synchrotron radiation also appears in other "explosions" in the universe, such as the active core of the irregular galaxy M82 and the strange jet of the giant elliptical galaxy M87. This amazing feature of the crab nebula in the visible light band can be clearly seen from the photos taken by David Marin of the British Australian Observatory with the Paloma telescope and the photos taken by Paul Scowen on the Paloma Mountain. In 1948, the Crab Nebula proved to be a powerful radio source, named and marked Taurus A, and later called 3C 144. The X-rays emitted by the nebula were also discovered by the Aerobee sounding rocket with X-ray detector launched by the Naval Research Laboratory in April 1963. This X-ray source is named Taurus X- 1. The observation of the crab nebula on the lunar cover on July 5, 1964 by/kloc-0, and the same observation in 1974 and 1975 proved that the X-ray emitted from an area took at least 2 minutes, and the energy emitted by the crab nebula through X-rays was 65433 higher than that in the optical band. Nevertheless, even in the visible band, the luminosity of this nebula is enormous: its distance is 6,300 light years (accurately measured by Virginia trimble (1973)), so its apparent brightness corresponds to an absolute magnitude of about -3.2, which is more than 1000 times that of the sun. Its total luminosity in all bands is estimated to be 100000 times that of the sun, which is 5 * 10 38 erg/s! 19681M65438+1October 9th, a pulsed radio source, crab nebula pulsar (also known as NP 0532, "NP" refers to NRAO (National Radio Observatory) pulsar, or PSR0531+2/kloc-. The discoverer was an astronomer at the Arecibo Observatory in Puerto Rico, using a 300-meter radio telescope. This pulsar is the one to the right (southwest) of a pair of stars near the center of the nebula in the photo. This pulsar is also the first optical band pulsar to be discovered. It was W.J. Kirk, M.J. Disney and D.J. Taylor of Stewart Observatory in Tucson, Arizona at 9: 30 pm on196965438+1October 15 (according to Simon Milton's record, It was discovered at 3: 30 on1969 65438+1October 16). They found it with a 90 CM (36 inches) telescope on Kit Peak ... According to the symbol of supernovae, this optical pulsar is sometimes named Taurus cm. Now people think that this pulsar is a fast-rotating neutron star: it rotates about 30 times per second! This period is set accurately, because the "hot spots" on the surface of neutron stars will emit pulses in almost all electromagnetic wave bands. Neutron star is a kind of celestial body with high density, which is higher than the density of nucleus, and it gathers more than one solar mass within 30 kilometers. Its interaction with the magnetic field in the nebula makes the rotation slow down gradually; This is also the main energy source that makes the nebula shine; As mentioned earlier, this energy source is 100000 times stronger than our sun. In the visible light band, the apparent magnitude of this pulsar is 16, etc. The absolute magnitude of this tiny star is +4.6, which is equivalent to the luminosity of our sun in the visible light band! Jeff Hester and Paul Scowen used the Hubble Space Telescope to study the crab nebula M 1 (see Sky&; Telescope magazine 1995 1 page 40). They used the continuous research of HST to provide new evidence for studying the dynamics and evolution of the crab nebula and its pulsars. Recently, HST's astronomical team also studied the core of the crab nebula. This celestial body received so much attention that astronomers at that time were divided into two parts: one was related to the Crab Nebula and the other was not. 1In June, 969, the "Crab Nebula Seminar" was held in flug, Arizona (for the meeting results, see PASP 1970, Volume 82-burnham). 1970 The 46th IAU (International Astronomical Society) seminar held at the Bank Observatory in Jiao Derel in August was also devoted to this celestial body. Simon Milton wrote a good pamphlet about the Crab Nebula M 1 in 1978, which is still the most popular and informative (this is also the source of a lot of information here). The Crab Nebula can be easily found by Taurus zeta (or Taurus 123). This star is the "southern corner" of the bull, and it is a third-class star. It is easy to find it in the east-northeast direction of the alpha star of Taurus. M 1 is located at Zeta's north latitude 1 degree and west longitude 1 degree, which is slightly south-west half degree of another sixth-grade star, Struve 742. This kind of nebula is easy to see in the clear and dark sky, and it is also easy to be blocked by the skylight background under non-ideal conditions. M 1 can only be regarded as a black spot in the binocular of 7x50 or 10x50. At a larger magnification, it can be seen that it is an elliptical nebula-like spot surrounded by fog. In a telescope with a diameter of at least 4 inches, some details will appear, and some faint spots and stripes can be seen inside the nebula; John Mallas reports that under the best conditions, experienced observers can see them inside the nebula. Fans can confirm messier's impression that M 1 is really like a dark comet with no tail in a small instrument. Only under the best conditions, with a larger telescope with a diameter of at least 16 inch, can we see the fine fibrous structure. Because the crab nebula is only 1.5 degrees away from the ecliptic, it often encounters planets, and occasionally it is covered by planets and the moon (mentioned several times before). M 1 happens to be in the Milky Way. The zeta star in Taurus is a strange gamma variable star in Cassiopeia. It is a rapidly rotating star with a spectral type of B4 III, spewing out an expanding gas shell, and it also has a faint spectral companion. Period of revolution is about 133 days. On the right ascension, two minutes (half a degree) earlier than M 1 is Struve 742, also called ADS 4200. This is a visible binary star. Two companion stars A (7.2, etc. Spectra F8, yellow) and B (7.8, etc. , white) are 3.6 "apart, the azimuth angle is 272 degrees, and they rotate about 30 degrees around each other.

The Crab Nebula is also a source of intense infrared source, ultraviolet light, X-ray and γ-ray. Its total radiation intensity is tens of thousands of times that of the sun. The radio pulsar in this nebula was discovered in 1968, and its pulse period is 0.033097565054 19 second (33 milliseconds), which is the shortest among known pulsars. 1969 discovered that it is also an optical pulsar. At present, it is recognized that pulsars are fast-spinning neutron stars with strong magnetism, and they are collapsed compact stars formed when supernovae explode. The mass of the crab nebula pulsar is about one solar mass, and the mass of its luminous gas is also about 1.5 solar mass, so it can be seen that the nebula was a large celestial body with several times the mass of the sun before the explosion. The distance of the nebula is about 6300 light years, and the size of the nebula is about 12 light years ×7 light years.