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Nova Remnant
A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae. Over their short lifetimes, nova shells show expansion velocities of around 1000 km/s, whose faint nebulosities are usually illuminated by their progenitor stars via light echos as observed with the spherical shell of Nova Persei 1901 or the energies remaining in the expanding bubbles like T Pyxidis. Form Most novae require a close binary system, with a white dwarf and a main sequence, sub-giant, or red giant star, or the merging of two red dwarfs, so probably all nova remnants must be associated with binaries. This theoretically means these nebula shapes might be affected by their central progenitor stars and the amount of matter ejected by novae. The shapes of these nova nebulae are of much interest to modern astrophysicists. Nova remnants when compared to supernova remnants or planetary nebulae generate muc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DQ Herculis
DQ Herculis, or Nova Herculis 1934, was a slow, bright nova occurring in the northern constellation of Hercules in December 1934. This cataclysmic variable star was discovered on 13 December 1934 by J. P. M. Prentice from Stowmarket, Suffolk. It reached peak brightness on 22 December 1934 with an apparent magnitude of 1.5. The nova remained visible to the naked eye for several months. This is a binary star system consisting of a white dwarf primary with an estimated 60% of the mass of the Sun and a red dwarf secondary with 40% of the Sun's mass. They orbit each other tightly with a period of . The system shows orbital period variation, possibly due to the presence of a third body. The orbital plane of the pair is inclined by an angle of 86.5° to the line of sight from the Earth, causing the white dwarf to undergo a deep eclipse every orbit. DQ Herculis is the prototype for a category of cataclysmic variable stars called intermediate polars. The red dwarf has filled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova Remnant
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar material it sweeps up and shocks along the way. There are two common routes to a supernova: either a massive star may run out of fuel, ceasing to generate fusion energy in its core, and collapsing inward under the force of its own gravity to form a neutron star or a black hole; or a white dwarf star may accrete material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion. In either case, the resulting supernova explosion expels much or all of the stellar material with velocities as much as 10% the speed of light (or approximately 30,000 km/s). These speeds are highly supersonic, so a strong shock wave forms ahead of the ejecta. That heats the upstream plasma up to temperatures well above mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Nebula
A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to planets. The term originates from the planet-like round shape of these nebulae observed by astronomers through early telescopes. The first usage may have occurred during the 1780s with the English astronomer William Herschel who described these nebulae as resembling planets; however, as early as January 1779, the French astronomer Antoine Darquier de Pellepoix described in his observations of the Ring Nebula, "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Though the modern interpretation is different, the old term is still used. All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V1500 Cygni
__NOTOC__ V1500 Cygni or Nova Cygni 1975 was a bright nova occurring in 1975 in the constellation Cygnus. It had the second highest intrinsic brightness of any nova of the 20th century, exceeded only by CP Puppis in 1942. V1500 Cygni was discovered shining at an apparent brightness of magnitude 3.0 by Minoru Honda of Kurashiki, Japan on 29 August 1975. It had brightened to magnitude 1.7 on the next day, and then rapidly faded. It remained visible to the naked eye for about a week, and 680 days after reaching maximum the star had dimmed by 12.5 magnitudes. It is an AM Herculis type star, consisting of a red dwarf secondary depositing a stream of material onto a highly magnetized white dwarf primary. The distance of the V1500 Cygni was calculated in 1977 by the McDonald Observatory at 1.95 kiloparsecs (6,360 light years). Additionally, V1500 Cyg was the first asynchronous polar to be discovered. This distinction refers to the fact that the white dwarf's spin period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HR Delphini
HR Delphini, also known as Nova Delphini 1967, was a nova which appeared in the constellation Delphinus in 1967. It was discovered by George Alcock at 22:35 UT on 8 July 1967, after searching the sky for over 800 hours with binoculars. At the time of discovery it had an apparent magnitude of 5.0. It reached a peak brightness of magnitude 3.5 on 13 December 1967, making it easily visible to the naked eye around that time. Pre-outburst photographs taken with the Samuel Oschin telescope showed it as a ~12th magnitude star which might have been variable. HR Delphini was discovered 158 days before it reached peak brightness, and its light curve around the peak was very well observed. It had a very slow rise to maximum brightness, when compared to other classical novae. It took 230 days for HR Delphini to fade from its peak by 3 magnitudes, which makes it a "slow" nova. Its decline from peak brightness showed several brief outbursts, leading to its light curve being class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V1974 Cygni
V1974 Cygni or Nova Cygni 1992 was a nova, visible to the naked eye, in the constellation Cygnus (constellation), Cygnus. It was discovered visually with 10×50 binoculars on February 19, 1992, by Peter Collins (astronomer), Peter Collins, an amateur astronomer living in Boulder, Colorado. At that time he first noticed it, it had an apparent magnitude of 7.2. Nine hours later he saw it again, and it had brightened by a full magnitude. For this discovery Collins was awarded the AAVSO Nova Award in 1993. The nova reached magnitude 4.4 at 22:00 UT on 22 February 1992. Images from the Palomar Sky Survey taken before the nova event showed identified a possible precursor which had photographic magnitudes of 18 (blue light) and 17 (red light), but the identification of the precursor is not firm. V1974 Cygni declined from peak brightness by three magnitudes in 43 days, making it a "fast" nova. Its light curve is classified as type P (Plateau), and it may be a Nova#Recurrent_ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V476 Cygni
V476 Cygni or Nova Cygni 1920 was a nova which occurred in the constellation Cygnus in 1920. It was discovered by William Frederick Denning, an English amateur astronomer, at 09:30 GMT on 20 August 1920, at which time it had a magnitude of 3.7. It reached a peak brightness of magnitude 1.7 on 23 August 1920. Its quiescent brightness is magnitude 17.09. V476 Cygni's light curve is quite unusual, showing a rapid decline from maximum brightness, followed by a slow nearly linear fading. It is classified as a very fast nova, with a very long tail. The light curve shows a "dust dip", a fast decline to a local brightness minimum, then a small increase in brightness, and finally a long, slow decline. This dust dip is believed to is believed to coincide with the formation of dust in the material ejected from the nova as it moves away from the star and cools. All novae consist of a close binary star pair, with a white dwarf star and a "donor" star orbiting each other. The star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FH Serpentis
FH Serpentis (Nova Serpentis 1970) was a nova, which appeared in the constellation Serpens in 1970. It reached magnitude 4.4. It was discovered on February 13, 1970 by Minoru Honda located at Kurashiki, Japan. Other astronomers later studied this nova, and calculated its distances based on the decay time of its light curves. Nova Serpentis was also observed by the NASA space observatory OAO-2 Stargazer, active from 1968 to 1973. The nova was important for science because it was one of the first to be observed in multiple wavelength bands including, infrared, visible, ultra-violet, and radio. One of the observations that stood out was that it became brightest in the infrared 100 days after it was first discovered. A small emission nebula (shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RR Pictoris
RR Pictoris, also known as Nova Pictoris 1925, is a cataclysmic variable star system that flared up as a nova that lit up in the constellation Pictor in 1925. It was discovered by South African amateur astronomer R. Watson who lived in Beaufort West. At 05:50 AM on 25 May 1925, Mr. Watson was walking to work and noticed a star that he did not recognize in line with the stars α Crucis and β Carinae. He consulted his copy of Norton's Star Atlas, and realized that the unfamiliar star was a nova. Fortuitously, Mr. Watson was employed as a telegraph operator, and he promptly sent a telegram describing his discovery to the Royal Observatory at Cape Town. This quick reporting of the event allowed southern observatories to obtain spectra of the nova before it had reached maximum brightness. At the time of its discovery, RR Pictoris had an apparent magnitude of 2.3. It continued to brighten to magnitude 1.2, which it reached on 9 June 1925. It dimmed to magnitude 4 by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nova
A nova (plural novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", which is Latin for "new") that slowly fades over weeks or months. Causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. All observed novae involve white dwarfs in close binary systems. 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. 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 atmosphe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Nebulae
A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to planets. The term originates from the planet-like round shape of these nebulae observed by astronomers through early telescopes. The first usage may have occurred during the 1780s with the English astronomer William Herschel who described these nebulae as resembling planets; however, as early as January 1779, the French astronomer Antoine Darquier de Pellepoix described in his observations of the Ring Nebula, "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". Though the modern interpretation is different, the old term is still used. All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary neb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
