| Emission nebula | |
|---|---|
| Planetary nebula | |
 NGC 7139 | |
| Observation data: J2000 epoch | |
| Right ascension | 21h 46m 08.586s [1] |
| Declination | +63° 47′ 29.45″ [1] |
| Apparent magnitude (V) | 13 [2] |
| Constellation | Cepheus [2] |
NGC 7139 is a planetary nebula located in the constellation of Cepheus. It was discovered on November 5, 1787, by astronomer William Herschel. [2]
NGC 2346 is a planetary nebula near the celestial equator in the constellation of Monoceros, less than a degree to the ESE of Delta Monocerotis. It is informally known as the Butterfly Nebula. The nebula is bright and conspicuous with a visual magnitude of 9.6, and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape.
The Eskimo Nebula, also known as the Clown-faced Nebula, Lion Nebula, or Caldwell 39, is a bipolar double-shell planetary nebula (PN). It was discovered by astronomer William Herschel in 1787. The formation resembles a person's head surrounded by a parka hood. It is surrounded by gas that composed the outer layers of a Sun-like star. The visible inner filaments are ejected by a strong wind of particles from the central star. The outer disk contains unusual, light-year-long filaments.
NGC 5189 is a planetary nebula in the constellation Musca. It was discovered by James Dunlop on 1 July 1826, who catalogued it as Δ252. For many years, well into the 1960s, it was thought to be a bright emission nebula. It was Karl Gordon Henize in 1967 who first described NGC 5189 as quasi-planetary based on its spectral emissions.
NGC 2438 is a planetary nebula in the southern constellation of Puppis. Parallax measurements by Gaia put the central star at a distance of roughly 1,370 light years. It was discovered by William Herschel on March 19, 1786. NGC 2438 appears to lie within the cluster M46, but it is most likely unrelated since it does not share the cluster's radial velocity. The case is yet another example of a superposed pair, joining the famed case of NGC 2818.
NGC 7027, also known as the Jewel Bug Nebula, is a very young and dense planetary nebula located around 3,000 light-years from Earth in the constellation Cygnus. Discovered in 1878 by Édouard Stephan using the 800 mm (31 in) reflector at Marseille Observatory, it is one of the smallest planetary nebulae and by far the most extensively studied.
NGC 40 is a planetary nebula discovered by William Herschel on November 25, 1788, and is composed of hot gas around a dying star. The star has ejected its outer layer which has left behind a smaller, hot star with a temperature on the surface of about 50,000 degrees Celsius. Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius, and is about one light-year across. About 30,000 years from now, scientists theorize that NGC 40 will fade away, leaving only a white dwarf star approximately the size of Earth.
NGC 246 is a planetary nebula in the constellation Cetus. It is the first known planetary nebula to have a hierarchical triple star system at its center. The nebula and the stars associated with it are listed in several catalogs, as summarized by the SIMBAD database. NGC 246 was discovered by William Herschel in 1785.
NGC 6210 is a planetary nebula located in the constellation Hercules, approximately 5.4 ± 1.3 kly from the Sun. It is positioned about 38° above the galactic plane at a vertical distance of about 3.3 kilolight-years (1 kpc) and thus has little extinction from intervening interstellar dust. This object was first recorded as a star-like feature by Joseph Lalande on March 22, 1799. However, credit for the discovery of a nebula goes to Wilhelm Struve in 1825. John L. E. Dreyer described it as, "a planetary nebula, very bright, very small, round, disc and border".
NGC 7354 is a planetary nebula located in the northern circumpolar constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".
NGC 2867 is an elliptical Type II planetary nebula in the southern constellation of Carina, just over a degree to the NNW of the star Iota Carinae. It was discovered by John Herschel on April 1, 1834. Herschel initially thought he might have found a new planet, but on the following night he checked again and discovered it had not moved. The nebula is located at a distance of 7,270 light-years from the Sun.
NGC 6884 is a planetary nebula located in the constellation Cygnus, less than a degree to the southwest of the star Ο1 Cygni. It lies at a distance of approximately 12.5 kly from the Sun. The nebula was discovered on May 8, 1883 by American astronomer Edward C. Pickering.
NGC 3242 is a planetary nebula located in the constellation Hydra.
NGC 6072 is a planetary nebulae in the southern constellation of Scorpius. It has a dynamical age of 104 years. Its circumstellar envelope is likely to be rich in carbon as it has very strong CN (cyanide) spectral lines. CN spectral lines are generally not detected in oxygen rich AGB (asymptotic giant branch) circumstellar envelopes. NGC 6072 also shows H2 (hydrogen) emission and intense CO (carbon monoxide) emission which has been mapped displaying bipolarity and some gas at high velocity. The evolution of this planetary nebulae is likely to be dominated by photodissociation and ion/radical molecular reactions. Shock chemistry is also likely to be important.
NGC 1360, also known as the Robin's Egg Nebula, is a planetary nebula in the constellation of Fornax. It was identified as a planetary nebula due to its strong radiation in the OIII (oxygen) bands. Reddish matter, believed to have been ejected from the original star before its final collapse, is visible in images. It is slightly fainter than IC 2003.
NGC 1535 is a planetary nebula in the constellation of Eridanus, discovered by William Herschel on February 1, 1785. It is very similar to the Eskimo Nebula in both color and structure but the central star can be quite difficult to observe visually.
NGC 7048 is a planetary nebula in the constellation of Cygnus. The bright star to the lower left of the nebula is a magnitude 10.5 star, designated TYC 3589-4652-1. The nebula is slightly brighter along the west and east sides. This planetary nebula has an apparent magnitude of 12.1. NGC 7048 was discovered by Édouard Stephan on 19 October 1878 using a 31.5-inch reflector.
NGC 2242 is a planetary nebula in the constellation Auriga. It was discovered by Lewis A. Swift on November 24, 1886, and was thought to be a galaxy until a study published in 1987 showed it to be a planetary nebula. The nebula is located about 6,500 light-years away, and about 1,600 light-years above the galactic plane.
NGC 6886 is a planetary nebula in the constellation Sagitta. It was discovered by Ralph Copeland on September 17, 1884. It is 4.6 ± 1.0 kiloparsec (15.0 ± 3.3 kly) distant from Earth, and is composed of a hot central post-AGB star that has 55% of the Sun's mass yet 2700 ± 850 its luminosity, with a surface temperature of 142,000 K. The planetary nebula is thought to have been expanding for between 1280 and 1600 years.
NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range between 1.7 and 2.6 kpc.
NGC 6445, also known as the Little Gem Nebula or Box Nebula, is a planetary nebula in the constellation Sagittarius. It was discovered by William Herschel on May 28, 1786. The distance of NGC 6445 is estimated to be slightly more than 1,000 parsecs based on the parallax measured by Gaia, which was measured at 0.9740±0.3151 mas.
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