| Emission nebula | |
|---|---|
| Planetary nebula | |
 NGC 4361 imaged with a 24-inch telescope | |
| Observation data: J2000 epoch | |
| Right ascension | 12h 24m 30.8s [1] |
| Declination | −18° 47′ 5.6″ [1] |
| Distance | 3,377.2±153.6 [1] ly |
| Apparent magnitude (V) | 10.9 [2] |
| Apparent dimensions (V) | 1.3' x 1.3' [2] |
| Constellation | Corvus [3] |
| Designations | NGC 4361, PN G294.1+43.6 |
NGC 4361 is a planetary nebula in the constellation of Corvus. [3] [1] [2] It is included in the Astronomical League's Herschel 400 Observing Program.
NGC 4361's central star is an extremely hot [WC] Wolf-Rayet type star. Its temperature is 126,000 K. [4] It is nearly 18,000 times brighter than the Sun, but is only 6.1% its size. This star left the asymptotic giant branch between 5776 and 8018 years ago. [4]
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 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 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 small, hot star. Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius and become visible as a planetary nebula. The nebula 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 1514 is a planetary nebula in the zodiac constellation of Taurus, positioned to the north of the star Psi Tauri along the constellation border with Perseus. Distance to the nebula is 466 pc, according to GAIA DR2 data.
NGC 6302 is a bipolar planetary nebula in the constellation Scorpius. The structure in the nebula is among the most complex ever observed in planetary nebulae. The spectrum of NGC 6302 shows that its central star is one of the hottest stars known, with a surface temperature in excess of 250,000 degrees Celsius, implying that the star from which it formed must have been very large.
NGC 6781 is a planetary nebula located in the equatorial constellation of Aquila, about 2.5° east-northeast of the 5th magnitude star 19 Aquilae. It was discovered July 30, 1788 by the Anglo-German astronomer William Herschel. The nebula lies at a distance of 1,500 ly from the Sun. It has a visual magnitude of 11.4 and spans an angular size of 1.9 × 1.8 arcminutes.
NGC 5307 is a planetary nebula in the southern constellation of Centaurus, positioned less than 3° to the northeast of the star Epsilon Centauri. It was discovered by English astronomer John Herschel on April 15, 1836. The nebula is located at a distance of approximately 10.6 kilolight-years from the Sun. The central star, designated PNG 312.3+10.5, is a weak emission-line star, superficially similar to the WC subtype of Wolf–Rayet stars. It has a spectral class of O(H)3.5 V.
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 6578 is a planetary nebula located in Sagittarius. It is magnitude 13.5 with diameter 8 arc seconds. It has a 16th magnitude central star, which is an O-type star with a spectral type of Of. It is seen near the star 16 Sagittarii.
NGC 7662 is a planetary nebula located in the northern constellation Andromeda. It is known as the Blue Snowball Nebula, Snowball Nebula, and Caldwell 22. This nebula was discovered October 6, 1784 by the German-born English astronomer William Herschel. In the New General Catalogue it is described as a "magnificent planetary or annular nebula, very bright, pretty small in angular size, round, blue, variable nucleus". The object has an apparent visual magnitude of 8.3 and spans an angular size of 32″ × 28″. Parallax measurements give a distance estimate of 5,730 ± 340 ly (1,757 ± 103 pc).
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 5315 is a planetary nebula in the southern constellation Circinus. Of apparent magnitude 9.8 around a central star of magnitude 14.2, it is located 5.2 degrees west-southwest of Alpha Circini. It is only visible as a disc at magnifications over 200-fold. The nebula was discovered by astronomer Ralph Copeland in 1883. The central star has a stellar class of WC4 and is hydrogen deficient with an effective temperature of 76-79 kK. The distance to this nebula is not known accurately, but is estimated to be around 6.5 kilolight-years.
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.
Little Ghost Nebula, also known as NGC 6369, is a planetary nebula in the constellation Ophiuchus. It was discovered by William Herschel.
NGC 6572 is a planetary nebula with magnitude 8.1, easily bright enough to make it an appealing target for amateur astronomers with telescopes. NGC 6572 is a young planetary nebula. NGC 6572 began to shed its gases a few thousand years ago. Because of this, the material is still quite concentrated, which explains its abnormal brightness. The envelope of gas is currently racing out into space at a speed of around 15 kilometres per second. As it becomes more diffuse, it will dim. It is located within the large constellation of Ophiuchus and at low magnification, it will appear to be just a colored star, but higher magnification will reveal its shape. NGC 6572 was discovered in 1825 by the German astronomer Friedrich Georg Wilhelm von Struve. According to several sources such as Sky & Telescope, this object received the nicknames Blue Racquetball, Emerald Nebula, Green Nebula, Turquoise Orb.
NGC 7026 is a planetary nebula located 6000 light-years away, in the constellation of Cygnus. The central star of the planetary nebula has a spectral type of [WO3], indicating a spectrum similar to that of an oxygen-rich Wolf–Rayet star. An analysis of Gaia data suggests that it is a binary system.
NGC 1501 is a complex planetary nebula located in the constellation of Camelopardalis, it was discovered on 27 August 1787 by William Herschel. It is also known as the Oyster Nebula.
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 6778 is a planetary nebula (PN) located about 10,300 light years away from the Sun in the equatorial constellation of Aquila. It is positioned 5° to the SSW of the prominent star Delta Aquilae. This nebula was discovered by German astronomer Albert Marth during the period 1863–1865. English astronomer John Herschel may have mistakenly catalogued it as NGC 6785, as nothing can be found now at the coordinates he gave for it. In the New General Catalogue it was described as a "small, elongated, ill-defined disc".
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