Serpens is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda.
A planetary nebula, is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
Perseus is a constellation in the northern sky, being named after the Greek mythological hero Perseus. It is one of the 48 ancient constellations listed by the 2nd-century astronomer Ptolemy, and among the 88 modern constellations defined by the International Astronomical Union (IAU). It is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, and Triangulum to the west. Some star atlases during the early 19th century also depicted Perseus holding the disembodied head of Medusa, whose asterism was named together as Perseus et Caput Medusae; however, this never came into popular usage.
Messier 107 or M107, also known as NGC 6171, is a very loose globular cluster in a very mildly northern part of the sky in Ophiuchus, and is the last such object in the Messier Catalogue.
George Howard Herbig was an American astronomer at the University of Hawaii Institute for Astronomy. He is perhaps best known for the discovery of Herbig–Haro objects.
Messier 46 or M46, also known as NGC 2437, is an open cluster of stars in the slightly southern constellation of Puppis. It was discovered by Charles Messier in 1771. Dreyer described it as "very bright, very rich, very large." It is about 5,000 light-years away. There are an estimated 500 stars in the cluster with a combined mass of 453 M☉, and it is thought to be a mid-range estimate of 251.2 million years old.
The Owl Nebula is a starburst ("planetary") nebula approximately 2,030 light years away in the northern constellation Ursa Major. The estimated age of the Owl Nebula is about 8,000 years. It is approximately circular in cross-section with faint internal structure. It was formed from the outflow of material from the stellar wind of the central star as it evolved along the asymptotic giant branch. The nebula is arranged in three concentric shells/envelopes, with the outermost shell being about 20–30% larger than the inner shell. A mildly owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.
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 1275 is a type 1.5 Seyfert galaxy located around 237 million light-years away in the direction of the constellation Perseus. NGC 1275 corresponds to the radio galaxy Perseus A and is situated near the center of the large Perseus Cluster of galaxies.
Omicron Persei is a triple star system in the constellation of Perseus. From parallax measurements taken during the Hipparcos mission it is approximately 1,100 light-years from the Sun.
NGC 602 is a young, bright open cluster of stars located in the Small Magellanic Cloud (SMC), a satellite galaxy to the Milky Way. It is embedded in a nebula known as N90.
NGC 5398 is a barred spiral galaxy in the southern constellation of Centaurus. It was discovered June 3, 1836 by John Herschel. Distance estimates range from 5.39 Mpc to 18.30 Mpc. The tip of the red-giant branch method yields a distance of 11.6 Mpc, while the Tully–Fisher relation shows values of around 8.5 Mpc. It is receding with a heliocentric radial velocity of 1,219 km/s.
IC 5146 is a reflection/emission nebula and Caldwell object in the constellation Cygnus. The NGC description refers to IC 5146 as a cluster of 9.5 mag stars involved in a bright and dark nebula. The cluster is also known as Collinder 470. It shines at magnitude +10.0/+9.3/+7.2. Its celestial coordinates are RA 21h 53.5m, dec +47° 16′. It is located near the naked-eye star Pi Cygni, the open cluster NGC 7209 in Lacerta, and the bright open cluster M39. The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago; the nebula is about 12 arcmins across, which is equivalent to a span of 15 light years.
NGC 1893 is an open cluster in the constellation Auriga. It is about 12,400 light years away. The star cluster is embedded in the HII region IC 410.
IC 348 is a star-forming region in the constellation Perseus located about 315 parsecs from the Sun. It consists of nebulosity and an associated 2-million-year-old cluster of roughly 400 stars within an angular diameter of 20″. The most massive stars in the cluster are the binary star system BD+31°643, which has a combined spectral class of B5. Based upon infrared observations using the Spitzer Space Telescope, about half of the stars in the cluster have a circumstellar disk, of which 60% are thick or primordial disks.
NGC 6604 is a young open cluster of stars in the equatorial constellation of Serpens, positioned about 1.5° north of the Eagle Nebula. The cluster was discovered by William Herschel on July 15, 1784. It is located at a distance of 4,580 light years from the Sun, about 210 ly (65 pc) above the galactic plane. NGC 6604 forms the densest part of the Ser OB2 association of co-moving stars.
Kepler-25 is a star in the northern constellation of Lyra. It is slightly larger and more massive than the sun with a luminosity 21⁄2 times that of the sun. With an apparent visual magnitude of 10.6, this star is too faint to be seen with the naked eye.
RCW 36 is an emission nebula containing an open cluster in the constellation Vela. This H II region is part of a larger-scale star-forming complex known as the Vela Molecular Ridge (VMR), a collection of molecular clouds in the Milky Way that contain multiple sites of ongoing star-formation activity. The VMR is made up of several distinct clouds, and RCW 36 is embedded in the VMR Cloud C.
NGC 672 is a spiral galaxy in the northern constellation of Triangulum, positioned around 2° to the southwest of the star Alpha Trianguli. The original object designated NGC 672 was discovered by the German-born astronomer William Herschel on 26 October 1786, but this was later cataloged as NGC 614. The object now identified as NGC 672 was discovered by John Herschel on 11 November 1827.
HM Sagittae is an intensively-studied D-type symbiotic nova in the northern constellation of Sagitta. It was discovered by O. D. Dokuchaeva and colleagues in 1975 when it increased in brightness by six magnitudes. The object displays an emission line spectrum similar to a planetary nebula and by 1977 is detected in the radio band. Unlike a classical nova, the optical brightness of this system did not rapidly decrease with time, although it showed some variation. It displays activity in every band of the electromagnetic spectrum from X-ray to radio.
