The Running Man Nebula is a reflection nebula embedded in the larger H II region Sharpless 279 (Sh2-279). It lies 1,500 light-years away in the constellation Orion. The nebula is part of the asterism known as Orion’s Sword, along with its brighter and larger neighbour, the Orion Nebula (M42).
The Running Man Nebula got its popular nickname because its shape resembles the figure of a running man. The nebula’s unique appearance and proximity to the larger Orion Nebula make it a popular astrophotography target. The two nebulae appear in the same field of view and are frequently photographed together.
While the Orion Nebula is visible even without binoculars, the outline of the running man in the Running Man Nebula is a difficult target for amateur telescopes. It is best seen photographically. The reflection nebula itself can be glimpsed in small and medium telescopes.
The whole Running Man Nebula is believed to be illuminated and excited by 42 Orionis, a hot young stellar object located within the nebula. 42 Orionis has the stellar classification B1V and is also catalogued as c Orionis and HD 37018.
The star has a mass 12 times that of the Sun and a surface temperature of 25,400 K. It is in fact a triple star system. The primary component has two companions. One is a close spectroscopic companion at a separation of only 0.16 arcseconds and the other is a magnitude 7.5 star separated by 1.6 arcseconds from the primary. The system shines at magnitude 4.59.
In images, 42 Orionis appears 3.8 arcminutes from the centre of Sh2-279. The nebula is home to other massive young stars, including 45 Orionis, a yellow giant or subgiant, and the variable B-type star KX Orionis.
The star-forming region Sh2-279 consists of the reflection nebulae NGC 1973, NGC 1975, and NGC 1977, and the open cluster NGC 1981. The Running Man Nebula is commonly associated with the New General Catalogue designation NGC 1977, which refers to the reflection nebulosity around the star 42 Orionis (c Orionis) in the southeastern part of Sh2-279. The designation is sometimes used for the whole nebula complex.
NGC 1977 is the brightest and largest nebula in Sh2-279. It has a radius of 7.5 light-years. It was discovered by the German-born British astronomer William Herschel in 1786. Herschel catalogued the object as “H V 30” with a note “42 Orionis and neb[ula].”
NGC 1973 and NGC 1975 were discovered by German astronomer Heinrich Louis d’Arrest, director of the Østervold Observatory at the University in Copenhagen, in 1862 and 1864.
The nebula NGC 1975 has a radius of 2 light-years, and NGC 1973 is the smallest of the three nebulae with a radius of 1 light-year. The nebulae are separated by darker lanes of dust that form the figure of the running man in the sky.
NGC 1973, NGC 1975, and NGC 1977 were included in the New General Catalogue in 1888.
The open cluster NGC 1981 (Collinder 73) was discovered by John Herschel, son of William, on January 4, 1827. The cluster has an apparent magnitude of 4.2 and stretches across 28 arcminutes.
The reflection nebulae NGC 1973, NGC 1975 and NGC 1977 are associated with the Orion Molecular Cloud Complex, a vast star-forming region that stretches across most of the constellation Orion.
The Running Man Nebula is sometimes called the Ghost Nebula because its shape resembles that of a cartoon ghost. It should not, however, be confused with the Ghost Nebula (Sh2-136), a spooky-looking nebula in the constellation Cepheus.
Observations with the Hubble Space Telescope in 2012 revealed a candidate proplyd (ionized protoplanetary disk) in the nebula NGC 1977. The proplyd had a bent protostellar jet and a possible ionization front facing 42 Orionis.
Proplyds are photoevaporating protoplanetary disks found around very young stars. Almost 180 of these objects have been detected in the Orion Nebula, the nearest region of massive star formation to the Sun.
The Running Man Nebula contains the largest number of known proplyds outside the Orion Nebula. Seven of these objects have been confirmed so far. Six were discovered with the Hubble Space Telescope and one with the infrared Spitzer Space Telescope in 2016. All seven are within 1 parsec of 42 Orionis and are pointing in the direction of the star, which is the common ionizing source.
The discovery of the proplyds in NGC 1977 was the first time that astronomers found an instance where a B-type star was causing the photoevaporation of a proplyd. The ultraviolet radiation from 42 Orionis is eroding the protoplanetary disks, while the star’s strong stellar winds are carving the shapes of the gas into cometary tails. Six of the seven proplyds show tails pointing away from the star. Two of them have clearly resolved central sources that are associated with disks of radii between 50 and 70 astronomical units.
In 2021, astronomers reported the discovery of a swift stellar jet from a newly formed star in NGC 1977. The young star Parengo 2042 (P2042) was detected with NASA’s Hubble Space Telescope. The star is shrouded in a disk of debris in which planets may form in the future. It is responsible for powering a jet of plasma that stretches 2 light-years across. The gas in the jet is ionized by the radiation of a nearby star, 42 Orionis.
While searching for stellar jets and planet-forming disks, Hubble also caught a Herbig-Haro object catalogued as HH 45 within NGC 1977. Herbig-Haro objects are small bright patches of nebulosity found around newly formed stars. They form when these stars eject narrow jets of partly ionized gas, which then collide with nearby dust and gas at several hundred kilometres per second. As they collide with clouds of dust and gas, the jets create bright shock waves.
The Running Man Nebula is part of Orion’s Sword, one of the several conspicuous asterisms in the constellation Orion. Orion’s Sword is formed by 42 Orionis in the Running Man Nebula, the Theta Orionis system in the Orion Nebula (Messier 42), and the multiple star system Iota Orionis (Hatysa).
The region of Orion’s Sword forms the Orion OB1c subgroup of the Orion OB1 association. The stars of the Orion OB1c group – 42 Orionis, Theta Orionis, and Iota Orionis – have an estimated age between 3 and 6 million years.
The Running Man Nebula is the northernmost point of light in Orion’s Sword, an asterism located just below the Belt of Orion. The nebula appears only 0.6 degrees north of the brighter and larger Orion Nebula (Messier 42).
Orion is visible for most of the year from both the northern and southern hemispheres. The constellation disappears below the horizon during the northern hemisphere early summer, only to reappear in the eastern sky before dawn in August.
Orion dominates the evening sky from November to February. The best time of the year to observe the Running Man Nebula, the Orion Nebula, and other deep sky objects in the constellation is during the month of January, when the Hunter appears higher in the sky in the evening.
Running Man Nebula – NGC 1977
|Right ascension||05h 35m 16.2s|
|Declination||−04° 47′ 07″|
|Apparent size||40 x 25 arcminutes|
|Names and designations||Running Man Nebula, NGC 1977, Sharpless 279, Sh2-279|