Nebulae are also amongst the biggest structures in the universe. They can be hundreds of light-years across, with their diffuse clouds of gas forming into imaginative and colorful shapes, allowing astronomers to let their imaginations run wild when naming some of them.
However, if there is a reason why nebulae that are named after insects resemble insects more closely than their land animal or aquatic counterparts, for instance, it is probably because some insects have such weird and unusual shapes themselves. Nonetheless, many nebulae are shaped by complex physical processes, and if some nebulae do turn out to look like insects, we have all the more reason to marvel at their fascinating shapes, forms, and structures.
Cocoon Nebula
- Nebula type: Combined reflection/emission nebula
- Constellation: Cygnus
- Coordinates: RA 21h 53m 28.7s | Dec. +47° 16′ 01″
- Distance: About 4,000 light-years
- Diameter: About 15 light-years
- Magnitude: 7.2
- Other designations: IC 5146, Caldwell 19, Sh 2-125
The Cocoon Nebula strongly resembles the cocoon of a silkworm, which in this case has a red, glowing hue as a result of hydrogen gas being excited by young, hot stars. Dust-reflected starlight can also be seen around the edge of the molecular cloud.
Another point of interest is the nearby dark nebula designated Barnard 168, which is evident because many of the stars immediately around the nebula are obscured by this dark cloud. Together, the Cocoon Nebula and Barnard 168 form an impressive complex, with the latter creating a long dark trail extending away from the bright cocoon.
Bug Nebula
- Nebula type: Planetary nebula
- Constellation: Scorpius
- Coordinates: RA 17h 13m 44.2s | Dec. −37° 06′ 16″
- Distance: About 4,000 light-years
- Diameter: More than 2 light-years
- Magnitude: 7.1
- Other designations: NGC 6302, PK 349+01.1, Butterfly Nebula, Sharpless 6, RCW 124, Gum 60, Caldwell 69
The Bug Nebula is notable for its extraordinarily complex structure. Its dying central star has an estimated surface temperature of about 250,000°C, making it one of the hottest known stars in the Milky Way. Despite its extreme temperature, the star itself is hidden from direct view by a dense band of dust.
As with other bipolar planetary nebulae, the “waist” of the Bug Nebula is constrained by a torus of dust that appears as a dark lane running across its center. This thick belt restricts the outflow of material around the star’s equator, helping to channel the expanding gas into the spectacular opposing lobes that give the nebula its insect-like appearance.
Tarantula Nebula
- Nebula type: Emission nebula and H II region
- Constellation: Dorado (Large Magellanic Cloud)
- Coordinates: RA 05h 38m 38s | Dec. −69° 05.7′
- Distance: About 160,000 light-years
- Diameter: More than 650 light-years
- Magnitude: 8
- Other designations: NGC 2070, 30 Doradus
It is not difficult to see the shape of a cosmic spider clinging to the leading edge of the Large Magellanic Cloud, especially in this image, which shows enormous and extended areas of star formation as the “legs” of the spider.
In reality, the Tarantula Nebula is the most active star-forming region in the Local Group of galaxies and the largest such region in our galactic neighborhood. It is also extraordinarily luminous; if it were as close to Earth as the Orion Nebula (M42), its glow would be bright enough to cast visible shadows.
The Tarantula contains the massive young star cluster NGC 2070, whose central concentration R136 contains some of the most massive and luminous stars known. The intense ultraviolet radiation and stellar winds from these stars help illuminate and sculpt the surrounding nebula.
Minkowski’s Butterfly
- Nebula type: Bipolar planetary nebula
- Constellation: Ophiuchus
- Coordinates: RA 17h 05m 37.9s | Dec. −10° 08′ 33″
- Distance: About 4,000 light-years
- Age: About 1,200 years
- Other designations: M2-9, Twin Jet Nebula, Butterfly Nebula
Minkowski’s Butterfly, better known as the Twin Jet Nebula, is a striking example of a bipolar planetary nebula. The central object is a binary system, and interactions within this system have helped channel material into the two enormous lobes visible on opposite sides of the nebula.
Measurements of the expanding lobes suggest that the stellar outburst responsible for them occurred about 1,200 years ago. Within the lobes, enormous jets of gas stream outward at speeds exceeding one million kilometers per hour, producing the remarkable symmetrical structure seen here.
Ant Nebula
- Nebula type: Planetary nebula
- Constellation: Norma
- Coordinates: RA 16h 17m 13.4s | Dec. −51° 59′ 10″
- Distance: About 8,000 light-years
- Diameter: About 2 light-years
- Magnitude: 13.8
- Other designations: Mz 3, ESO 225-9, Chamber of Horrors
While it is not difficult to see the shape of a common garden ant in this nebula, it is not so easy to determine the mechanisms that created its complex structure. The Ant Nebula consists of several nested bipolar components, including lobes, columns and cone-shaped features surrounding its central region.
Astronomers have proposed several explanations for this unusual geometry, including interactions within a binary system and highly collimated outflows from the central region. The precise mechanism responsible for producing all of the Ant Nebula’s nested structures remains an active subject of study.
Papillon Nebula
- Nebula type: High Excitation Blob (HEB)
- Location: Large Magellanic Cloud in Dorado
- Distance: About 170,000 light-years
- Diameter: About 2 light-years
- Other designations: N159-5, Papillon Nebula
This image shows yet another nebula named after a butterfly, but in this case it represents a rare class of compact star-forming regions known as High Excitation Blobs. These are small, dense regions of ionized gas associated with the formation of massive young stars in the Magellanic Clouds.
The Papillon lies within the much larger N159 star-forming complex. The butterfly-shaped structure itself spans only about 2 light-years, while the surrounding complex extends across more than 150 light-years.
The striking shape is thought to have been sculpted by energetic young stars embedded within the nebula, whose radiation and stellar winds interact with the surrounding gas and dust.
Red Spider Nebula
- Nebula type: Planetary nebula
- Constellation: Sagittarius
- Coordinates: RA 18h 05m 13.1s | Dec. −19° 50′ 35″
- Distance: Roughly 3,000–8,000 light-years
- Magnitude: 13.0
- Other designation: NGC 6537
The Red Spider Nebula is a striking bipolar planetary nebula whose hot central star drives powerful stellar winds into the surrounding material. These outflows have helped create the nebula’s elongated lobes and the intricate structures that give it its spider-like appearance.
The central star is extremely hot, although estimates of its precise temperature vary considerably. Its energetic radiation ionizes the surrounding gas, while the interaction between fast stellar winds and previously ejected material helps shape the nebula’s dramatic structure.
Butterfly Nebula
- Nebula type: Planetary nebula
- Constellation: Monoceros
- Coordinates: RA 07h 09m 22.5s | Dec. −00° 48′ 24″
- Distance: About 2,000 light-years
- Diameter: About 0.33 light-years
- Magnitude: 11.6
- Other designation: NGC 2346
Not to be confused with several other nebulae named after butterflies, this planetary nebula is located close to the celestial equator and is particularly interesting because a close binary star system lies at its center.
The two stars orbit each other every 16 days. Astronomers believe they were once more widely separated, but when one evolved into a red giant it expanded enough to engulf its companion. The companion then spiraled inward through the red giant’s outer envelope, helping eject material into a dense ring around the binary.
Later, a faster stellar wind from the exposed hot core expanded preferentially above and below this ring, inflating the two enormous lobes. This two-stage process is thought to have produced the distinctive butterfly shape seen today.