NASA's Hubble Space Telescope recently revealed an astronomical occurrence, showing that the outer halo of gas is expanding more rapidly than the innermost portion of the nebula.
According to a Space.com report, the observations even captured shells of gas that are oriented in different directions. What's described as a tranquil cloud of gas belies a lot of activities "deep within the nebula."
Essentially, astronomers call NGC 6891 a "planetary nebula," a term that ascends from an old misidentification with planets when space telescope technology was in its early stage.
This planetary nebula is glowing in a new image from NASA's Hubble Space Telescope, as the observatory in assisting scientists in discovering more about how such gas clouds are forming and evolving.
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Wrapped Around a White Dwarf
Today, it's known that such nebulas are forming following explosions of a supernova that see gigantic stars shed gas. More so, a white dwarf remnant of the star stays behind, cooling lowly.
The high-definition imagery, as mentioned earlier, unveiled knots and fila, filaments wrapped around the white dwarf entrenched deep within the cloud.
In a statement, officials at NASA said, from their motions, astronomers approximate that the age of one of the shells is around 4,800 years old while the outer halo is roughly 28,000 years old, specifying a "series of outburst from the dying star different times."
The glowing coming from NGC 6891 occurs as the white dwarf stars are ionizing or stripping away electrons from the hydrogen gas surrounding them.
NASA also said that as the energized electrons return from their higher-energy state to a lower-energy condition by reintegrating with the hydrogen nuclei, they release energy in the form of light, causing the nebula's gas to glow.
At present, the Hubble Space Telescope is recovering from a synchronization glitch in October, and its instruments are gradually being brought back online.
In 2009, the Hubble Telescope was last serviced in person, and with the retirement of this shuttle, astronauts can no longer access it. The said space telescope, 31 years of age, has plenty of archival data to process.
Interesting Facts About NGC 6891
Universe Guide describes NGC 6891 as a "Planetary Nebula" in the assemblage of Delphinus. It is referred to as such, in the New General Catalogue, a list of objects in the deep space that was compiled in 1988 by John Lis Dreyer in an update to John Herschel's previous catalog.
The location of the NGC 6891 is 20 15 08.8436589777, RA, and +12 42 15.585470301, Dec. Essentially, the Right Ascension is an object's angular distance along the celestial equator from March Equinox.
Furthermore, as a rough guide, the site is located in the arrangement of Pisces. If the number is negative, it is the March Equinox's "west" part.
Lastly, the Declination is the object's angle from the celestial equator. In connection to this, a negative value specifies that it is in the southern hemisphere.
Information about the planetary nebula is explained in Cosmoknowledge's YouTube video below:
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