NGC 6891 is a planetary nebula in the constellation Delphinus, the Dolphin, that is brilliant and uneven. This Hubble image shows an aspherical outer halo that is expanding faster than the interior nebula, as well as at least two ellipsoidal shells that are orientated differently.
In the nebula’s centre, filaments and knots encircle the central white dwarf star, as seen in this photograph. Astronomers believe that one of the shells is 4,800 years old and the outer halo is 28,000 years old based on their movements, implying a sequence of eruptions from the dying star at various periods.
Hubble analyzed NGC 6891 as part of his research into nebula distances and the formation and evolution of their structures. The central white dwarf star has ionised the gas in NGC 6891, removing electrons from the nebula’s hydrogen.
The charged electrons emit energy in the form of light when they By combining existing with hydrogen nuclei, they can go from a higher form to a reduced level, allowing the nebula’s gas to glow.
Structure and forms
Planetary nebulae, in comparison to diffuse nebulae (see H II area), are tiny objects with a radius of around 1 light-year and a gas mass of roughly 0.3 solar mass. The Helix Nebula (NGC 7293) in the constellation Aquarius is one of the biggest known planetary nebulae, with an angle of around 20 minutes of arc—roughly two-thirds the angular size of the Moon.
Planetary nebulae feature a 1,000-fold brighter surface and are significantly denser than most H II zones, with 1,000–10,000 atoms per cubic cm in their dense sections.
Some are so far distant that they seem brilliant when photographed directly, although the most notable examples have angular diameters of up to 20 minutes of arc across, with 10–30 minutes of the arc through. seconds of the arc being the norm.
Those with a bright disc have more regular shapes than chaotic H II areas, but there are frequently significant brightness changes throughout the disc. Planetaries often have regular, sharp outside edges, as well as a moderately regular inner boundary, giving them a ring-like appearance. Many feature two light lobes that resemble arcs of a circle and are joined by a bridge that resembles the letter Z.
Planetary nebulae’s distances
Because of the multitude of forms and masses of the ionized gas, determining the distance to any specific planetary nebula is difficult. The quantity of ionizing radiation that escapes from the centre star and the amount of hot low-density material that fills part of the volume but does not release significant radiation are both unknown. As a result, planetary nebulae are not a uniform group of objects.
Distances are calculated by taking measurements of around 40 items that have particularly advantageous features. Association with other objects whose distance can be measured independently, such as membership in a stellar cluster or association with a star with known attributes, are among the favourable features. For all others, statistical methods calibrated by these objects offer approximate estimates (around 30% inaccuracies) of distances.
Related: NASA’s Hubble Uncovers a Burst of Star Formation
Planetary nebulae evolution
A description of a planetary nebula’s development begins before the nebula’s own ejection. Before the ejection, the central star is a red giant, as will be detailed later. It loses mass rapidly, up to 0.01 Earth mass every day, in the form of a comparably slow-growing stellar wind during this period.
At this point, the red giant may be heavily veiled by dust that accumulates as a result of the wind’s heavy ingredients. The star’s and its wind’s natures eventually shift. Because the star’s hot core is exposed due to the loss of its overlying atmosphere, the star grows hotter.
Radiation from the blazing star ionises the inner gas. The ionisation zone travels gradually outward through what was formerly the stellar wind’s slowly moving material. The gas expands at a rate of around 30 kilometres (19 miles) per second. Because they are too tiny to exhibit a disc, nebulae at this stage are brilliant yet have starlike appearances as seen from Earth.
Its gas has a dense population of roughly one million atoms per cubed, although it becomes more dilute as it spreads. The nebula is surrounded by neutral hydrogen at this point. It seems to grow faster than the individual atoms of gas within it; as the density declines, the ionised shell “eats into” the neutral substance.
What are the three most exciting findings made by Hubble?
Contributed to the discovery of the universe’s age, which is today estimated to be 13.8 billion years, about three times the age of Earth. Nix and Hydra, Pluto’s two moons, were discovered. Aided in determining the rate of expansion of the universe. It was discovered that the centre of practically every massive galaxy is anchored by a black hole.
1. What exactly has Hubble discovered?
Hubble’s success is due in great part to its high altitude, which removes many of the effects that observers on the ground experience. In reality, due to the existence of chemicals like ozone that filter ultraviolet light in the higher atmosphere, UV astronomy is nearly difficult to accomplish from the ground. Hubble can collect some of the finest and deepest views of our Universe because of this, as well as the lack of turbulent air currents that cause stars to twinkle.
2. A chronology of Hubble discoveries
1993- When Hubble was originally launched, a mirror malfunction resulted in a substantial blurring effect, greatly limiting Hubble’s capacity to accomplish ground-breaking astronomy. Astronauts aboard the Endeavour space shuttle repaired a fault in Hubble’s mirror during the first servicing trip, bringing its optics to the astonishing degree of clarity we see today.
1994- Hubble captured images of a massive cloud of debris left behind by Comet Shoemaker-Levy 9 as it impacted Jupiter, a rare cometary collision. Hubble also saw the galaxy M87, which offered solid proof for the presence of Supermassive Black Holes in galaxies’ centres.
3. Who did the Hubble Space Telescope get its name from?
Edwin Hubble, an American astronomer, was honoured with the telescope’s name. Hubble, who was born in 1889, found that many objects formerly classed as nebulae and considered to be clouds of dust and gas were actually galaxies beyond the Milky Way. He made these observations between 1922 and 1923 at the Mount Wilson Observatory in California, using a 2.5-metre telescope, the Hooker telescope, which was the world’s biggest at the time.
Bottom line: The Hubble 12 planetary nebula is a juvenile planetary nebula with deep narrowband near-IR pictures and modest resolution spectra. These are the first images that clearly depict the planetary nebula’s complicated structure.
Resent posts
Author
