Posted by New Delhi: The Hubble Space Telescope was deployed on 24 April, 1990. To celebrate its 34th anniversary, the flagship deep space observatory has captured an image of the Little Dumbbell Nebula, also known as Messier 76 or M76. The nebula is located at a distance of 3,400 lightyears in the circumpolar constellation of Perseus. The name is a reference to the two-lobed structure of the nebula.
M76 is a planetary nebula, which means that it is the exploded remains of a dead star. The expanding shell of glowing gases were ejected from the violent end of a dying red giant star, that is in the process of collapsing into a white dwarf, a dense stellar remnant that continues to burn after the death of a star. Planetary nebulae are not planets, but the name has stuck because they resembled planets when observed from early low-power telescopes in the 1700s.
Hot stellar remnant
The ring of gas and dust ejected by the collapsing star were probably sculpted by a binary companion. The hypothetical companion is not seen in the Hubble images, suggesting that it was consumed by the central star. The disc may contain further evidence of stellar cannibalism. The primary star is among the hottest stellar remnants known, with a temperature 138870°C, about 24 times that of the Sun.
NGC 3132, another planetary nebula captured by Hubble. (Image Credit: NASA/ESA/STScI).
The hot gases escaping from above and below the belt along the rotation axis of the star, are pinched off by the disk, and are being propelled by winds from the dying star. The outflows are travelling at over 3.2 million kilometres an hour, fast enough to make the hop between the Earth and the Moon in around seven minutes. The stellar wind is ploughing in to cooler, slower moving gas ejected at an earlier stage in the life of the star. The energetic outpourings from the forming white dwarf is causing the gases in the nebula to glow.
A brief history of Hubble
The Hubble Space Telescope was authorised for construction by the US Congress in 1977, and was named in honour of the eminent American Astronomer Edwin Hubble, who discovered that there were islands of stars peppered across the cosmos that we now understand as galaxies, came up with a system for classifying galaxies, and was able to determine that the universe was expanding.
The first image captured by Hubble was to demonstrate the precision of the instrument compared to ground based observatories, and to focus the instrument. (Image Credit: NASA/ESA/STScI).
The crew of the Space Shuttle Discover deployed the telescope on 24 April, 1990, ushering in a new era of astronomy that was free from the disturbances caused by the atmosphere. Hubble is a large reflecting telescope with a 2.4 metre primary mirror. There are a pair of cameras and a pair of spectrographs on board. The telescope has been upgraded and maintained many times over the course of its operation.
The legacy of Hubble
Hubble has transformed our understanding of the universe. Hubble has been able to confirm that the expansion of the universe is accelerating instead of slowing down. Hubble was used to investigate globular clusters that appear as single stars from ground based observatories, and investigated stellar nurseries, dense clouds of gas and dust where new stars are being formed.
Astronomers have been able to study galaxies across time, providing evidence for the hierarchical assembly of galaxies. Hubble has also improved our understanding of galaxy interactions and evolution. Through gravitational lensing, observations made by Hubble have been used to map the distribution of dark matter. The precise measurement of the Hubble constant, or the rate at which the universe is expanding has helped scientists estimate the age of the universe, about 13.8 billion years.
Hubble has helped astronomers better understand the interactions between galaxies. (Image Credit: NASA/ESA/STScI).
Hubble has also probed the cores of distant galaxies, providing evidence for supermassive black holes, and has identified the progenitor stars of Type Ia supernovae, which are essential for measuring cosmic distances. Hubble’s observations of distant quasars have shed light on the earliest cosmic epochs. In the Hubble Deep Field surveys, the telescope was randomly pointed to dark patches in the sky, revealing a number of hidden celestial objects.
Those interested in knowing more about how important Hubble is to modern times can do so by playing a tabletop RPG game released by NASA called The Lost Universe, which features a timeline in a parallel universe where Hubble does not exist. Hubble is expected to continue exploring the universe till at least the end of the decade, at times in tandem with the James Webb Space Telescope.