Twenty-nine years ago, on April 24, 1990, the NASA/ESA Hubble Space Telescope was launched on the space shuttle Discovery. The telescope has since revolutionized how astronomers and the general public see the Universe by the spectacular images it provides from both a scientific and a purely aesthetic point of view. NASA’s Hubble Space Telescope has made more than 1.4 million observations of nearly 45,000 celestial objects. In its 29-year lifetime, the telescope has made more than 169,000 trips around our planet, totaling more than 4.2 billion miles.
Each year the telescope has been in space it dedicates a small portion of its precious observing time to take a special anniversary image, focused on capturing particularly beautiful and meaningful objects. This year’s image is the Southern Crab Nebula.
This peculiar nebula, which exhibits nested hourglass-shaped structures, has been created by the interaction between a pair of stars at its centre. The unequal pair consists of a red giant and a white dwarf. The red giant is shedding its outer layers in the last phase of its life before it too lives out its final years as a white dwarf. Some of the red giant’s ejected material is attracted by the gravity of its companion.
Cast-off material from the red giant is pulled onto the white dwarf and when it gets to be enough, it too ejects the material outwards in an eruption, creating the structures we see in the nebula. The red giant will eventually finish throwing off its outer layers and stop feeding its white dwarf companion. Prior to this, there may also be more eruptions, creating even more intricate structures, which astronomers were not always aware of.
First written about in 1967 but was assumed to be an ordinary star until 1989, this object was observed using telescopes at the European Southern Observatory’s La Silla Observatory. The resulting image showed a roughly crab-shaped extended nebula, formed by symmetrical bubbles of gas and dust.
These observations only showed the outer hourglass emanating from a bright central region that could not be resolved. It was not until Hubble observed the Southern Crab in 1998 that the entire structure came into view. The Southern Crab image revealed the inner nested structures, suggesting that the phenomenon that created the outer bubbles had occurred twice in the (astronomically) recent past.
Hubble observations have produced more than 153 terabytes of data, which are available for present and future generations of researchers. This new image from the Hubble Space Telescope of the Southern Crab Nebula adds to the story of an active and evolving object and contributes to the story of Hubble’s role in our evolving understanding of the Universe.
Credit: NASA, ESA, and STScI