To celebrate the 29th anniversary of the NASA/ESA Hubble Space Telescope, launched on April 24, 1990, astronomers released this spectacular image of the Southern Crab Nebula. As can be clearly seen, the nebula has two intriguing nested hourglass-shaped structures, which bear some resemblance to crab legs. The structures were sculpted by a pair of aging stars engaged in a cosmic waltz 10,700 light years away.
The image is a composite of multiple observations, taken with different color filters, by Hubble’s Wide Field Camera 3 in March, 2019. The colors correspond to the glowing gases in the nebula - red is sulfur, green is hydrogen, orange is nitrogen, and blue is oxygen.
Here is an animation from HubbleESA, which takes us on a 10,700 light year journey into the heart of the nebula.
The Southern Crab Nebula
The Southern Crab Nebula or Hen 2-104 is a nebula, located about 10,700 light-years from Earth in the southern hemisphere constellation of Centaurus. The image shown is 4.4 light years wide. (Source hubblesite.org/...)
At the center of the galaxy is a binary star system, consisting of an aging red giant star and a burned-out white dwarf remnant, locked in a slow orbital waltz, circling each other every 100 years or so. Each star is estimated to have a mass roughly equal to that of the Sun. The bloated red giant star is exhausting its nuclear fuel and is shedding its outer layers in a powerful stellar wind. Some of this ejected material is attracted by the gravity of the companion white dwarf. Gas continues to build up on the surface of the white dwarf until it reaches a critical mass and causes an eruption. A flat accretion disk of gas between the stars constricts the outflow of gas so that it only speeds away above and below the disk. The result is an hourglass shape in three dimensions; when seen in two dimensions, the bubbles of gas and dust appear brightest at the edges, giving the illusion of crab leg structures.
The outer and inner hours-glass shapes were likely created in two separate outbursts that occurred several thousand years apart. It is thought that the process that creates these eruptions will continue and create additional expanding hourglass-shaped nebulae.
illuminateduniverse.org/… notes that the Southern Crab Nebula is a proto-planetary nebula, while its northern (more widely known) namesake, simply called the Crab Nebula, is a supernova remnant. Both are the result of the dying stages of stars, but the southern one is expelling its material in a wind, while the northern one did so in a titanic explosion.
Eventually, the red giant will collapse to become a white dwarf. After that, the surviving pair of white dwarfs will continue their dance and illuminate a shell of gas called a planetary nebula.
FYI — our own Sun will turn into a red giant in about 5 billion years. As a red giant, the Sun will grow so large that it will engulf Mercury, Venus, and probably Earth. Life would have been snuffed out from Earth long before then.
Crab, Spider, Butterfly or Moth?
The shape reminds people of various creatures besides the crab. One can see why the nebula was named after a crustacean from this 1989 image taken by the 2.2 metre telescope at La Silla in Chile.
Hubble Anniversaries
Hubble anniversaries are celebrated around the 24th of April each year. Around this time, the Hubble team captures a special anniversary image of a particularly beautiful and meaningful celestial object. en.wikipedia.org/… has the list of anniversary images from 2005 till 2018.
Here is the anniversary image from 2018, which we covered in a diary in April 2018 -
This 21st anniversary rose-like image of two interacting galaxies called Arp 273 from 2011 is exquisitely beautiful -
The Hubble Space Telescope
Hubble was launched 29 years ago on April 24, 1990 at 08:33:51 a.m. EDT, aboard the space shuttle Discovery. After five servicing missions, between 1993 and 2009, Hubble is still going strong and is expected to last beyond 2030. Even today, it outshines other space and ground based telescopes due to its unique ability to see in near-ultraviolet, visible and near-infrared light from its vantage point high above the Earth’s atmosphere.
After numerous delays, its successor, the James Webb Space Telescope (JWST), is scheduled to be launched in March 2021.
Here are some interesting nuggets of info. about Hubble —
- Hubble’s main mirror is 2.4-meters in diameter (JWST has a 6.5-meter-diameter segmented mirror)
- Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra.
- The Hubble spacecraft was manufactured by Lockheed; the optics and Fine Guidance Sensors were designed by Perkin-Elmer.
- Hubble has so far made more than 1.5 million observations of more than 43 500 celestial objects. www.spacetelescope.org/...
- Hubble data was initially stored on the spacecraft using tape recorders, which were replaced by solid state storage during servicing missions 2 and 3A.
- Hubble generates about a terabyte of new data per year. A total of 153 terabytes of data have been generated so far.
- Hubble circles Earth in a low earth orbit every 95 minutes at an altitude around 540 km.
- As of spring 2018, the telescope had made more than 163,500 trips around our planet traveling over 6.4 billion km.
- The farthest galaxies imaged by Hubble are an astronomical 13.2 billion light years away, galaxies that formed a mere 450 million years after the big bang.
- There are proposals on the drawing board for future servicing missions to extend the life and capabilities of Hubble.
The universe became a lot “bigger”, thanks to Hubble.
Hubble Servicing and Repair
Hubble is the only telescope designed to be serviced in space. After launch in 1990, five Space Shuttle missions were used to repair, upgrade, and replace systems on the telescope, including all five of the main instruments.
NASA has a new mini-series on Hubble repair, with a new episode every Tuesday, starting on April 16.
Epilogue
Over the past 29 years, the space telescope's breakthrough discoveries have revolutionized nearly all fields of astronomy and astrophysics. The Hubble telescope is a symbol of humanity’s ingenuity and its quest to understand the universe and our place in it.
The James Webb Space Telescope (JWST), which will be launched in 2021 will be able to peer deeper and farther, in space and time, building on Hubble’s success.
Hopefully, Hubble, like the Energizer bunny, will keep on going and going … and continue to bring us knowledge and beauty, and to inspire new generations of scientists, even though much of it is lacking in these trying times of trump.
What are your memories of Hubble? Of the initial days when the design flaws were discovered, the subsequent repair missions and the wonderful science and images it has generated over the years? What do you think our interest and investment in exploring space? Should we invest more energy and funds in space exploration or should we focus on the sorry state of our own planet?
Further Reading
- Hubble Celebrates 29th Anniversary with a Colorful Look at the Southern Crab Nebula — www.nasa.gov/...
- Hubble Telescope — hubblesite.org
- Hubble Wiki — en.wikipedia.org/...
- Galaxy and Nebulae photo galleries — hubblesite.org/… hubblesite.org/…
- HubbleESA at YouTube
- Southern Crab Nebula — en.wikipedia.org/…
- Hen 2–104: a close-up look at the Southern Crab — www.aanda.org/...
- Galaxies and Nebulae by Hubble (2016) — www.dailykos.com/…
- Galaxies and Nebulae by Hubble (2017) — www.dailykos.com/…
- The Lagoon Nebula — Celebrating Hubble Telescope's 28th anniversary (April 2018) — www.dailykos.com/…
- Celestial Fireworks (July 4, 2018) www.dailykos.com/…
- A Deeper Look at the First Ever Image of a Black Hole — www.dailykos.com/...