Image credit: NASA, ESA and The Hubble Heritage Team (STScI/AURA); Acknowledgment: J. Biretta (STScI)

Key Takeaways:

  1. The Boomerang Nebula, located in the constellation Centaurus, is the coldest place in the universe with a temperature of just 1 Kelvin.
  2. It is a protoplanetary nebula formed by a dying red giant star shedding its mass to create clouds of dust and gas.
  3. The nebula is expanding at a rate of 164 km/s, and its extremely low temperature is a result of the gas from the central star continuing to expand.
  4. The unique hourglass shape of the nebula is caused by the central region being obscured by dust.
  5. Observations reveal a spherical volume of cold gas surrounding the visible double lobe, with the outer layers gradually warming.

The Boomerang Nebula, also known as the Bow Tie Nebula, is a remarkable celestial entity situated in the Centaurus constellation, about 5,000 light-years away from Earth. This protoplanetary nebula earned its reputation as the coldest place in the universe, boasting a frigid temperature of only 1 Kelvin, even colder than the faint glow of the Big Bang’s aftermath. Its creation can be attributed to a dying red giant star in the late stages of its life, which shed its mass, forming clouds of dust and gas, subsequently illuminated by the star’s light.

The Boomerang Nebula’s central star continues to expel material, causing outflowing gas to expand outward and perpetuating the nebula’s formation. Notably, the nebula’s expansion occurs at a staggering rate of 164 km/s, resulting in the loss of almost one and a half times the mass of the Sun in the past 1,500 years. This process is ten times faster than similar stars that expel gas. As the gas from the central star expands, it gives rise to the nebula’s extraordinary low temperature, marking it as a dying red giant at the heart of the formation.

The Boomerang Nebula’s captivating hourglass shape when viewed from Earth adds to its allure. This peculiar shape results from a doughnut-shaped dust cloud blocking the light radiating from the star’s equator, creating a double-lobed appearance. Moreover, a hollow cylindrical nebula envelops the dying star, possibly formed by jets of hydrogen or helium gas emanating from its poles, carving out a tunnel in the surrounding gas.

Named after its boomerang-like lobes, the nebula has intrigued astronomers for years. Originally thought to be a bow tie shape, NASA’s Hubble Space Telescope later revealed its true spherical nature. Recent observations using the ALMA radio interferometer have uncovered a larger spherical volume of cold gas surrounding the visible double lobe, with the outer layers showing signs of gradual warming.


A color-coded image of the Boomerang Nebula, as taken by the Hubble Space Telescope. Image credit: NASA


Image from Steve Bowers


Images were aligned based on coordinates. Images were stacked and drizzled
TGV + MMT denoise on each channel. RGB color combination. Arcsin H stretch. HDR multiscale transform. Curves transformation. MLT denoise. Unsharp Mask. Curves transformation. Credit: NASA/ESA/Hubble


The image was exposed for 1000 seconds through a green-yellow filter. The light in the image comes from starlight from the central star reflected by dust particles. Credit: European Space Agency, NASA


These colors simply don’t exist. The Hubble Space Telescope used the same color filter (0.5907 microns) for each shot and instead used different polarization filters. I applied each polarized image to the red, green, and blue color channels to get the image you see. NASA/Hubble Team/John Biretta/Kevin M. Gill


Credit: European Space Agency, NASA


Only color available is F606W. I used ACS/WFC F606W;CLEAR2L data marked as J97K01C8Q. Blueish color gradient colorize thing applied to the image instead. I tried to remove the cosmic rays but also probably got some dim stars so please forgive me for that. Credit: Brandon Pimenta


Credit: Judy Schmidt

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