The Boomerang Nebula is a protoplanetary nebula located 5,000 light-years away from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

in the constellation Centaurus. It is also known as the Bow Tie Nebula and catalogued as LEDA 3074547. The nebula's

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

is measured at making it the coolest natural place currently known in the Universe. The Boomerang Nebula is believed to be a

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or ''galaxy'', although, broadly speaking ...

evolving toward the

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelate ...

phase. It continues to form and develop due to the outflow of gas from its core where a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in its late stage life sheds mass and emits starlight illuminating dust in the nebula. Millimeter scale dust grains mask portions of the nebula's center so most escaping visible

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

is in two opposing lobes forming a distinctive hourglass shape as viewed from Earth. The outflowing gas is moving outwards at a speed of about 164 km/s and expanding rapidly as it moves out into

space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consi ...

; this gas expansion results in the nebula's unusually low

. Keith Taylor and Mike Scarrott called it the "Boomerang Nebula" in 1980 after observing it with the

Anglo-Australian telescope The Anglo-Australian Telescope (AAT) is a 3.9-metre equatorially mounted telescope operated by the Australian Astronomical Observatory and situated at the Siding Spring Observatory, Australia, at an altitude of a little over 1,100 m. In 200 ...

at the

Siding Spring Observatory Siding Spring Observatory near Coonabarabran, New South Wales, Australia, part of the Research School of Astronomy & Astrophysics (RSAA) at the Australian National University (ANU), incorporates the Anglo-Australian Telescope along with a col ...

. Unable to view it with great clarity, the astronomers saw merely a slight asymmetry in the nebula's lobes suggesting a curved shape like a

boomerang A boomerang () is a thrown tool, typically constructed with aerofoil sections and designed to spin about an axis perpendicular to the direction of its flight. A returning boomerang is designed to return to the thrower, while a non-returning ...

. The nebula was photographed in detail by the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...

in 1998 revealing a more symmetric hourglass shape. In 1995, using the 15-metre Swedish-ESO Submillimetre Telescope in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

, astronomers measured its temperature as −272.15 °C. This makes it the coldest place in the Universe found so far, besides laboratory-created temperatures. Even the −270 °C background glow from the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

is warmer than the

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

. It is the only naturally occurring object found so far that has a temperature lower than the

background radiation Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources. Background radiation originates from a variety of source ...

. In 2013, observations of the ALMA radio interferometer revealed other features of the Boomerang Nebula. The visible double lobe of the Boomerang Nebula was observed to be surrounded by a larger spherical volume of cold gas seen only in sub-millimeter radio wavelengths. The nebula's outer fringes appear to be gradually warming. As of mid-2017, it is believed that the

at the center of the nebula is a dying

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around o ...

Gallery

File:True shape of the Boomerang.jpg, Boomerang Nebula as seen by ALMA in 2017. File:Boomerang nebula - ALMA-HST-- Potw1724a.tif, From 2017 ALMA release File:Boomerang HST big.jpg, This Hubble image was recorded using polarizing filters (analogous to polarized

sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names Sunglasses#Other names, below) are a form of Eye protection, protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damagin ...

) and color-coded by the angle associated with the polarized light. File:Boomerang Nebula.png, Red filter applied to monochromatic 2013 ALMA data

References

External links

* NRAO Boomerang Nebul

* *
The Boomerang Nebula - The Coolest Place in the Universe?
European Space Agency, ESA, 20 February 2003
Hubble's View of the Boomerang Nebula
13 September 2005; see als
Scattered Light from the Boomerang NebulaSIMBAD
Coordinates and Scientific data. January 4, 2007. {{DEFAULTSORT:Boomerang Nebula Protoplanetary nebulae Centaurus (constellation) Stellar evolution Nebulae