Boomerang Nebula

The Boomerang Nebula (canonical name <ref name=WakelyHoran/>) is a pulsar-wind<ref name=GREENG106/> bipolar reflection<ref name=101093mnras1932321>Template:Cite journal</ref><ref name=BollesScattered>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> nebula<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> located approximately 5,000 light-years from Earth in the constellation Centaurus.<ref name=BollesScattered/><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Holmberg & Lauberts (Uppsala Observatory) and Schuster & West (European Southern Observatory (ESO)) <ref>Template:Cite journal</ref> in their survey of 1976 or earlier discovered the existence of an object at the location.<ref name=101093mnras1932321/> Before or during 1978 I.S. Glass <ref name=1979MNRAS> Template:Cite journal </ref> discovered the object as a nebula <ref name=SALÉR-RAMBERG>Template:Cite thesis</ref> with G. Wegner,<ref name=SALÉR-RAMBERG/><ref name=1979MNRAS/> both of South African Astronomical Observatory, from data of the ESO Quick Blue Survey.<ref name=1979MNRAS/> Wegner and Glass in their paper of 1979 mentioned a "butterfly" or "bow-tie" like shape.<ref name=1979MNRAS/> K. N. R. Taylor (University of New South Wales) and S. M. Scarrott (Durham University) made observations July 17, 1979 and named it after the boomerang.<ref name=101093mnras1932321/> Modelling of measurements of outflow of the nebula published 1997 by Sahai (Jet Propulsion Laboratory) and Nyman (ESO & Onsala Space Observatory) indicate kelvin (K) less than cosmic microwave background radiation (cmbr), so the most cold natural place currently known<ref name="Sahai & Nyman, 1997">Template:Cite journal</ref> in the observed Universe.

The central star is PSR~J2229+6114.<ref>Template:Cite journal</ref> The max-diametrical temperature of the central star is estimated to be 6000 K (by Wegner and Glass <ref name=1991A&A242247B>Template:Cite journal</ref> 1978 or earlier) <ref name=1979MNRAS/> or 7000 K (Bujarrabal & Bachiller before July 1990).<ref name=1991A&A242247B/>

The Boomerang Nebula is believed to be a star system evolving toward the planetary nebula phase. It continues to form and develop due to the outflow of gas from its core where a star in its late stage life sheds mass and emits starlight, illuminating dust in the nebula. Millimeter scale dust grains obscure portions of the nebula's center, so most escaping visible light is in two opposing lobes forming a distinctive hourglass shape as viewed by space telescope data on Earth. The outflowing gas at about 164 km/s expands rapidly into space; this gas expansion results in the nebula's unusual K.

Using observations from 1994 and 1995 with the 15-metre Swedish-ESO Submillimetre Telescope in Chile, the astronomers Sahai & Nyman concluded carbon monoxide (CO) molecules produced after stellar co-absorption in a binary system of the nebula which outflow as a gas wind were less kinetically excited than the local outer space (cmbr).Template:Efn Radiation transfer of cmbr into the CO parts Template:Efn of the nebula wind indicated those parts onlyTemplate:Efn must have a kelvin temperature state which is uniquely the least of any observed location in nature.<ref name="Sahai & Nyman, 1997"/><ref>Template:Cite news</ref>

The kinetic energy (KE) of the CO outflow is theorized Template:Efn as the product of common-envelope evolution,<ref name=Sahai6040102>Template:Cite journal</ref> which was a change in the outer environment (an envelope) of the dual orbital system of the binary system.<ref name=Ivanovaetal0159-013-0059-2/> The KE within the outflow is theorized as an environment forced out from the area of the orbital system of the larger star by the absorption of the lesser sized star into the core of the larger by terminal gravitational attraction.<ref name=Sahai6040102/> Cooling to sub cmbr temperature is by adiabatic expansion.<ref name=Sahaietal101088>Template:Cite journal</ref>

A succession of periodic observations from November 2011 (Atacama Large Millimeter Array) ending June 2012 (Australia Telescope Compact Array) with archived observations from Hubble (HST) (1998 & 2005) <ref name=Sahaietal101088/> revealed other features.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The nebula's visible double lobe was observed to be surrounded by a larger spherical region 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 star at the center of the nebula is a dying red giant.<ref name="rgb">Template:Cite journal</ref><ref>Archived at GhostarchiveTemplate:Cbignore and the Wayback MachineTemplate:Cbignore: {{#invoke:citation/CS1|citation |CitationClass=web }}Template:Cbignore</ref>

Gallery

ALMA (2017)

• True shape of the Boomerang.jpg
• Boomerang nebula - ALMA-HST-- Potw1724a.tif

HST

• Boomerang HST big.jpg

  Imaged using polarizing filters (analogous to polarized sunglasses) and color-coded by the angle associated with the polarized light.

• Boomerang Nebula.png

  Red filter applied to monochromatic data

External links

• NRAO Boomerang Nebula
• Template:Cite journal
• Template:Cite news
• The Boomerang Nebula - The Coolest Place in the Universe?, ESA, 20 February 2003
• Hubble's View of the Boomerang Nebula, 13 September 2005; see also Scattered Light from the Boomerang Nebula
• ESA/Hubble-Boomerang Nebula
• SIMBAD, Coordinates and Scientific data. January 4, 2007.