Tuesday, 26 March 2013

Triggering the birth of stars

New stars are forming all the time in our Galaxy. Stars form in dense gas clouds such as this one known as the 'Elephant Trunk Nebula' in the constellation Cepheus, about 2400 light years away from Earth.
Image taken using the Wide Field Camera (WFC) on the Isaac Newton Telescope (INT) in La Palma. Image compiled from data in three different filters, broad-band r or 'red' (green channel), i' or 'infra-red' (blue channel) and a narrow-band H-Alpha filter (red channel). Data combined and adjusted using Photoshop.
Image Credit: Nick Wright (SAO / Herts) & Geert Barentsen (Armagh / Herts)
Stars form when dense clumps of gas build up and then collapse under their own gravity. One way in which these clumps are believed to arise is when ultraviolet radiation from a massive star ionizes and compresses a gas cloud and creates the conditions necessary for stars to form. This image shows a bright ionization front being created by ultraviolet radiation from a massive star to the left of the image.

By measuring the ages of stars across this image, scientists found that the stars were younger the further they were from the massive star, with the youngest stars found deep within the 'elephant trunk' where only infrared light can be seen in this image. This suggests that the formation of these stars was 'triggered' by the ionization front that has slowly been moving across the gas cloud. This process is thought to be occurring across our entire Galaxy with the formation of new stars being continually triggered all the time.

References: Barentsen et al. 2011 and Drew et al. 2005.

Guest post by Dr Nick Wright, Royal Astronomical Society (RAS) Fellow at the University’s Centre for Astrophysics Research

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