NAOJ: ALMA Spots Metamorphosing Aged Star

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ALMA Spots Metamorphosing Aged Star
ALMA | NAOJ | NRAO | ESO | 2020 Mar 05

ALMA image of the old star system W43A. The high velocity bipolar jets ejected from the central aged star are seen in blue, low velocity outflow is shown in green, and dusty clouds entrained by the jets are shown in orange. Credit: ALMA (ESO/NAOJ/NRAO), Tafoya et al.

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An international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has captured the very moment when an old star first starts to alter its environment. The star has ejected high-speed bipolar gas jets which are now colliding with the surrounding material; the age of the observed jet is estimated to be less than 60 years. These features help scientists understand how the complex shapes of planetary nebulae are formed.

Sun-like stars evolve to puffed-up Red Giants in the final stage of their lives. Then, the star expels gas to form a remnant called a planetary nebula. There is a wide variety in the shapes of planetary nebulae; some are spherical, but others are bipolar or show complicated structures. Astronomers are interested in the origins of this variety, but the thick dust and gas expelled by an old star obscure the system and make it difficult to investigate the inner-workings of the process.

To tackle this problem, a team of astronomers led by Daniel Tafoya at Chalmers University of Technology, Sweden, pointed ALMA at W43A, an old star system around 7000 light years from Earth in the constellation Aquila, the Eagle.

Thanks to ALMA’s high resolution, the team obtained a very detailed view of the space around W43A. ...

Shaping the Envelope of the Asymptotic Giant Branch Star W43A with a Collimated Fast Jet ~ Daniel Tafoya et al

• Astrophysical Journal Letters 890(1):L14 (2020 Feb 10) DOI: 10.3847/2041-8213/ab70b8

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