From Ethan Siegel: “The Double Jet Death Of Sun-Like Stars”

From Ethan Siegel

May 30, 2016

Planetary Nebula M2-9, from the Hubble Space Telescope. Image credit: Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA/ESA.

When stars like our Sun, between 40% and ~800% of our mass, run out of hydrogen in their core, they start to die.

The bipolar planetary nebula PN Hb 12, the late stages of a dying Sun-like star. Image credit: NASA, ESA; Acknowledgement: Josh Barrington.

The core contracts and heats up, causing the outer layers to expand as the star becomes a helium-burning red giant.

The Egg Nebula, a proto-planetary nebula in the early stages of formation. Image credit: NASA / Hubble.

The intense stellar winds produced gently blow off the star’s outer layers.

The red rectangle nebula. Image credit: ESA / Hubble & NASA.

When the core runs out of helium to burn, the central region contracts to a white dwarf, producing intense ultraviolet light.

The Southern Crab Nebula (He2-104) in its entirety, as observed by the Hubble Space Telescope. Image credit: ESA / Hubble and NASA, STScI.

This light ionizes the atoms that had previously been blown off. As the electrons recombine with their ions, they emit light of various wavelengths.

Nitrogen, hydrogen and oxygen are highlighted in the planetary nebula above, known as the Hourglass Nebula for its distinctive shape. Image credit: NASA/HST/WFPC2 R Sahai and J Trauger (JPL).

Hydrogen tends to glow red, while oxygen, sulphur, sodium, carbon and nitrogen cover the greens, blues and yellows when shown in true color.

The Ant Nebula, also known as Menzel 3. Image credit: NASA, ESA & the Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Sahai (Jet Propulsion Lab), B. Balick (University of Washington).

Some 80% of planetary nebulae are asymmetrical, with the vast majority of those showing a bipolar form.

The Rotten Egg Nebula. Image credit: NASA / Hubble.

These twin jets emerge along the parent star’s rotational axis, where streams of material most likely flow outwards and collide with previously blown-off stellar layers.

Observations of active nebulae show that ~10 lunar masses worth of material are ejected each year, at speeds reaching 5% the speed of light.

See the full article here .

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“Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan