Our Sun will someday run out of fuel. Here’s what it will look like when that happens.
The fate of our Sun is unambiguous, determined solely by its mass.
If all else fails, we can be certain that the evolution of the Sun will be the death of all life on Earth. Long before we reach the red giant stage, stellar evolution will cause the Sun’s luminosity to increase significantly enough to boil Earth’s oceans, which will surely eradicate humanity, if not all life on Earth. (OLIVERBEATSON OF WIKIMEDIA COMMONS / PUBLIC DOMAIN)
Too small to go supernova, it’s still massive enough to become a red giant when its core’s hydrogen is exhausted.
As the Sun becomes a true red giant, the Earth itself may be swallowed or engulfed, but will definitely be roasted as never before. The Sun’s outer layers will swell to more than 100 times their present diameter.(WIKIMEDIA COMMONS/FSGREGS)
As the inner regions contract and heat up, the outer portions expand, becoming tenuous and rarified.
Near the end of a Sun-like star’s life, it begins to blow off its outer layers into the depths of space, forming a protoplanetary nebula like the Egg Nebula, seen here. Its outer layers have not yet been heated to sufficient temperatures by the central, contracting star to create a true planetary nebula just yet. (NASA AND THE HUBBLE HERITAGE TEAM (STSCI / AURA), HUBBLE SPACE TELESCOPE / ACS)
The interior fusion reactions generate intense stellar winds, which gently expel the star’s outer layers.
The Eight Burst Nebula, NGC 3132, is not well-understood in terms of its shape or formation. The different colors in this image represent gas that radiates at different temperatures. It appears to have just a single star inside, which can be seen contracting down to form a white dwarf near the center of the nebula. (THE HUBBLE HERITAGE TEAM (STSCI/AURA/NASA))
Single stars often shed their outer layers spherically, like 20% of planetary nebulae.
The spiral structure around the old, giant star R Sculptoris is due to winds blowing off outer layers of the star as it undergoes its AGB phase, where copious amounts of neutrons (from carbon-13 + helium-4 fusion) are produced and captured. The spiral structure is likely due to the presence of another large mass that periodically orbits the dying star: a binary companion. (ALMA (ESO/NAOJ/NRAO)/M. MAERCKER ET AL.)
Stars with binary companions frequently produce spirals or other asymmetrical configurations.
When our Sun runs out of fuel, it will become a red giant, followed by a planetary nebula with a white dwarf at the center. The Cat’s Eye nebula is a visually spectacular example of this potential fate, with the intricate, layered, asymmetrical shape of this particular one suggesting a binary companion. (NASA, ESA, HEIC, AND THE HUBBLE HERITAGE TEAM (STSCI/AURA); ACKNOWLEDGMENT: R. CORRADI (ISAAC NEWTON GROUP OF TELESCOPES, SPAIN) AND Z. TSVETANOV (NASA))
But the most common shape for planetary nebulae is a bipolar morphology, containing two opposing jets.
The Twin Jet nebula, shown here, is a stunning example of a bipolar nebula, which is thought to originate from either a rapidly rotating star, or a star that’s part of a binary system when it dies. We’re still working to understand exactly how our Sun will appear when it becomes a planetary nebula in the distant future. (ESA, HUBBLE & NASA, ACKNOWLEDGEMENT: JUDY SCHMIDT)
The leading explanation is that many stars rotate rapidly, which generates large-scale magnetic fields.
Known as the Rotten Egg Nebula owing to the large presence of sulfur found inside, this is a planetary nebula in the earliest stages, where it is expected to grow significantly over the coming centuries. The gas being expelled is moving at an incredible speed of about 1,000,000 km/hr, or about 0.1% the speed of light. (ESA/HUBBLE & NASA, ACKNOWLEDGEMENT: JUDY SCHMIDT)
Those fields accelerate the loosely-held particles populating the outer stellar regions along the dying star’s poles.
The Ant Nebula, also known as Menzel 3, is showcased in this image. The leading candidate explanation for its appearance is that the dying, central star is spinning, which winds its strong magnetic fields up into shapes that get entangled, like spaghetti twirled too long with a giant fork. The charged particles interact with those field lines, heating up, emitting radiation, and then get ejected, where they’ll disappear off into interstellar space. (NASA, ESA & THE HUBBLE HERITAGE TEAM (STSCI/AURA); ACKNOWLEDGMENT: R. SAHAI (JET PROPULSION LAB), B. BALICK (UNIVERSITY OF WASHINGTON))
NASA’s Hubble Space Telescope delivers the most spectacular images of this natural phenomenon.
Nitrogen, hydrogen and oxygen are highlighted in the planetary nebula above, known as the Hourglass Nebula for its distinctive shape. The assigned colors distinctly show the locations of the various elements, which are segregated from one another. (NASA/HST/WFPC2; R SAHAI AND J TRAUGER (JPL))
By assigning colors to specific elemental and spectral data, scientists create spectacular visualizations of these signatures.
The nebula, officially known as Hen 2–104, appears to have two nested hourglass-shaped structures that were sculpted by a whirling pair of stars in a binary system. The duo consists of an aging red giant star and a burned-out star, a white dwarf. This image is a composite of observations taken in various colors of light that correspond to the glowing gases in the nebula, where red is sulfur, green is hydrogen, orange is nitrogen, and blue is oxygen. (NASA, ESA, AND STSCI)
The cold, neutral gas will be boiled off by the central white dwarf in just ~10,000 years.
The Helix Nebula may appear to be spherical in nature, but a detailed analysis has revealed a far more complex structure. By mapping out its 3D structure, we learn that its ring-like appearance is merely an artifact of the particular orientation and time at which we view it. Nebulae such as these are short-lived, lasting for only about 10,000 years until they fade away. (NASA, ESA, C.R. O’DELL (VANDERBILT UNIVERSITY), AND M. MEIXNER, P. MCCULLOUGH, AND G. BACON ( SPACE TELESCOPE SCIENCE INSTITUTE))
In approximately 7 billion years, our Sun’s anticipated death should proceed in exactly this manner.
This planetary nebula may be known as the ‘Butterfly Nebula’, but in reality it’s hot, ionized luminous gas blown off in the death throes of a dying star. The outer portions are illuminated by the hot, white dwarf this dying star leaves behind. Our Sun is likely in for a similar fate at the end of its red giant, helium-burning phase. (STSCI / NASA, ESA, AND THE HUBBLE SM4 ERO TEAM)
Mostly Mute Monday tells an astronomical or scientific story in images, visuals, and no more than 200 words. Talk less; smile more. Ethan Siegel is the author of
Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.