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Starts With A Bang

5 Better Candidates Than Betelgeuse For Our Galaxy’s Next Supernova

Despite Betelgeuse’s recent faintening and brightening, I’d bet on these stars instead.

Betelgeuse, a nearby red supergiant, will someday explode.

The black hole at the center of the Milky Way should be comparable in size to the physical extent of the red giant star Betelgeuse: larger than the extent of Jupiter’s orbit around the Sun. Betelgeuse was the first star of all beyond our Sun to be resolved as more than a point of light, but other red supergiants, such as Antares and VY Canis Majoris, are known to be larger. (A. DUPREE (CFA), R. GILLILAND (STSCI), NASA)

One of our brightest stars, its recent dimming portends an eventual supernova.

The constellation Orion as it would appear if Betelgeuse went supernova in the very near future. The star would shine approximately as brightly as the full Moon, but all the light would be concentrated to a point, rather than extended over approximately half a degree. (WIKIMEDIA COMMONS USER HENRYKUS / CELESTIA)

A “stellar burp” ejected matter, causing Betelgeuse’s temporary, routine faintening.

These four images show Betelgeuse in the infrared, all taken with the SPHERE instrument at the ESO’s Very Large Telescope. Based on the faintening observed in detail, we can reconstruct that a “burp” of dust caused the dimming. Although variability remains larger than it was previously, Betelgeuse has returned to its original, early-2019-and-before brightness. (ESO/M. MONTARGÈS ET AL.)

Meanwhile, these 5 Milky Way candidates could easily go supernova first.

The atmosphere of Antares, by temperature and size, as inferred from ALMA and VLA data. Whereas Betelgeuse is large, larger than Jupiter’s orbit around the Sun, the extent of Antares goes almost to Saturn as measured by the end of the upper chromosphere, but the luminous Wind Acceleration Zone goes all the way out almost to the extent of Uranus’s orbit. (NRAO/AUI/NSF, S. DAGNELLO)

1.) Antares. Closer and larger than Betelgeuse, massive Antares is ~11–15 million years old.

This simulation of a red supergiant’s surface, sped up to display an entire year of evolution in just a few seconds, shows how a “normal” red supergiant evolves during a relatively quiet period with no perceptible changes to its interior processes. There are multiple “dredge-up” periods where material from the core gets transferred to the surface, and this results in the creation of at least a fraction of the Universe’s lithium. (BERND FREYTAG WITH SUSANNE HÖFNER & SOFIE LILJEGREN)

This red supergiant should explode within ~10,000 years.

The Carina Nebula, with Eta Carina, the brightest star inside it, on the left. What appears to be a single star was identified as a binary back in 2005, and it’s led some to theorize that a third companion was responsible for triggering the supernova impostor event. (ESO/IDA/DANISH 1.5 M/R.GENDLER, J-E. OVALDSEN, C. THÖNE, AND C. FERON)

2.) Eta Carinae. This famous “supernova impostor” has brightened, historically, numerous times.

The ‘supernova impostor’ of the 19th century precipitated a gigantic eruption, spewing many Suns’ worth of material into the interstellar medium from Eta Carinae. High mass stars like this within metal-rich galaxies, like our own, eject large fractions of mass in a way that stars within smaller, lower-metallicity galaxies do not. Eta Carinae might be over 100 times the mass of our Sun and is found in the Carina Nebula, but other known stars are more than twice as massive. Some supernova impostors remain stable for centuries; others have been caught exploding after only a few years. (NASA, ESA, N. SMITH (UNIVERSITY OF ARIZONA, TUCSON), AND J. MORSE (BOLDLYGO INSTITUTE, NEW YORK))

Its remaining lifetime could span centuries, or merely years.

The Wolf-Rayet star WR 102 is the hottest star known, at 210,000 K. In this infrared composite from WISE and Spitzer, it’s barely visible, as almost all of its energy is in shorter-wavelength light. The blown-off, ionized hydrogen, however, stands out spectacularly. (JUDY SCHMIDT, BASED ON DATA FROM WISE AND SPITZER/MIPS1 AND IRAC4)

3.) WR 102. Wolf-Rayet stars represent the final evolutionary phases for massive stars expelling their outer layers.

The extremely high-excitation nebula shown here is powered by an extremely rare binary star system: a Wolf-Rayet star orbiting an O-star. The stellar winds coming off of the central Wolf-Rayet member are between 10,000,000 and 1,000,000,000 times as powerful as our solar wind, and illuminated at a temperature of 120,000 degrees. (The green supernova remnant off-center is unrelated.) Systems like this are estimated, at most, to represent 0.00003% of the stars in the Universe. (ESO)

WR 102 is the hottest: 210,000 K, foreshadowing a stellar cataclysm.

The red arrow points to WR 142: a single, X-ray emitting star at temperatures of 200,000 K. WR 142 shows an overabundance of oxygen in its spectrum, indicating that the star has cooked up elements up to oxygen in its core, and is well on its way to the iron catastrophe which will trigger the violent death of the star. (L. M. OSKINOVA, W.-R. HAMANN, A. FELDMEIER, R. IGNACE, Y-H. CHU AND ESA)

4.) WR 142. The second-hottest Wolf-Rayet star, WR 142’s demise is inevitable.

The Crescent Nebula in Cygnus is powered by the central massive star, WR 136, where the hydrogen expelled during the red giant phase is shocked into a visible bubble by the hot star at the center. As the star’s hydrogen and then helium layers are blown off, it heats up, and as it fuses through heavier successive elements, it gets hotter still. Unless mass loss is severe enough, a supernova will result. (WIKIMEDIA COMMONS USER HEWHOLOOKS)

Similarly hot, depleted, and oxygen-rich Wolf-Rayet candidates include WR 30a and WR 93b.

Two different ways to make a Type Ia supernova: the accretion scenario (L) and the merger scenario (R). The merger scenario is responsible for the majority of many of the heavy elements in the Universe, but the accretion mechanism is also responsible for Type Ia events. The system T Coronae Borealis is a red giant-white dwarf combo, where the white dwarf has a mass of 1.37 solar masses: perilously close to the Chandrasekhar limit. (NASA / CXC / M. WEISS)

5.) T Coronae Borealis. White dwarfs siphoning mass from red giants can trigger type Ia supernovae.

When a denser, more compact star or stellar remnant comes into contact with a less dense, more tenuous object, like a giant or supergiant star, the denser object can siphon mass off of the larger one, accreting it onto itself. If the mass exceeds a critical threshold governed by the Pauli Exclusion Principle, a cataclysmic explosion will occur. (DAVID A. AGUILAR (HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS))

T Coronae Borealis’s white dwarf now approaches this critical mass threshold.

When a white dwarf close to the Chandrasekhar mass limit accretes enough matter off of a binary companion, a runaway nuclear fusion reaction will get triggered. This will not only create a Type Ia supernova, but will destroy the white dwarf in the process. (NASA/ESA, A. FEILD (STSCI))

Similarly, 5 common “next supernova” candidates are relatively unlikely.

The Wolf-Rayet star WR 124 and the nebula M1–67 which surrounds it both owe their origin to the same originally massive star that blew off its outer layers. The central star is now far hotter than what came before, but WR 124 is not the hottest class of Wolf-Rayet star: those are the ones that are depleted of hydrogen and helium but heavily enhanced with oxygen. (ESA/HUBBLE & NASA; ACKNOWLEDGEMENT: JUDY SCHMIDT (GECKZILLA.COM))

V Sagittae, IK Pegasi B, γ Velorum, WR 124, and ρ Cassiopeiae all require additional steps.

When two stars or stellar remnants merge, they can trigger a cataclysmic reaction, including supernovae, gamma-ray bursts, or they can lead to the creation of a hotter, bluer more massive star. In the case of V Sagittae, however, it is not well-accepted that the stars will inspiral and merge later this century, despite recent assertions. (MELVYN B. DAVIES, NATURE 462, 991–992 (2009))

Our next supernova might deliver a multi-messenger trifecta:

  • neutrinos,
  • gravitational waves,
  • and light,

all together.

A supernova explosion enriches the surrounding interstellar medium with heavy elements. This illustration, of the remnant of SN 1987a, showcases how the material from a dead star gets recycled into the interstellar medium. In addition to light, we also detected neutrinos from SN 1987a. With the LIGO and Virgo detectors now functional, it’s possible that the next supernova within the Milky Way will yield a triple multi-messenger event, delivering particles (neutrinos), light, and gravitational waves all together. (ESO / L. CALÇADA)

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.

Starts With A Bang is written by Ethan Siegel, Ph.D., author of Beyond The Galaxy, and Treknology: The Science of Star Trek from Tricorders to Warp Drive.


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