Astronomers Might Have Seen a Star Just Disappear. Turning Straight to a Black Hole Without a Supernova

This illustration shows what the luminous blue variable star in the Kinman Dwarf galaxy could have looked like before its mysterious disappearance. Credit: ESO/L. Calçada

Large stars have violent deaths. As they run out of hydrogen to fuse, the star’s weight squeezes its core to make it increasingly hot and dense. The star fuses heavier elements in a last-ditch effort to keep from collapsing. Carbon to Silicon to Iron, each step generating heat and pressure. But soon it’s not enough. The fusion even heavier elements don’t give the star more energy, and the core quickly collapses. The protons and neutrons of nuclei collide so violently that the resulting shock wave rips the star about. The outer layers of the star are thrown outward, becoming a brilliant supernova. For a brief time, the star shines brighter than its entire galaxy, and its core collapses into a neutron star or black hole. It was thought that all large stars end with a supernova, but new research finds that might not be the case.

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Astronomers Just Detected Either the Least Massive Black Hole, or a Strange and Massive Neutron Star

This graphic shows the latest merger compared to known black holes and neutron stars. Credit: LIGO-Virgo/ Frank Elavsky & Aaron Geller (Northwestern)

Black holes are the ultimate limit of gravitational collapse. Bring enough mass into a small enough volume, and its own weight will squeeze the mass into oblivion. All that remains is a warped pocket of space that it can trap anything that strays too close, even light.

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A Repeating Fast Radio Burst Has Been Found. It Flares for 4 Days and then Remains Silent for 12 Days

Artist’s impression of a fast radio burst traveling through space and reaching Earth. Credit: ESO/M. Kornmesser

Five hundred million light-years from Earth, there is a deeply unusual object. It is radio silent for 12 days, then erupts in bright radio bursts. These fast radio bursts occur randomly over four days, then the object goes silent for another 12 days. Astronomers have observed this object for 500 days, and the pattern always repeats, like clockwork. We still aren’t sure what the object is.

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Japanese Dark Matter Detector is Seeing a “Surprising Excess of Events”

The top PMT array with all of the electric cables. Credit: XENON Dark Matter Project

Dark matter is notoriously difficult to detect. So difficult that we haven’t detected it yet. Evidence for dark matter can be seen in everything from the warping of light near galaxies to the way galaxies cluster together. We are pretty sure dark matter is real, but we also know it can’t be made of any type of particle we currently know. But a new study has found some interesting data that could be evidence of dark matter, or not.

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Evidence is Building that the Standard Model of the Expansion of the Universe Needs some new Ideas

Artist's conception illustrating a disk of water-bearing gas orbiting the supermassive black hole at the core of a distant galaxy. Credit: Sophia Dagnello, NRAO/AUI/NSF

Once again a new measurement of cosmic expansion is encouraging astronomers to reconsider the standard cosmological model. The problem is the Hubble constant and dark energy. While we have a broad understanding of dark energy, pinning down the value of the Hubble constant has been a problem, since different measurements keep getting different results. Now a new study has been published which further complicates things.

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Neutron Stars Could Have a Layer of Exotic Quark Matter Inside Them

Illustration of a quark core in a neutron star. Credit: Jyrki Hokkanen, CSC - IT Center for Science

Neutron stars are strange things. They can form when gravity kills a star, crushing its remains into a dense ball the size of a small city. They are so dense that only quantum forces and the Pauli exclusion principle keeps it from collapsing into a black hole singularity. The interior of a neutron star is so dense that matter behaves in ways we still don’t fully understand.

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Is the Concept of a Habitable Zone Too Wide?

Planetary system comparison
This size and scale of the Kepler-452 system compared alongside our own solar system, plus another planetary system with a habitable-zone planet known as Kepler-186f. The Kepler-186 system has a faint red dwarf star and a planet whose orbit would fit inside the orbit of Mercury.

In our search for exoplanets, we have found more than three dozen potentially habitable worlds. It’s estimated that there are 8 to 20 billion potentially habitable, Earth-like worlds in our galaxy alone. But there is a big difference between potentially habitable and actually habitable, and scientists are starting to narrow their definitions.

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A New Test Confirms Dark Energy and the Expansion of the Universe

A map of galaxy clustering in the universe. Credit: Seshadri Nadathur

In the standard model of cosmology, dark energy fills the universe. It causes the universe to expand at an ever-increasing rate, and it makes up more than 70% of the cosmos. But there’s a problem. When we measure the rate of cosmic expansion in different ways, we get results that disagree with each other.

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Study of 200,000 Galaxies Reveals the Entire Universe Might Have Been Spinning in One Direction Early On

Some of the most dramatic events in the Universe occur when certain stars die — and explode catastrophically in the process. Such explosions, known as supernovae, mainly occur in a couple of ways: either a massive star depletes its fuel at the end of its life, become dynamically unstable and unable to support its bulk, collapses inwards, and then violently explodes; or a white dwarf in an orbiting stellar couple syphons more mass off its companion than it is able to support, igniting runaway nuclear fusion in its core and beginning the supernova process. Both types result in an intensely bright object in the sky that can rival the light of a whole galaxy. In the last 20 years the galaxy NGC 5468, visible in this image, has hosted a number of observed supernovae of both the aforementioned types: SN 1999cp, SN 2002cr, SN2002ed, SN2005P, and SN2018dfg. Despite being just over 130 million light-years away, the orientation of the galaxy with respect to us makes it easier to spot these new ‘stars’ as they appear; we see NGC 5468 face on, meaning we can see the galaxy’s loose, open spiral pattern in beautiful detail in images such as this one from the NASA/ESA Hubble Space Telescope.

Almost everything in the universe spins. Planets rotate on their axis, stars spin around black holes, and galaxies spin in great spiral structures. But what about the universe as a whole?

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Powerful Telescope Confirms There’s an Earth-Sized World Orbiting Proxima Centauri

Artist view of the surface of Proxima Centauri b. Credit: ESO/M. Kornmesser

The closest star to the Sun is a small red dwarf star known as Proxima Centauri. It is only 4.2 light-years away and is now known to have an Earth-sized planet in its habitable zone. That doesn’t mean there is life orbiting the nearest star, but its proximity should help us understand the possibilities.

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