Astronomers Finally Catch a Nova Detonating on a White Dwarf as it's Happening

Artist impression of an exploding White Dwarf. Credit: University of Tubigen.

On July 7, 2020, the X-ray instrument eROSITA captured an astronomical event that – until then – had only been theorized and never seen. It saw the detonation of a nova on a white dwarf star, which produced a so-called fireball explosion of X-rays.

“It was to some extent a fortunate coincidence, really,” said Ole König from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), who led the team of scientists who have published a new paper on the discovery. “These X-ray flashes last only a few hours and are almost impossible to predict, but the observational instrument must be pointed directly at the explosion at exactly the right time.”

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If There are Dyson Spheres Around White Dwarfs, We Should be Able to Detect Them

Searching for Dyson spheres, rings, or swarms remains a preoccupation of many astronomers.  If there are any out there, they will eventually be found, and the person or research team to do so will go down in history for making one of the most momentous discoveries in the history of humanity.  If you’re interested in claiming that accolade for yourself, an excellent place to look may be around white dwarfs.  At least, that’s the theory put forward in a new paper by Benjamin Zuckerman, a now-retired professor of astrophysics at UCLA.  

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A New Kind of Stellar Explosion Has Been Discovered: Micronovae

The most energetic explosions in the Universe come from stars called supernovae. These galactic bombs have the energy of about 1028 mega-tons. After they detonate, the only thing left behind is either a neutron star or black hole. Another type of stellar explosion is known as a nova which has much less energy and covers the surface of a white dwarf.

Now, a team of astronomers recently discovered a new type of stellar explosion akin to supernovae and novae but with much less energy, and they’re calling it a micronova.

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Astronomers Discover a Strange new Star That Might be From the Collision Between two Dead Stars

With how many stars there are in our galaxy, there are sure to be plenty of different types of them.  But they still continue to amaze us with their differences and constantly challenge our models on how exactly they form.  Now a new class of stars was discovered by Dr. Klaus Werner of the University of Tübingen, and they are covered in different materials than expected.

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Planet Found in the Habitable Zone of a White Dwarf

An artist’s impression of the white dwarf star WD1054–226 orbited by clouds of planetary debris and a major planet in the habitable zone. Credit Mark A. Garlick / markgarlick.com Licence type Attribution (CC BY 4.0)

Most stars will end their lives as white dwarfs. White dwarfs are the remnant cores of once-luminous stars like our Sun, but they’ve left their lives of fusion behind and no longer generate heat. They’re destined to glow with only their residual energy for billions of years before they eventually fade to black.

Could life eke out an existence on a planet huddled up to one of these fading spectres?

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Astronomers Discover a Totally New Kind of Nebula

Discovery image of the nebula. For this image, 120 individual exposures had to be combined to obtain a total exposure time of 20 hours. The images were taken over several months from Brazil. Image Credit: Maicon Germiniani

Most Universe Today readers are familiar with nebulae. They’re gaseous structures lit up with radiation from nearby stars, and they’re some of nature’s most beautiful forms.

With the help of amateur astronomers who laid the groundwork, an international team of astronomers have discovered a new type of nebulae around binary stars that they’re calling galactic emission nebulae.

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From the way These Stars Look, a Supernova is Inevitable

Sometimes loud explosions are easier to deal with when you know they’re coming.  They are also easier to watch out for.  So when astronomers from the University of Warwick found a rare tear-drop shaped star, known as HD265435, they knew they were looking at a potential new supernova waiting to happen.  The only caveat – it might not actually happen until 70 million years from now.

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White Dwarf Measured Before it Exploded as a Supernova

Artist's impression of a supernova remnant. Credit: ESA/Hubble

Type Ia supernovae are an important tool for modern astronomy. They are thought to occur when a white dwarf star captures mass beyond the Chandrasekhar limit, triggering a cataclysmic explosion. Because that limit is the same for all white dwarfs, Type Ia supernovae all have about the same maximum brightness. Thus, they can be used as standard candles to determine galactic distances. Observations of Type Ia supernova led to the discovery of dark energy and that cosmic expansion is accelerating.

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How can White Dwarfs Produce Such Powerful Magnetic Fields?

Illustration of the internal layers of a white dwarf star. Credit: University of Warwick/Mark Garlick

White dwarfs have some surprisingly strong magnetic fields, and one team of astronomers may have finally found the reason why. When they cool, they can activate a dynamo mechanism similar to what powers the Earth’s magnetic field.

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