Astronomers observe ultra-massive white dwarfs with unique atmospheres

Astronomers Observe Ultra-massive White Dwarfs

Astronomers observe ultra-massive white dwarfs with unique atmospheres, astronomers have discovered an ultra-heavy white dwarf with a unique carbon-hydrogen mixed atmosphere. Astronomers have discovered an ultra-heavy white dwarf with a unique atmosphere of carbon and hydrogen. This star is approximately 150 light years away.

It has a mass of 1.14 solar masses and is probably produced by the fusion of two white dwarfs in a narrow binary system. In the process of fusion, the impression of two white dwarfs of an artist; Depending on the combined mass, the system can explode in a thermonuclear supernova or accumulate in a heavy white dwarf.

Image Credit: NASA/ ESA. An astronomer at the University of Warwick, said,” as we had never seen before. In the process of fusion, the impression of two white dwarfs of an artist; Depending on the joint mass, the system may explode in a thermonuclear supernova.

Or WD J0551 + 4135 is chained in a heavy white dwarf. You can expect to see an outer layer of hydrogen, sometimes helium, or just a mixture of helium and carbon. You don’t expect to see this combination of hydrogen and carbon, because there should be a thick layer of helium in the middle of the restriction.

When we saw it, it made no sense. WD J0551 + 4135 was first identified in the ESA data study for the Gaia star mapping spacecraft. Dr. Holland and his colleagues followed the spectroscopy with the William Herschel telescope. By breaking the light emitted by the star.

Astronomers were able to identify the chemical composition of their atmosphere and discovered that it contained unusually high levels of carbon. To solve the puzzle, the researchers spied to discover the true origin of the star.

White dwarfs are remnants of our own sun-like stars that have burned all their fuel and shed their outer layers. Most are relatively light, about 0.6 times the mass of our Sun, but it is in a solar mass of 1.14, about twice the average mass.

Despite being heavier than our Sun, it is compressed two thirds of the Earth’s diameter. The age of the white dwarf is also a clue. Older stars orbit faster than younger stars than the Milky Way, and the object moves more than 99% of other nearby white dwarfs with the same cooling age, suggesting that this star is older than it seems.

We have a composition that we can explain through normal stellar evolution, twice the average mass of a white dwarf and a kinematic age greater than the cold age. We are very sure how a star becomes a white dwarf and shouldn’t do it.

The only way to explain it is if it was created by merging two white dwarfs. The theory is that when a star in a binary system expands at the end of its life, it will wrap its mate, bringing its orbit closer to its orbit, reducing the first star. The same will happen when the second star extends.

In billions of years, the emission of gravitational waves will reduce the orbit forward to the point where the stars merge. While it is predicted that the white dwarf will merge, this would be particularly unusual. Most of the mergers in our galaxy will be between stars of different mass, while this fusion seems to be between two stars of equal size.

There is also a limit to how large the resulting white dwarf can be: more than 1.4 solar masses are believed to explode in a supernova, although it is possible that these explosions may occur at a slightly lower mass. So Tara is useful for demonstrate how heavy a white dwarf can grow and still survive.

Because the fusion process resumes the cooling of the star, it is difficult to determine how old it is. The white dwarf probably disappeared about 1.3 billion years ago, but the two original white dwarfs may have existed billions of years ago.

It is one of the few white dwarfs ever identified, and the only one through its creation. Dr. “It’s not that there are many white dwarfs, but more than that you would expect to see if some of them are formed by fusion,” said Hollands.

In the future we can use a technique to learn about the basic structure of white dwarfs with stellar vibrations, which will be an independent method to confirm that this star formed from a fusion. Perhaps the most exciting aspect of this star is that it must have still failed to explode as a supernova.

These giant explosions are really important in mapping the structure of the universe, because they were detected at great distances. However, there is still a lot of uncertainty about what kind of star systems make it a supernova state.

It may seem strange, since it measures the properties of failed supernovae and the similar future gives us self-thermonuclear. Saying a lot on the road to analysis. The discovery is reported in an article published in a magazine called Nature Astronomy.

Astronomers discovered a white dwarf formed by the merger of two stars. Artist’s rendering of the white dwarf star. An international team of researchers led by the University of Warwick, a scientific member of the IAC, discovered white dwarfs with unusual dimensions. This star may, in fact, be the result of a fusion of two white dwarfs.

This discovery is published today in a magazine called Nature Astronomy, and may answer some questions about the evolution of white dwarfs and about the number of supernovae in our galaxy. The star, located 150 light-years away, was identified by data from the GAIA satellite telescope of the European Space Agency (ESA).

Based on this, astronomers used the William Herschel Telescope (WHT) from the Isaac Newton Group of Telescopes (ING) at the Rook de los Muchachos Observatory (Garfia, La Palma) to observe potential white dwarfs with unusually large dimensions.

He used the spectroscope to analyze the chemical composition of its atmosphere and detect unusually high levels of carbon there. First paper author Mark Holland of the Warwick Physics Department in England commented: “This star stood out because it was different from anything we had seen before.

We generally expect to find an outer layer of hydrogen, times by helium or a combination of carbon and carbon. He doesn’t expect to find hydrogen and carbon together since they must have a thick layer of helium between them to avoid this. When we saw it, it didn’t make sense.

To try to solve the mystery, scientists investigated the origin of the star. White dwarfs are remnants of sun-like stars that have used up all their fuel and ejected their outer layers. Most are light (about 0.6 times the mass of the Sun) but about twice the mass of this white dwarf.

However, the star’s diameter is only two-thirds that of Earth, which is 150 times smaller than the Sun. The age of the white dwarf was another clue that the researchers followed. Older stars move faster in the Milky Way than younger stars.

The object moved faster than 99% of other white dwarfs of the same age, co-author of this article, IAC researcher Paula Izkierdo explains. This suggests that Tara should be older than she seems. We can’t explain its structure.

And connects the Netherlands through normal stellar evolution, has twice the expected mass for a white dwarf, and has a longer kinematic lifespan than a cold. We are sure that since a white dwarf should not behave in this way, the only way to explain it is that it is made up of a fusion of two white dwarfs.

When a star expands in a binary system, towards the end of its life, it can form an envelope around its partner, and the orbit brings them closer together, reducing the first star. The same can happen when the second star extends. Over billions of years, gravitational radiation will reduce orbits, to the point where the two stars merge.

Although the merger of dwarf stars is predicted, this is particularly unusual. Most mergers in our galaxy occur between stars with different masses, while it appears to have occurred between two stars with similar masses. The mass of the resulting white dwarf also has a physical limit.

If it exceeds 1.4 solar masses, we believe it will explode as a supernova, although it is possible that these explosions occur at a lower mass. Therefore, the discovery of this star is useful in showing how heavy a white dwarf can be, and is still alive.

Because the fusion enhances the cooling of the star, it is difficult to determine its age. This white dwarf probably formed from a fusion 1.3 billion years ago, but the original two white dwarfs may have existed billions of years ago.

“Perhaps the most exciting thing about this star, Holland’s conclusion that it did not explode as a supernova, is that giant explosions are very important for mapping the structure of the universe, because they were detected at great distances.

However, there is still a considerable uncertainty about what types of star systems reach the supernova phase. Although it seems strange to measure the properties of a “failed” supernova, and others like it in the future, it tells us a lot about the pathways to thermonuclear self-destruction.

The alchemy of neutron stars. Astronomers find that the collision of these cosmic objects actually produces heavier elements. Astronomy Astrophysics Gravitational waves Particle physics. This was a sensation when astronomers observed gravitational waves from two merged neutron stars and one Kilonova in the optical range on August 17, 2017.

At the time, such cosmic collisions were believed to produce heavier elements such as gold or platinum. Now astronomers, including those at the Max Planck Institute for Astronomy in Heidelberg, have identified one such element in the spectra of the time: strontium.

Which apparently occurred in the so-called R process. This rapid neutron capture appears to be crucial to producing elements that are heavier than iron. Astronomers have now unevenly shown that the merger of two neutron stars creates conditions for this process and acts as a reactor in which new elements are produced.

This artist’s impression shows two small but very dense neutron stars, at which point they merge and explode like a Kilonova. The origins of heavy elements like gold, lead, and uranium have yet to be fully clarified.

With the Big Bang, the lighter elements, hydrogen and helium, had already formed in significant quantities. Atomic fusion in the nucleus of stars is also a well-established source of large-scale atoms, from helium to iron.

For the production of heavy atoms, scientists suspect that there is a process involving free neutrons in existing building blocks. The fastest version of this mechanism is the so-called R process (stands for R fast) or fast neutron capture. Research is currently underway to determine which objects may be sites where this reaction occurs.

The possible candidates so far are a rare type of supernova explosion and a fusion of dense stellar debris like binary neutron stars. Illustration of the process R. Neutrons rapidly form large compounds of which individual neutrons break down into protons, while an electron and an antinutrino are emitted during each individual reaction.

An international group of astronomers with substantial participation from Camilla Juel Henson of the Max Planck Institute for Astronomy (MPIA) in Heidelberg has discovered the signature of the element strontium, which was formed by the R process during the explosive fusion of two neutron stars.

On average, 88 nucleons, of which 38 are protons, are heavier than iron. The explosive fusions produced a furious layer of expansion with 20 to 30% of the speed of light. It contains newly formed substances, of which strontium has only about five land masses.

Therefore, for the first time, researchers provide clear evidence that such collisions provide conditions for the R process in which heavy elements are formed. Also, this is the first empirical confirmation that neutron stars contain neutrons. The R process is really fast. Per second, more than 10 neutrons flow over an area of one square centimeter.

Beta decay converts some accumulated neutrons into protons, emitting an electron and an antinutrino. The special aspect of this mechanism is that neutrons come together and decompose faster to form larger compounds than the newly formed group. In this way, the heaviest elements can grow from individual neutrons in less than once.

Using the Very Large Telescope (VLT) from the European Southern Observatory (ESO), the scientists obtained the spectra in August 2017 after a surprising discovery of the gravitational wave signal GW170817. In addition to a gamma ray burst, Kilonova AT2017gfo, Afterglow.

Visible light due to radioactive processes, which faded a few days after the initial sharp increase in brightness, occurred at the same location. The first spectrum analysis in 2017 by another group of researchers did not give a clear result on the composition of the reaction products.

Hansen and colleagues did their reevaluation by creating synthetic spectra and modeling the observed spectra, which were recorded at intervals of one day each for four days. The spectra indicate an object with an initial temperature of approximately 3400 ° C, which faded and cooled over the following days. Brightness is reduced at wavelengths of 350 and 850nm.

Considering the blue shift of these absorption lines due to expansion after fusion events due to the Doppler effect, the research group calculated the spectra of a large number of atoms using three increasingly complex methods. Since all of these methods produce consistent results, the bottom line is solid.

It was discovered that only the strontium spectra generated by the R process can explain the position and strength of the absorption characteristics. The results of this work are an important step in defining the nucleosynthesis of heavy elements and their cosmic sources, concludes Hanson.

This was possible only by combining the new discipline of gravitational wave astronomy with the precise spectroscopy of electromagnetic radiation. These new methods offer hope for new innovative ideas about the nature of the R process.

Pulsed white dwarf in a binary star system. This star can answer what will happen to our sun in the future. While studying a system with two white dwarfs, astronomers made a surprising discovery: one of the objects is pulsed. Throughout its life, our Sun will go through various stages of stellar evolution, and will eventually end its life as a white dwarf.

Now, based on a new discovery by researchers at the University of Sheffield, we may be able to unlock even more information about the fate of our Sun. Pulse to Beat: Astronomers studying the white dwarf binary system have found a new pulsed white dwarf.

We had no idea the white dwarf was pulsed when we started working, said the paper’s first author, Steven Parsons of Sheffield, in an email to Astronomy. It was a small part of fate that allowed us to discover the vibrations.

Fate came in the form of data from Hypercamer, a high-speed imaging camera on top of the Gran Telescopio Canarias, the world’s largest telescope. The camera is capable of taking a photo in five different colors every millisecond.

That ability has allowed a graduate student to work with data that one of the white dwarfs in the system is rapidly pulsing. “Much of the work for this job was done by a graduate student,” Parsons said.

Those vibrations will now help astronomers learn how the binary star system affects the internal structure of the white dwarf, which in turn will teach us more about these strange star remains. This binary system is even more special.

Two stars are also eclipsing, meaning they pass in front of each other as seen from Earth. The white dwarf is the first pulsed star of its kind found in such a star system. Through vibrations and eclipses, the team measured the mass and radius of the white dwarf and that allowed them to determine what it was made of.

It is generally very difficult to determine what causes a white dwarf because it is hidden underneath the surface layer of all the hydrogen that we cannot see,” Parsons said. “However, the shape of a white dwarf is influenced by its internal structureMost white dwarfs are made of carbon and oxygen.

When a star runs out of hydrogen and begins to convert helium into heavier elements. But it is made of helium. The team believes it to be a strange creation because the star’s companion quickly stopped its development, leaving it with this strange chemical composition before helium could fuse.

The team’s work was published in the March 16 Nature Astronomy. Now, the researchers plan to continue observing the white dwarf to record as many vibrations as possible using HiPERCAM and the Hubble Space Telescope.

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