Astrophysicists observe long-term quantum phenomena

The central star of the Planetary Nebula NGC 2440, HD 62166, is possibly the most famous white dwarf star ever discovered. White dwarfs exhibit quantum phenomena: as they gain mass, they shrink in size. Sincerely: PIXABAY

At the heart of every white dwarf star – the dense stellar object that remains after one star burns the fuel of gases as it reaches the end of its life cycle – a quantum conundrum is contained: white dwarfs form the mass In, they shrink in size, collapsing into a neutron star until they are so small and tightly compressed that they cannot sustain themselves.

The widespread relationship between the white dwarf’s mass and size, called the mass-radius relationship, was first classified in the 1930s by Nobel Prize-winning astrophysicist Subrahmanyan Chandrasekhar. Now, a team of Johns Hopkins astronomers has developed a method to observe the phenomenon using astronomical data collected by the Sloan Digital Sky Survey and a dataset recently released by the Gaia Space Observatory. The combined dataset provided the team with over 3,000 white dwarfs to conduct the study.

A report of his findings led by Hopkins senior Vedanta Chandra is now in press Astrophysical Journal And is available online at arXiv.

Nadia Zamska, an associate professor in the physics department and says, “The mass-radius relationship is a brilliant combination of quantum mechanics and gravity, but it is very important to us. Astronomy that supervised student researchers.” Theory has long been Does exist, but it is notable that the dataset we have used is of unprecedented size and unprecedented accuracy. These measurement methods, which were developed a few years ago, suddenly work so well and all these old theories can finally be tested. “

The team obtained their results using a combination of measurements, which mainly involves the gravitational redshift effect, which is the change of wavelength of light from blue to red when moving away from an object. This is a direct result of Einstein’s theory of general relativity.

“The beauty of my work is that we all learn these theories about how light will be affected by gravity in school and in textbooks, but now we really see that relationship in the stars themselves,” a fifth-year graduate student Hsiang says -Chih Hwang, who proposed the study and first recognized the gravitational redshift effect in the data.

The team also had to keep in mind how the movement of a star through space could affect the perception of its gravity redistribution. Similar to how a fire engine siren changes pitch according to its movement in relation to the person listening, the light frequencies also change depending on the movement of the light-emitting object with respect to the observer. The study is called the Doppler effect, and is essentially a distracting “noise” that complicates the measurement of the gravitational rebalance effect, says study contributor Sihao Cheng, a fourth-year undergraduate student.

For variations caused by the Doppler effect, the team classified the white dwarfs in their sample as determined by Radius. They then averaged the redshift of uniformly sized stars, effectively determining whether any star where itself is located or where it is rotating with respect to the Earth has an intrinsic gravity of a certain value. Redevelopment can be expected. Think about taking an average measurement of all the pitches of all fire engines moving around in a given area at any given time — you can expect that any fire engine, regardless of the direction it is moving, averages that The internal pitch will be the value.

These intrinsic gravitational riftft values ​​can be used to study stars seen in future datasets. Researchers say the upcoming datasets are larger and more accurate, which will allow their measurements to be further corrected, and this data may contribute to future analysis of white dwarf chemical composition.

They also say that their study represents an exciting advance from theory to observed phenomena.

“Because the star becomes more small as it becomes more massive, the gravitational redshift effect also increases with mass,” says Zakmska. “And it’s a little easier to understand – it’s easier to get out of a less dense, bigger object out of it than a larger, more compact object. And that’s exactly what we’ve seen in the data.”

The team is also looking for captive audiences for their research at home – where they have done their job amid the coronovirus epidemic.

“The way I passed it on to my grandfather, you’re basically looking at quantum mechanics and Einstein’s theory of general relativity,” says Chandra. “He was very excited when I planted him like this.”

Astrophysicists confirm the cornerstone of Einstein’s Theory of Relativity

more information:
A gravimetric measurement of white dwarf mass-radius relation, arXiv: 2007.14517 [astro-ph.SR]

Provided by Johns Hopkins University

Quotes: Astrophysicists observe long-term quantum events (2020, 30 July), from 30 July 2020.

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