At the heart of every white dwarf star – the dense stellar object that remains after a star has burned up its fuel reserve as it nears the end of its life cycle – lies a quantum summary: as white dwarfs add mass, they they shrink in size, until they become so small and tightly packed that they can no longer hold themselves, collapsing into a neutron star.
This dizzying relationship between a mass and the size of the white dwarf, called the mass-ray relationship, was first theorized by Nobel ion-winning astrophysicist Chandrasekhar in the 1930s. Now, a team of astrophysicists Johns Hopkins has developed a method to observe the phenomenon itself using astronomical data collected by the Sloan Digital Sky Survey and a recent database released by the Gaia Space Observatory. The combined data provided more than 3,000 white dwarfs for the team to study.
A report of their findings, led by elderly Hopkins Vedant Chandra, is now in print Astrophysical Magazine and available online at arXiv.
“The mass-beam connection is a spectacular combination of quantum mechanics and gravity, but it is counterintuitive to us – we think that as an object gains mass, it should become larger,” says Nadia Zakamska, associate professor in the Department of Physics and Astronomy that supervised student researchers. “The theory has been around for a long time, but what stands out is that the data set we used is of unprecedented size and unprecedented accuracy. These measurement methods, which in some cases were developed years ago , all of a much better unexpected work, and these old theories can finally be proved. “
The team obtained their results using a combination of measurements, including mainly the reddish gravitational effect, which is the change in light wavelengths from blue to red as light moves away from an object. It is a direct result of Einstein’s theory of general relativity.
“For me, the beauty of this work is that we all learn these theories of how light will be affected by gravity in school and in textbooks, but now we actually see that relationship in the stars themselves,” says the graduate student. fifth year Hsiang -Chih Hwang, who proposed the study and recognized for the first time the gravitational effect of reduction in data.
The team also had to account for how the movement of a star through space could affect the perception of its gravitational repurchase. Similar to how a fire engine siren changes pitch, according to its motion relative to the hearing person, light frequencies also change depending on the motion of the object emitting light in relation to the observer. This is called the Doppler effect, and is essentially an attractive “noise” that complicates measuring the gravitational effect of reduction, says study contributor Sihao Cheng, a fourth-year graduate student.
To calculate the changes caused by the Doppler effect, the team classified the white dwarfs in their radially placed sample. They then averaged star sequences of a similar size, effectively determining that regardless of where a star is located on its own or where it is moving relative to Earth, one can expect an internal gravitational repurchase of a value of assigned. Think about how taking an average measurement of all the lands of all the fire engines moving in a certain area at a given time – you can expect that every fire engine, no matter in which direction it is moving, will have an internal step of that average value.
These internal variable values of gravity can be used to study the stars that have been observed in future data sets. The researchers say that future data that are larger and more accurate will allow further adjustment of their measurements, and that these data may contribute to future analysis of the chemical composition of white dwarf.
They also say that their study represents an exciting breakthrough from theory to observed phenomena.
“Because the star gets smaller as it gets more massive, the red gravitational effect also increases massively,” says Zakamska. “And it’s a little easier to understand – it’s easier to get out of a less dense, bigger object than to get out of a more massive, more compact object. And that’s exactly what we saw in data “.
The team is even finding captive audiences for their home research — where they conducted their work amid the coronavirus pandemic.
“The way I laid it out to my grandfather, you are basically looking at quantum mechanics and Einstein’s theory of general relativity to come together to bring this result,” says Chandra. “He was very excited when I put him that way.”
Astrophysicists confirm the cornerstone of Einstein’s Theory of Relativity
A Gravitational Redshift Measurement of the Mass-Radius Relationship of the White Dwarf, arXiv: 2007.14517 [astro-ph.SR] arxiv.org/abs/2007.14517
Provided by Johns Hopkins University
citation: Astrophysicists observe long theorized quantum phenomena (2020, July 30) taken on July 30, 2020 from https://phys.org/news/2020-07-astrophysicists-long-theorized-quantum-phenomena.html
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