In a major development that could change scientists’ understanding of the universe, the sun, the star at the center of our solar system, may not be as big as we think. According to a report by science alertTwo astronomers have found evidence that the sun’s radius is several hundredths of a percent narrower than previous analyzes showed.
The new discovery, currently under peer review, is based on sound waves generated and trapped inside the Sun’s hot plasma, known as “pressure” or p-modes.Papers that explain these in detail The findings were published on arXiv.
Astrophysicists Masao Takada from the University of Tokyo and Douglas Goff from the University of Cambridge explained that p-mode oscillations provide a “dynamically more robust” view of the Sun’s interior compared to other oscillating sound waves. To understand this better, you can imagine that the sun is like a bell ringing as it is struck by tiny grains of sand. That ground motion generates millions of vibrational sound waves, including p-waves, g-modes, and f-modes.
F-mode is the mode traditionally used to measure the seismic radius of the Sun. However, scientists have discovered that they are not completely reliable because they do not extend to the edge of the sun’s photosphere. Rather, p-mode is more useful because it reaches farther and is less affected by magnetic fields and turbulence in the upper boundary layer of the Sun’s convective zone.
“Analysis of f-mode frequencies yields measurements of the Sun’s radius that are several hundredths of a percent smaller than the radius of the photosphere determined by direct optical measurements,” the paper’s introduction says. has been written. Part of this difference lies in the realization that it is primarily density variations well below the star’s photosphere, rather than aspects of radiant intensity, that determine the structure of these essentially adiabatic vibrational modes. You can understand it. ”
Both scientists now argue that p-mode should be used to measure the radius of the sun. Their calculations using only p-mode frequencies suggest that the Sun’s photosphere radius is very slightly smaller than in standard solar models.
In this paper, we attempt to shed further light on this issue by considering an alternatively defined and dynamically more robust seismic radius, namely one determined from the p-mode frequency. This radius is calibrated by the distance from the center of the Sun to the location in the subphotospheric layer where the first derivative of the density scale height varies essentially discontinuously. We see that its radius is more or less consistent with that suggested by the f mode.
Additionally, the interpretation of the radius inferred from the p-modes allows for a deeper understanding of the role of the total mass constraint in structural inversion. “This allows us to reinterpret the sonic reversal and suggests that the location of the photosphere and adiabatic stratification within the convective envelope differs non-homologously from that of the standard solar model,” the study said. ing.