Stellamoti: The smallest discovery ever recorded

An artistic representation of pressure waves, of different frequencies, propagating in the inner layers of a star. Credits: Tania Cunha (Planetário do Porto – Centro Ciência Viva)/Instituto Astrofísica e Ciências do Spaço

Inside stars, the turbulent movements of matter generate pressure waves that make their surfaces pulsate. stellamutti, Earthquakes In English, this is what these waves capable of shaking stars are called. Just as geologists use earthquakes to study the Earth's structure, astronomers use stellar quakes to obtain information about the structure and internal composition of stars. Using technologies AstroseismologyThe science that studies these phenomena, Thiago CampanteastronomerInstitute of Astrophysics and Space SciencesHis colleagues have now been able to detect very small pulses on the surface of one of them Orange dwarfThe star Epsilon Indians, is attributed to the smallest stellamoto ever discovered. In the studioAccepted for publication in Astronomy and Astrophysics LettersEnrico Corsaro and Ennio Burretti from Enav participated.

One way to detect star movements involves measuring small variations in starlight. In fact, the celestial body's surface pulsations affect the wavelengths of visible radiation we observe, resulting in blue or red shifts Doppler effectcan be detected by measurement Radial velocity From the star. In the study in question, using spectroscopy espresso mounted on Very large telescope ESO researchers were able to record these luminous differences in the spectrum of Epsilon Indi, an orange dwarf 11.9 light-years away from Earth, located in the Indian constellation.

“Radial velocities are a measurement obtained thanks to the Doppler effect produced by the star's oscillations on its spectrum.” Enaf media Enrico pirate, an astronomer at INAF in Catania and co-author of the publication. “When these oscillations (or stellar movements) occur – Corsaro adds – the star expands and contracts continuously. When it expands, due to the Doppler effect, the lines of the spectrum shift towards blue, and vice versa, when it contracts, the lines move towards red. Thanks to instruments such as spectrometers, we are able to observe these differences, even if they are of very small magnitude, which are directly related to the fundamental properties of the star such as mass and radius, and to its internal structure.

A diagram showing some properties of the orange dwarf Epsilon Indi and the Sun in comparison. Credits: Paulo Pereira (Institute of Astrophysics and Science do Spaso)

Subsequent translation of these light differences into sound waves allowed the researchers to observe something they had not expected. In the resulting frequency spectra, they found that the amplitude of the waves varied by a few centimeters per second (a value of about 14% of the amplitude of the waves' oscillation). Earthquakes Recorded on Our Star): The youngest Stellamoto signature recorded to date.

The extreme level of precision of these observations demonstrates that it is possible to perform astroseismology even on stars with surface temperatures of up to 4,200 degrees Celsius, about 1,000 degrees lower than the surface temperature of the Sun, effectively opening up a new field, the researchers explain. In observational astrophysics.

“Thanks to the capabilities of the Espresso spectrometer, we were able to capture oscillations on the surface of the star with an amplitude of only 2.6 cm per second,” Corsaro confirms. “This new resolution limit allows us to measure oscillations in a new and previously inaccessible system, a system of cold K-type stars with temperatures of about 4,200 degrees Celsius, which present very small oscillations. Before this work, the star was The coldest star in which Sun-like oscillations have been measured Kepler-444Which has a temperature of more than 4700 degrees Celsius.”

The results obtained in this study may help scientists resolve the long-standing dispute between theory and observations about the relationship between the mass of these stars and their diameter. Spectral class k e Brightness class Fifth.

Enrico Corsaro, a researcher at INAF in Catania, is co-author of the study accepted for publication in A&AL

“It is known that models of stellar evolution underestimate the diameter of K dwarfs by 5-15 percent compared to the value obtained by experimental methods,” he says in this regard. Margarida CunhaResearcherInstitute of Astrophysics and Space Sciences And co-author of the publication. “Studying the oscillations of K dwarfs through astroseismology will help identify the shortcomings of current stellar models and thus improve them in order to eliminate this discrepancy.”

Orange dwarves and theirs Planetary systems It has recently become a primary target in the search for habitable worlds and extraterrestrial life. The researchers point out that the results of this study prove that astroseismology can now be used for the detailed characterization of these stars and their habitable planets. Furthermore, accurately determining the age of nearby cool stars using astroseismology can be crucial for interpreting biofirme Of the exoplanets that have been imaged across Live photography.

After discovering the existence of solar-type oscillations in Epsilon Indi, what researchers now plan is to use the oscillations to study the complex physics of K-type dwarf stars. These stars are actually cooler and more active than our Sun, which makes them veritable laboratories for probing fundamental phenomena that occur in their layers. Surface, which has not yet been studied in detail.

The researchers concluded that every time we open a new window on nature, new surprises lead us to unexpected discoveries. Epsilon Indi promises to be one such window. Window with bright view.

to know more:

• Read on Astronomy and Astrophysics Letters Article “Expanding the boundaries of cold dwarf stellar seismology with ESPRESSO. Detecting solar-like oscillations in the K5 dwarf H dew“, di TL Campante, H. Kjeldsen, Y. Li, MN Lund, AM Silva, E. Corsaro, J. Gomes da Silva, JHC Martins, V. Adibekyan, T. Azevedo Silva, TR Bedding, D. Bossini, DL Buzasi, W. G. Chaplin, R. R. Costa, M. S. Cunha, E. Cristo, J. B. Faria, R. A. Garcia, D. Huber, M. S. Lundqvist, T. S. Metcalfe, M. J. B. F. G. Montero, A. W. Neitzel, M. B. Nielsen. ,E. Burretti, N.C. Santos, and S.J. Souza