Sur cette vue d’artiste, une naine blanche en train de se nourrir de la matière arrachée à son étoile compagne. © Helena Uthas, Université de Durham

This white dwarf died suddenly

A white dwarf is what remains of a star when it “burns” all the hydrogen. Astronomers just noticed that one of these white dwarfs turns off and then turns back on in just 30 minutes. It is the first time that such a phenomenon has been detected in such a short time.

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a white dwarfHe is a star at the end of his life. The fate that awaits most stars when they burn with them hydrogen. They end up collapsing to reduce a size similar to the size of the Earth while they exist Mass Still similar to Soleil. Some white dwarfs feed on Thing They extract from a companion star. they brightness It can then vary over time from a few days to a few months.

but Durham University researchers (UK) today reported that it noticed a white dwarf That lost its luster in just 30 minutes. before you restore it! A unique phenomenon detected by the TESS satellite (Transiting Exoplanet Survey) Its main objective is expulsion of the outer planets. A phenomenon, too, that cannot be fully explained according to scientists’ understanding, to this day, of the way these systems feed.

This white dwarf is TW Pictoris, a star constellation Painter, visible inSouthern Hemisphere. Fall on at least 1400 light years from our land. TW Picoris is exactly the name star system Who is the white dwarf in question. This, therefore, feeds on a Accumulation disk Equipped with hydrogen and helium by star companion Thus, in principle, it becomes brighter.

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Better understanding of the phenomenon of accumulation

However, observations by researchers at Durham University show a sharp decrease and increase in brightness on very short time scales. This phenomenon is even more surprising Astronomy scientists The flow of matter in the accretion disk appears to be relatively constant.

The hypothesis put forward by researchers to explain these mood swings is that magnetic field On the surface of a white dwarf, it can undergo a series of remodeling processes. what they call fashion ” on fire “, which corresponds to a high luminosity, the white dwarf feeds on the surrounding matter. And suddenly, the system turns off and the brightness collapses. Possibly due to a magnetic field rotating so rapidly that some kind of centrifugal barrier prevents the material from accumulating.

Thus, astronomers invoke the existence of a kind of « Door magnetic” It is through them that the nutrition of the white dwarf is regulated. Resulting in the small, semi-regular increases in brightness that they also observed. After a while, the system will turn on intermittently and the brightness will return to its original level.

More broadly, astronomers hope their discovery will shed light onphysique Which is still hidden behind the accretion phenomenon that is observed not only on white dwarfs, but also black holes and neutron stars. It may shed light on the important role played by magnetic fields.

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