Cymek said:
mollwollfumble said:
Tau.Neutrino said:
Pulsations detected in a hot, helium-atmosphere white dwarf
(Phys.org)—Astronomers have recently discovered non-radial oscillations in a hot, helium-atmosphere white dwarf designated PG 0112+104. The newly detected 11 independent pulsation modes in this white dwarf could be essential for researchers testing the radial differential rotation and internal compositional stratification of highly evolved stellar remnants. The findings were presented in a paper published Dec. 22 on the arXiv pre-print server.
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There are two types of pulsations. Pulsations of variable stars and pulsations of normal stars. The white dwarfs that are variable stars are known as ZZ dwarfs, they lie in the instability strip along with many other types of variable stars.
I’m not sure yet whether this is a ZZ dwarf or not.
Would be quite top if it was the ZZ type
More exciting if it wasn’t a ZZ dwarf. Then we could have the first example of “weather” on the surface of a white dwarf star.
“The relatively low-amplitude pulsations observed in PG 0112+104 demonstrate that many white dwarfs that have been observed not to pulsate, mostly from the ground, may indeed vary but at amplitudes below historical detection limits”, suggests not ZZ dwarf.
But on the other hand “non-radial” means nothing. Because the pulsations of most variable white dwarfs are non-radial, according to https://en.wikipedia.org/wiki/Pulsating_white_dwarf
Although the Wikipedia article on pulsating white dwarf concentrates on the composition of the atmosphere (H, He or C), the atmosphere is so thin that IMHO its influence on variability ought to be small or even negligible.