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Updated: Jul 23, 2025
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
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A rotating white dwarf shows different compositions on its opposite faces.
Ilaria Caiazzo1, Kevin B Burdge2,3, Pier-Emmanuel Tremblay4
1Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA, USA. ilariac@caltech.edu.
Nature
|July 19, 2023
Summary
Astronomers discovered a unique white dwarf star, ZTF J203349.8+322901.1, with one side of its atmosphere made of hydrogen and the other of helium. This "two-faced" star offers new insights into stellar evolution and the impact of magnetic fields on white dwarfs.
Area of Science:
- Stellar Astrophysics
- White Dwarf Evolution
- Planetary Science
Background:
- White dwarfs are dense stellar remnants with Sun-like mass and Earth-like size.
- Gravitational settling causes heavy elements to sink, leaving light elements like hydrogen or helium in the atmosphere.
- White dwarf atmospheres transition from hydrogen to helium dominated as they cool below 30,000 Kelvin.
Purpose of the Study:
- To report the discovery and observation of a unique transitioning white dwarf, ZTF J203349.8+322901.1.
- To investigate the cause of its peculiar two-faced atmospheric composition (hydrogen and helium).
- To explore the role of magnetic fields in white dwarf spectral evolution.
Main Methods:
- Observational astronomy utilizing advanced telescopes to capture spectral data.
- Analysis of atmospheric composition and temperature variations across the white dwarf's surface.
- Comparison with existing models of white dwarf cooling and magnetic field effects.
Main Results:
- Discovery of ZTF J203349.8+322901.1, a white dwarf with distinct hydrogen and helium-dominated atmospheric regions.
- The observed inhomogeneity is likely caused by a weak magnetic field influencing surface conditions.
- This finding suggests ZTF J203349.8+322901.1 is an extreme example of a class of magnetic, transitioning white dwarfs.
Conclusions:
- The existence of ZTF J203349.8+322901.1 provides strong evidence for magnetic fields influencing white dwarf atmospheric composition.
- This discovery aids in understanding the spectral evolution of white dwarfs.
- Further study of this class of magnetic white dwarfs can illuminate fundamental stellar processes.
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