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Insights Into the WD1032+011 Binary System Revealed by Hubble Observations
A recent observational campaign led by astronomers using the Hubble Space Telescope (HST) has shed new light on the binary system WD1032+011, which consists of a white dwarf and a brown dwarf. The results of this study, published on September 10 on the arXiv preprint server, provide valuable insights into the characteristics and behavior of this intriguing astronomical system.
White dwarf-brown dwarf binaries are a relatively rare phenomenon in the universe. In such systems, brown dwarfs must successfully avoid being consumed by the progenitor of the white dwarf. Although extensive all-sky surveys have identified thousands of white dwarfs, only a tiny fraction—approximately 0.1% to 0.5%—is believed to have brown dwarf companions.
WD1032+011 stands out as an eclipsing, tidally-locked binary system with an orbital period of 0.09 days and an inclination angle of 87.5 degrees. The separation between the two celestial bodies is around 0.003 AU, with the white dwarf (designated WD1032+011A) and the brown dwarf (WD1032+011B) having estimated masses of 0.45 and 0.066 solar masses, respectively.
Led by Jenni R. French from the University of Leicester, the research team employed HST’s Wide Field Camera 3 (WFC3) to gather detailed spectrophotometric data of WD1032+011. “Our study reveals Hubble Space Telescope Wide Field Camera 3 time-resolved spectrophotometry of the eclipsing white dwarf–brown dwarf binary WD1032+011. The resulting broadband light curve captures the primary eclipse, during which the brown dwarf completely covers the white dwarf,” the researchers noted in their findings.
The data collected indicated that the brown dwarf, WD1032+011B, possesses dayside and nightside temperatures of approximately 1,748 K and 1,555 K, respectively. Furthermore, the spectral classification indicates it is likely an L1 peculiar type, suggesting features indicative of a cloud-free atmosphere.
Notably, the study reveals that WD1032+011B has a radius of about 0.1 solar radii, suggesting that it is inflated—a phenomenon attributed to heating from the nearby white dwarf. This characteristic makes WD1032+011B a unique example of an inflated brown dwarf within an eclipsing white dwarf-brown dwarf binary system.
On the other hand, the white dwarf WD1032+011A has a radius of approximately 0.015 solar radii and an effective temperature of around 9,950 K. Estimates indicate that the WD1032+011 system lies roughly 1,020 light years from Earth and is at least five billion years old.
According to the authors, the observed properties of WD1032+011 may categorize it as a cataclysmic variable, although no magnetic signatures have been detected in the spectrum of the white dwarf, which would provide further evidence supporting this classification.
More information: Jenni R. French et al, The only inflated brown dwarf in an eclipsing white dwarf-brown dwarf binary: WD1032+011B, arXiv (2024). DOI: 10.48550/arxiv.2409.06874
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phys.org