AWhat changed
Sahu and colleagues used Hubble observations of the apparent positional shift of a background star as the nearby white dwarf Stein 2051 B passed in front of it. Fitting the astrometric microlensing model and parallax gave a lens mass of 0.675 ± 0.051 solar masses, providing a comparison point for white-dwarf mass–radius models.
Scientific scope
Sahu and colleagues used Hubble observations of the apparent positional shift of a background star as the nearby white dwarf Stein 2051 B passed in front of it. Fitting the astrometric microlensing model and parallax gave a lens mass of 0.675 ± 0.051 solar masses, providing a comparison point for white-dwarf mass–radius models. The lensing mass uses general relativity and modeled source/lens motion and distances; this is not an independent measurement of the relativistic deflection coefficient or a proof of every white-dwarf mass–radius relation. Of eight observing epochs, only four entered the deflection fit because glare and diffraction compromised source measurements close to the white dwarf. Point-spread-function subtraction and the astrometric reference frame contribute uncertainty. The radius comparison uses photometry and a helium-atmosphere model. The supplementary text prints 52 pc where the main text gives 5.52 pc and the quoted 181 mas parallax implies approximately 5.52 pc; this apparent typo is retained for review. The astrometric result relies on the authors’ image reduction; independent reanalysis would be needed to test it.
Evidence
The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The lensing mass uses general relativity and modeled source/lens motion and distances; this is not an independent measurement of the relativistic deflection coefficient or a proof of every white-dwarf mass–radius relation. Of eight observing epochs, only four entered the deflection fit because glare and diffraction compromised source measurements close to the white dwarf. Point-spread-function subtraction and the astrometric reference frame contribute uncertainty. The radius comparison uses photometry and a helium-atmosphere model. The supplementary text prints 52 pc where the main text gives 5.52 pc and the quoted 181 mas parallax implies approximately 5.52 pc; this apparent typo is retained for review. The astrometric result relies on the authors’ image reduction; independent reanalysis would be needed to test it.
Contributors
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