δ²⁶Mg* DEFINED

'A perspective from extinct radionuclides on a Young Stellar Object: The Sun and its accretion disk', Dauphas and Chaussidon,
Annual Review of Earth and Planetary Sciences, vol. 39, pp. 351–386 (2011)
(https://doi.org/10.1146/annurev-earth-040610-133428) (https://arxiv.org/ftp/arxiv/papers/1105/1105.5172.pdf)

--------excerpt from p. 7--------

... where δ²⁶Mg* is the radiogenic excess in the ²⁶Mg/²⁴Mg ratio in parts per thousand, defined as δ²⁶Mg* =
[(²⁶Mg/²⁴Mg)_sample/(²⁶Mg/²⁴Mg)_CHUR – 1] × 10³

{CHUR = chondritic uniform reservoir}

δ²⁶Mg* values should increase proportionally to the decrease of their ²⁶Al/²⁷Al ratios:

~0.03‰ increase of the δ²⁶Mg* value for complete ²⁶Al decay; i.e., from ²⁶Al/²⁷Al = 5.2 × 10^–5 to 0