Rotation and Luminosity Budgets of a Blue Straggler Formed by a 1.2 plus 0.8 Solar-Mass Main-Sequence Merger

This paper examines the merger of main-sequence stars of 1.2 and 0.8 solar masses in contact, producing a blue straggler of about 1.92 solar masses and 1.45 solar radii after modest mass loss. Using published input values and the standard energy comparison between envelope binding and orbital release, the calculation addresses the specific budget that decides the outcome for this pairing. The headline results are: omega_fraction_of_breakup = 3.929; spin_period_if_all_retained_min = 53.50; breakup_period_min = 210.18. The method, inputs and limitations are stated in full so that any reader can reproduce or rescale every number from the deposited calculation script. A main-sequence merger is an envelope event without an envelope: two whole stars become one, and the questions are where the orbital angular momentum goes and how luminous the product can be. Agreement and disagreement with published values for this class are reported at their actual size, and the conclusions are limited to what the budget arithmetic supports.