Thinking Hard About \u27Race-Neutral\u27 Admissions

Our exploration is organized as follows. In Part I, we sympathetically consider the very difficult dilemmas facing higher education leaders. Understanding the often irreconcilable pressures that constrain university administrators is essential if we are to envision the plausible policies they might undertake. In Part II, we draw on a range of data to illustrate some of the “properties” of admissions systems and, in particular, the ways in which race, SES, and academic preparation interact dynamically both within individual schools and across the educational spectrum. Partly because the questions we examine here have been so little studied, ideal data does not exist, but there are enough government and university sources of data to grasp many key dynamics. In Part III, we turn to the “compliance” question—how have major schools conformed with or evaded the requirement of race-neutral policies? We examine in some depth admissions data from the University of California and the University of Michigan and find strong evidence of non-compliance in both cases. What does their conduct tell us about the operation of these policies? In Part IV, we detail a tentative policy agenda that follows from our findings

On the binary nature of massive blue hypergiants: high-resolution X-ray spectroscopy suggests that Cyg OB2 12 is a colliding wind binary

The blue hypergiant Cyg OB2-12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism de-populating the metastable upper levels of the forbidden lines of the He-like ions SiXIV and MgXII. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2-12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-rays sources. We suggest that our new Chandra observations of Cyg OB2-12 can be best explained if Cyg OB2-12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2-12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companion.Comment: accepted to Ap