What the spectrum says directly
JWST's NIRSpec saw MoM-BH*-1 at redshift 7.7569; we are looking at light from 660 million years after the Big Bang. Between 3 and 4 micrometres the flux falls by more than 20-fold. Broad Hβ emission arrives with Hβ and Hγ absorption. Those are instrument measurements; the name ‘black-hole star’ comes from the physical model built to explain them.[1]
The measured Balmer-break strength is 7.7; even an extreme stellar-population calculation stays below 5. The unresolved source is smaller than 117 parsecs. The team reproduced the spectrum's main features with a black hole radiating inside very dense, turbulent gas. Their caution is decisive: the gas geometry and the central source's spectrum remain uncertain, and the chosen model is a simple example within a wide field of possibilities.[1]
The light line bends the ruler
The same gas makes the black hole harder to weigh. A local Hβ relation that assumes no dust gives about 50 million solar masses. If scattering in the gas inflates the line width, a calculation using an intrinsic width of 600 km per second falls to about 1 million solar masses. This spread of about 2 orders of magnitude comes from the model chosen between measurement and mass, rather than a change in the black hole.[1]
An independent spectrum with a higher signal-to-noise ratio and a repeat brightness measurement in the same instrument offer two suitable tests. Existing data point to 30 per cent brightening, with 7 per cent uncertainty, over 60 rest-frame days, but the observations used different modes; calibration remains a strong rival explanation. Uncertainty is no measure of our smallness when we look into the distant universe. New light matters here because it can test which ruler is sound.[1]