GLIMPSE-17775 spectrum

The NASA/ESA/CSA James Webb Space Telescope’s spectroscopic data on little red dot GLIMPSE-17775 contains more than 40 spectral lines. The spectrum contains multiple independent indicators that support the theory that this little red dot is a black hole star: a rapidly accreting, or growing, black hole enveloped in a hot, dense gas cocoon. This layered, shell-like environment is reprocessing the light emitted from near the black hole and producing the features seen in the spectrum.

For example, scientists found that many of the spectral lines, such as hydrogen, oxygen, and helium, do not match a simple, rotating gas cloud model. The best fit model includes a broadening effect known as electron scattering, a telltale sign that a dense, layered gas cocoon is enshrouding the source.

[Image description: A spectrum graphic showing the amount of light blocked on the y-axis versus wavelength of light, in microns. The bottom of the y-axis is labeled “fainter,” and the top is labeled “brighter.” The x-axis starts with 2.80 microns at left and continues in increments of five, ending with 3.05 microns at right. A key at top left has a white line labeled “Data” and a small blue square labeled “Model of light scattered through hot dense gas.” The white data line is stepped with a large bell-like curve that peaks at 2.95 microns. It is labeled “hydrogen” and highlighted by a semi-transparent purple. The data also forms small peaks highlighted with different colors: around 2.84 microns, oxygen, green; 3.0 microns, helium, red; and 3.02 microns, sulfur, orange. The blue filling, representing the model, approximately fills the bell-like curve that marks hydrogen. A smaller peak of blue also approximately fills the data’s peak of helium.]