84 overlooked hypersoft X-ray sources emerge in six nearby galaxies

84 X-ray sources identified in archived observations

ScienceAlert reports that researchers examined observations from NASA's Chandra X-ray Observatory and identified 84 hypersoft X-ray sources, with 7 to 21 found in each of six galaxies including Andromeda and M101. “Hypersoft” refers to sources whose detectable X-rays are relatively low energy; the report says most of their output may instead be extreme ultraviolet light, which interstellar gas absorbs.

Some sources also appeared in XMM-Newton observations, according to the article.

These sources had not been recognized as a distinct astronomical population in earlier Chandra observations.

A reported study has grouped 84 previously overlooked signals across six nearby galaxies as hypersoft X-ray sources, an apparently distinct population visible only through a faint low-energy X-ray tail.

The sources are not all destined to become supernovae

The reported population may be much larger than the 84 detected objects because Chandra has limited sensitivity at these energies. The sources could encompass different systems, including gas-accreting white dwarfs, neutron stars, or black holes. If some are accreting white dwarfs, they could help investigate the still-unresolved lack of observed precursors to Type Ia supernovae.

This does not mean all 84 sources will explode.