Astronomers have discovered four ‘invisible’ stars near the Sun
One might think that the Sun’s immediate surroundings have been studied inside out. However, astronomers have unexpectedly discovered no fewer than four ‘invisible’ stars that have been hiding right under our noses for decades.
They all turned out to be white dwarfs — the extremely dense remnants of stars that once existed. Their light was completely obscured by their brighter neighbours, which is why they have only now been spotted.
The study has been published in the journal *Monthly Notices of the Royal Astronomical Society*.
Why nobody had noticed them
Each of the discovered stars is part of a binary system.
Next to each white dwarf is a red dwarf — a small but brighter star. Its light was so dominant that the white dwarf was literally ‘lost’ against the background of its neighbour when observed in the visible spectrum.
Although astronomers had long suspected the presence of hidden objects based on the slight ‘wobble’ of the red dwarfs caused by gravity, it has only now been possible to directly confirm their existence.
How the ‘invisible’ stars were found
The researchers used the Hubble Space Telescope’s ultraviolet spectrograph.
In the ultraviolet spectrum, white dwarfs are noticeably brighter than in ordinary visible light. After special data processing, the scientists were able to isolate their radiation and confirm the existence of four objects at once.
One white dwarf turned out to be very close by
The G 203-47 system, located just 25 light-years from Earth, was particularly surprising.
Although astronomers had noticed unusual movements of this star as long as 27 years ago, it has only now been possible to detect the hidden white dwarf.
Following this discovery, it has become the ninth closest white dwarf to the Sun of all those known.
Why this is important
White dwarfs represent the final stage in the life cycle of stars similar to our Sun. When such stars exhaust their fuel supplies, they shed their outer layers, and their core transforms into an extremely dense object roughly the size of Earth.
According to the researchers, the discovery shows that even the part of the Galaxy closest to us is far from being fully explored.
To date, only around 30 per cent of the nearest red dwarfs have been surveyed in detail. This means that there could be as many as nine or ten more such binary systems hidden near the Sun, which no one has yet discovered.
Background
White dwarfs are the most common final stage in the evolution of Sun-like stars. Despite their small size, their mass is comparable to that of the Sun, so the density of matter within them is extremely high.
Due to their faint glow and proximity to brighter stars, many white dwarfs remain hidden from observation for a long time.
Source
Mairi O’Brien et al. Direct detections of white dwarfs in four WD+dM post-common envelope binaries within 20 pc. Monthly Notices of the Royal Astronomical Society (2026).