The Hubble telescope has helped astronomers uncover the secrets of the strange system WOCS 14020, consisting of a “blue lurker” and an anomalous white dwarf. According to the researchers, in the past it consisted of three luminaries.

“Blue lurkers” in astronomy are stars that at first glance do not differ from ordinary luminaries, but at the same time have an anomalously high rotational speed that does not correspond to their age. In this way, they are similar to so-called “blue stragglers,” another type of “young” stars that have higher temperatures and luminosities than they should according to their age.
The researchers’ attention was drawn to one of these stars, which is part of the M67 star cluster. Its age is 4 billion years. This means that the period of rotation of the luminary should be of the order of 20-30 days. In reality, it makes one rotation around its axis in only 4 days, which is typical for very young luminaries. Another important feature is that the “blue straggler” has a companion, a white dwarf. Its mass is 0.72 solar masses, while in theory, hot white dwarfs in M67 should have masses of 0.5 solar masses or less.
To unravel the mystery of this system, scientists used Hubble. Analyzing its data allowed them to conclude that in the past this system was triple. However, about 500 million years ago, its two components merged to form a much more massive star. Soon it turned into a red giant and dropped matter. Part of it was absorbed by the third star, leading to its “unwinding” and rejuvenation.
As for the red giant, after the completion of the shedding of matter from it left a white dwarf with an anomalously large mass. It is a reminder of this star’s unusual past.
Earlier we reported on another unusual white dwarf that resisted being swallowed by a black hole.
According to Phys.org