Watch a zombie star feed on its companion

The strange binary system R Aquarii spews material into the interstellar medium like a lawn sprinkler as its stars interact.
By | Published: October 30, 2024

“Watch out for rambunctious stars. They are trouble,” says Astronomy Editor David Eicher. The Hubble Space Telescope (HST) just published a new photograph showing the stunning masterpiece that is R Aquarii, lying about 700 light-years away in the constellation Aquarius the Water-bearer. It is an uncommon type of binary star system displaying chaotic behavior and enveloped by a large nebula — in this case, some of its boundaries reach about 250 billion miles (400 billion kilometers) from the system’s center.

The multicolored filaments shown in the HST photograph are created when the two components of a symbiotic binary star system interact. The pair is made of a white dwarf (the remnant of a Sun-like star) and a red giant (a stage in a Sun-like star’s life that occurs its dying process begins). The red giant is a variable star about 400 times larger than the Sun. Its brightness changes by a factor of 750 times over the course of a little more than a year and at its peak, it’s almost 5,000 times brighter than our star.

Despite the red giant’s variability, the white dwarf still benefits from its companion with each close pass, which happens once every 44 years. At those times, the white dwarf steals hydrogen from the red giant. Once the amount of gas reaches a certain limit, it is expelled in a powerful explosion. The ejected material is shaped into twisted filaments by the force and spread out by the stars’ strong magnetic fields.

R Aquarii is one of the closest known symbiotic binaries and was first spotted by Edwin Hubble in 1939. Nearly 30 years later, the system’s jets were found to be blasting in opposite directions from the center, spewing plasma all about. HST has been keeping a close watch on the system since 1990. Now, the European Space Agency and HST teams have enough photos to create the timelapse video below.