Hubble spots dying star ejecting massive ‘space cannonballs’

Space pirates may not be a real thing (yet) but apparently space cannonballs are, according to new research published in a recent edition of The Astrophysical Journal which describes volleys of superhot plasma blobs a dying star has been shooting off for centuries.

As researchers from the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California explain in a statement, these fireballs originate from the star known as V Hydrae, a red giant about 1,200 light-years from Earth that has lost at least half of its mass to space during its final days.

Using Hubble’s Space Telescope Imaging Spectrograph (STIS), the JPL researchers observed the V Hydrae system for an 11-year period from 2002 to 2004, and from 2011 to 2013. They found a series of enormous blobs with temperatures exceeding 17,000 degrees Fahrenheit (9,400 Celsius) or nearly twice that of the sun. They went on to create a detailed map of their locations.

However, the gas blobs, each of which are said to be twice as massive as Mars traveling through space at speeds that would allow them to go from Earth to the moon in just half an hour, could not have actually come from the star itself. In fact, some of them originated from as far as 37 billion miles (60 million km) away from V Hydrae.

star ejecting gas

This graphic shows how the binary-star system launches balls of plasma into space. (Credit: NASA, ESA, and A. Feild (STScI))

So where did these so-called ‘space cannonballs’ come from?

Rather, the JPL researchers believe that an unseen companion star is responsible for the plasma volleys, which have come once every 8.5 years for at least the last 400 years, according to their estimates. Said companion would have to be traveling in an elliptical orbit that brings it close to V Hydrae on a regular basis, where it consumes material that settles into its disk.

As the companion star continues along its orbit, it tends to fire off these plasma blobs at speeds of up to 500,000 mph. These gas balls expand and cool as they move further away, and although they cannot be detected in visible light, observations collected in sub-millimeter wavelengths in 2004 reveal that they have been launched since at least 1986 and perhaps even as far back as 400 years ago.

“We knew this object had a high-speed outflow from previous data, but this is the first time we are seeing this process in action,” explained Raghvendra Sahai, a researcher at JPL and the lead author of the August paper. “We suggest that these gaseous blobs produced during this late phase of a star’s life help make the structures seen in planetary nebulae.”

“The observations show the blobs moving over time,” Sahai said. Using the data they collected, the JPL team was able to develop a model of a companion star with an accretion disk to explain the ejection of these superhot gas balls. “This model provides the most plausible explanation,” he continued, “because we know that the engines that produce jets are accretion disks.”

“Red giants don’t have accretion disks, but many most likely have companion stars, which presumably have lower masses because they are evolving more slowly,” Shai concluded. “The model we propose can help explain the presence of bipolar planetary nebulae, the presence of knotty jet-like structures in many of these objects, and even multipolar planetary nebulae. We think this model has very wide applicability.”


Image credit: NASA/Hubble