Dying red star sheds giant fireball tears

NEW DELHI: A red giant star some 1200 light years away is going through bizarre death throes. NASA's Hubble Space Telescope detected superhot blobs of gas being shot out like gigantic cannon balls every 8.5 years from near the star. These plasma balls, travelling at a jaw dropping 800,000 kilometers per hour are each twice as massive as the planet Mars. The plasma balls are zooming so fast through space it would take only 30 minutes for them to travel from Earth to the moon.

This weird phenomenon is puzzling scientists because the host star, called V Hydrae is a bloated red giant, which means that it is in the late stages of life. The current best explanation suggests the plasma balls are launched by an unseen companion star going around in an elliptical orbit that carries it close to the red giant's puffed-up atmosphere every 8.5 years. As the companion enters the bloated star's outer atmosphere, it gobbles up material. This material then settles into a disk around the companion, and serves as the launching pad for blobs of plasma.

"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," said Raghvendra Sahai of NASA's

Jet Propulsion Laboratory

in Pasadena, California, lead author of the study. "We suggest that these gaseous blobs produced during this late phase of a star's life help make the structures seen in planetary nebulae."

"We want to identify the process that causes these amazing transformations from a puffed-up red giant to a beautiful, glowing planetary nebula," he said. "These dramatic changes occur over roughly 200 to 1,000 years, which is the blink of an eye in cosmic time."

Sahai's team used Hubble's Space Telescope Imaging Spectrograph (STIS) to conduct observations of V Hydrae and its surrounding region over an 11-year period, first from 2002 to 2004, and then from 2011 to 2013. Spectroscopy decodes light from an object, revealing information on its velocity, temperature, location and motion.

The data showed a string of monstrous, superhot blobs, each with a temperature of more than 9,400 degrees Celsius -- almost twice as hot as the surface of the sun. The researchers compiled a detailed map of the blobs' locations, allowing them to trace the first behemoth clumps back to 1986. "The observations show the blobs moving over time," Sahai said. "The STIS data show blobs that have just been ejected, blobs that have moved a little farther away, and blobs that are even farther away." STIS detected the giant structures as far away as 37 billion miles (60 million kilometers) away from V Hydrae, more than eight times farther away than the Kuiper Belt of icy debris at the edge of our solar system is from the sun.

The blobs expand and cool as they move farther away, and are then not detectable in visible light. But observations taken at longer, sub-millimeter wavelengths in 2004, by the Submillimeter Array in Hawaii, revealed fuzzy, knotty structures that may be blobs launched 400 years ago, the researchers said.

Based on the observations, Sahai and his colleagues

Mark Morris

of the University of California, Los Angeles, and

Samantha Scibelli

of the State University of New York at Stony Brook developed a model of a companion star with an accretion disk to explain the ejection process. The team's results appeared in the August 20, 2016, issue of The Astrophysical Journal.