The Hubble Space Telescope has made it possible to see plasma clumps almost twice the size of Mars, which the old star ejects at a speed of tens of thousands of kilometers per hour.
Astronomers have recorded traces of this unusual phenomenon for a long time, about once every 8.5 years, but now it has been observed in action for the first time. This allowed American scientists, led by Raghvendra Sahai, to hypothesize its causes. They write about this in an article published in The Astrophysical Journal.
Star V Hydra is a "swollen" red giant, which our Sun will become in a few billion years towards the end of its evolution. It is surrounded by a planetary nebula - a scattered cloud of matter ejected by a star and illuminated by its radiation. According to scientists, the star has already lost at least half of its mass and sluggishly burns out the remains of hydrogen. This weak thermonuclear reaction can hardly serve as a source of energy for the massive and rapid plasma clumps that Hydra V occasionally throws out. But these emissions themselves can fuel the growth of a planetary nebula.
The star was observed with the Hubble Space Telescope between 2002 and 2013, including during the last recorded plasma ejection in 2011. Spectroscopic data made it possible to determine the speed, trajectory, temperature and size of a series of clumps. In particular, they turned out to be almost twice as hot as the surface of the Sun - up to 9400 ° С. Noticeably cooled and less dense clumps were discovered 60 billion km from the star - this is the material ejected by it in previous periods, up to 1986.
Ragwendra Sahai and his colleagues have modeled various options for the appearance of these clumps, and calculations of one of the models pointed to the most probable cause: the influence of an invisible nearby star, which orbits V Hydra in about 8.5 years. Passing through the upper layers of the red giant's thin atmosphere, it attracts material that rushes towards the star, accelerating and spinning along the spiral of the accretion disk - so that some clumps "break" from the trajectory and, like from a sling, are shot away.
Photo: NASA, ESA, A. Feild (STScI)
According to scientists, the influence of the second star also explains the rapid growth of the planetary nebula around Hydra V, which was formed literally in front of astronomers over the past several hundred years. The Hubble images show that here and there, slowly “melting” and cooling clots of plasma are scattered here and there, apparently thrown out by a star.
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