Milky Way's Sagittarius A* black hole killing red stars with giant ray?

During the 1990s, astronomers had noticed a big lack of red giant stars in the Milky Way’s centre. There have been various theories circulating around the noticeable absence. A new theory has now proposed a truly frightening phenomenon; it states that a huge jet that is launched from the galaxy’s massive black hole has destroyed the red giants that wandered in its path. Here is a look at the new theory according to Space.com.

Red Giant stars

Astronomer Kris Skellgren had noticed the lack of carbon monoxide (CO) in the light coming from stars near the galactic centre in 1990. It is commonly found in the upper atmospheres from the red giant stars. The report mentions that there are about 1000 missing red giants in the Milky Way’s centre. The red giant stage is the last phase of any sunlike star’s life. The stars turn red after swelling once they stop fusing hydrogen in the cores thus getting the name red giants. They are found all over the disk of the Milky Way.

Over the years, astronomers have come up with several ideas and theories most of which centre around Sagittarius A*. It is a supermassive black hole at the galactic centre. It weighs over 4.5 million times the mass of the sun. With such mass, Sagittarius A* can do a lot of things including killing the red giants. Therefore it is possible that Sagittarius A* rips apart the stars like red giants which wander too close to it. It is also possible that the red giants collide with other remnants near the Sagittarius A*.

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The new theory of jets killing off Sagittarius A*

In addition to such theories, astronomers have now come up with a theory that says the red giants are getting killed off by a giant ray in space. The report added that black holes like Sagittarius A* can launch massive jets of radiation and high-energy particles. These are not thrown by the black holes themselves but by the gas and dust that swirls around them in the form of an accretion disk. These disks are host to intense electric and magnetic fields. The fields are capable of forcing particles to flow around the black hole and up into jets.

When a giant black hole like Sagittarius A* is actively feeding on new material, the jets can reach tens of thousands of light-years, clearing out of their host galaxies altogether. The Sagittarius A* is also expected to have had such episode as evidenced by the so-called Fermi Bubbles. They are thin but have very vast regions of high energy particles that glow in gamma rays. Astronomers believe that the bubbles were formed by an intense jet coming from Sagittarius A*.

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When a red giant crosses the path of such a jet, it is capable of stripping away the outer layer of the star’s atmosphere. This leaves behind a burnt husk which is a relative cinder compared to the original red giant star. If this happens repeatedly, the jet could remove red giants near Sagittarius A*. This combined with other processes like a collision of a red giant and a black hole, tidal disruption of red giants and red stars plunging through the accretion disk could explain the killing of red stars.

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However, the report mentioned that Sagittarius A* is not currently feeding and does not have a strong jet. It is not actively forming bubbles and the event leading to the formation of Fermi Bubbles has happened in the past. The events may have happened in the past but that will not stop new giants from forming.

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