We can finally know the origin of the mysterious current that revolves around the galaxy

Germangendra is like the earth surrounded, but the whole galaxy has been rinsed. A huge, high-velocity stream of gas is wrapped around the Milky Way, about 200,000 light-years away, most of the way.

We know where it comes from, more or less. It is very closely linked to the large and small magellanic clouds, the dwarf galaxies that fill the orbit and will eventually be demonized by the galaxy. This cosmic snake gets its name – the Magellanic stream.

However, although the Magellanic current chemically matches the Magellanic Clouds, there is one aspect that has plagued astronomers for decades – its mass. That stream is worth about a billion solar mass gases, and the models could not explain why the two satellite galaxies are losing so much.

“That’s why,” explained Elena D’iangia, an astronomer at the University of Wisconsin-Madison, “we came up with a new solution that’s excellent at explaining the mass of currents.”

According to their new model the gas does not come from the Magellanic Clouds alone. Rather, it is drawn from their galaxy – huge clouds of gas and plasma that envelop most galaxies.

Magellanic flowAll-sky view of the Magellanic stream. (D. Nidivar et al., NRAO / AUI / NSF, A. Melinger, Leiden-Argentina-Bone Survey, Parks Observatory, Westerbark Observatory, Arecibo Observatory)

The dance of the Magellanic Clouds and the Milky Way is an interesting one, in which two satellite galaxies revolve around each other, and then orbit a huge galaxy together. This complex interaction is believed to be enveloping all three galaxies and disrupting the Milky Way galaxy clouds.

Previously, it was believed that the tidal rupture from the galaxy caused the magellanic current to be stretched as two dwarf galaxies come into the Milky Way galaxy under the influence of gravity. But this model only accounts for about 10 percent of the observed mass of the flow.

“This is a 50-year-old puzzle,” said Andrew Fox, an astronomer at the Space Telescope Science Institute. “We never had an explanation as to where it came from. The really surprising thing is that we’re closing in on a revelation now.”

What’s new here is recent research that suggests the Magellanic Clouds are spacious enough to have their own closet.

The team, led by University of Wisconsin-Madison astronomer Scott Luchini, performed their own simulations of the Magellanic Clouds being drawn into orbit around the galaxy.

They calculated that the halo of hot gas around the Magellanic Clouds – known as the Magellanic Corona – would have dramatically changed the way Magellanic currents formed.

According to their simulations, formation was a two-stage process. The first phase occurred long before the Magellanic Clouds were captured by the galaxy, but when they were still orbiting each other. Large Magellanic Cloud has stolen a bunch of stuff from the Small Magellanic Cloud, losing a small amount of gas.

The process took about 7.7 billion years, with the influence of about a billion billion solar masses of gases capturing the Milky Way galaxy. At this stage, the gravitational forces sowed the seeds for the magellanic flow, the halo providing about 10 to 20 percent of its final mass.

Animation MCAnimation of the simulation. (Elena de Onthia and Scott Luchini / University of Wisconsin-Madison)

In the second phase, after capturing two orbits of the galaxy, to create the rest of the flow, the gravity of our galaxy and its interaction with its own galactic halo, stretches around one-fifth of the mass of the Magellanic corona.

According to the team’s simulations, this two-phase chronology reproduces the formation and mass of the Magellanic current, including the branch of the current known as the leading arm, orbiting two dwarf galaxies.

We haven’t found Magellanic Corona directly yet, but the team model provides a toolkit to do so.

The gas cloud should have an ionized state of carbon and silicon. Using the Hubble Space Telescope, we can see distant quarters through the Magellanic corona, and analyze their light to see if it has passed through significant clouds of this material on its way to the solar system.

The researchers wrote in their paper that “background-quasar perspectives provide an opportunity for a vague investigation of the magellanic corona, as they are disjointed by the intermagnetic content of the large magellanic cloud,” the researchers wrote in their paper.

Research has been published in Nature.