Feeding galaxy explains how gases are absorbed in star formation

An international group of astronomers has spotted a distant galaxy hungrily snacking on nearby gas.

Updated: Jul 05, 2013, 12:41 PM IST

Washington: An international group of astronomers has spotted a distant galaxy hungrily snacking on nearby gas.

The gas is seen to fall inward toward the galaxy, creating a flow that both fuels star formation and drives the galaxy`s rotation.

This is the best direct observational evidence so far supporting the theory that galaxies pull in and devour nearby material in order to grow and form stars.

Spiral galaxies like our own Milky Way formed billions of years ago in the dark matter concentrations that began to grow shortly after the Big Bang.

As gas cooled and condensed, stars formed, which, over time, synthesized heavy elements and polluted the galaxy with this enriched material upon their death.

But what that model has not been able to explain is the continuous formation of stars in some galaxies, despite the constant rate at which galaxies turn molecular gas into stars.

The simplest model calls for a closed system and predicts star formation should have ceased long ago due to the limited gas supply.

Galaxies should use up their gas on a time scale that`s much shorter than what has been observed, UC Santa Barbara astrophysicist Crystal Martin said.

In fact our own galaxy should have already run out of gas, but stars continue to form in it. "Galaxies must have a mechanism for acquiring more gas," she continued, adding that, historically, no means has existed to directly detect the inflow of the cold fuel.

Now, however, thanks to the background light from the quasar HE 2243-60, Martin and her colleagues have been able to observe distinct signatures near a typical star-forming galaxy that indicate the inflow of gas feeding the galaxy.

In this scenario, gas is drawn into a galaxy and then circles around it, rotating with it before falling in.

Although some evidence of such accretion had been observed in galaxies before, the motion of the gas and its other properties had not been fully explored until now.

The findings are set to be published in the journal Science.