Searching For Water In The Milky Way, Drier Than First Thought

Justin Streight

The Hubble Space Telescope finished another step in a important mission, looking for water in the milky way. The results so far are a bit surprising, with three exoplanets (planets outside the solar system) coming up short in their water supplies.

The three planets are called HD 189733b, HD 209458b, and WASP-12b. The three worlds are like Jupiters, large gas giants, but significantly hotter. The high temperatures were perfect for detecting water vapor and they did find some, just a surprisingly low amount, according to a NASA news release.

Water is believed to be an abundant resource in the milky way galaxy. Jupiter's icy moon Europa, for example, is believed to have a layer of liquid water under the surface and water vapor plumes that shoot up into space.

In another recent discovery, scientists found the largest body of water vapor in the known universe. The water vapor cloud, which surrounds a distant supermassive black hole, contains 4000 times more water vapor than in the milky way. To be fair, the milky way has most of its water locked up in ice.

Scientists have also estimated there are large amounts of water in formation of planets, a theory that might now have to be tweaked.

As Nikku Madhusudhan of the Institute of Astronomy at the University of Cambridge, England explained,

"Our water measurement in one of the planets, HD 209458b, is the highest-precision measurement of any chemical compound in a planet outside our solar system, and we can now say with much greater certainty than ever before that we've found water in an exoplanet. However, the low water abundance we have found so far is quite astonishing."

The current theory about how planets form in the milky way and beyond is called core accretion. Core accretion theory states that gravity brings together bits of hydrogen, helium, ice, and other space dust to eventually form the core of a new world. This new discovery is revealing that we might not yet understand the chemical recipe for an exoplanet.

"There are so many things we still don't know about exoplanets, so this opens up a new chapter in understanding how planets and solar systems form," said Drake Deming of the University of Maryland. "The problem is that we are assuming the water to be as abundant as in our own solar system. What our study has shown is that water features could be a lot weaker than our expectations."

(Image Credit: Greg Bacon/Wikimedia Commons)