Akari uncovers secrets of the cold and dusty Universe

Paris, Nov 20 : The Akari infrared surveyor, a Japanese Aerospace Exploration Agency mission with ESA (European Space Agency) participation, is uncovering a number of secrets of the cold and dusty Universe.

For example, Akari observations of Betelgeuse, a bright red supergiant star located in the constellation Orion about 200 light-years from Earth, show the star making a big splash by creating a bow shock as it crosses the interstellar medium.

The interstellar medium, a tenuous mix of gas and tiny solid dust particles, permeates space. As stars age, they spew out gas and dust in a flow called stellar wind, which eventually mixes with the interstellar medium.

At the interface between stellar wind and the interstellar medium, physical conditions such as density and pressure change dramatically, creating what is called a bow shock.

Researchers have found a strong flow of the interstellar medium around the star which originates from star-forming regions in Orion's Belt.

Stars condense out of the interstellar medium at birth, and old stars like Betelgeuse spew out matter into surrounding space, enriching the interstellar medium. This process is repeated by generations of stars and assists the chemical evolution of the Universe.

Akari has found a number of such bow shocks and investigation into these processes will further our understanding of the cosmic recycling of matter.

Other observations by the Akari are also intriguing.

An example is the observation of about eight of the 20 reported supernova remnants in the Large Magellanic Cloud revealing unexpected details.

The Large Magellanic Cloud is a companion galaxy of the Milky Way located at a distance of about 160 000 light-years from us.

Its relatively short distance and unique location provides a unique view of the entire galaxy from Earth and the possibility to study the interstellar medium.

Akari has found that supernova remnants in the Large Magellanic Cloud are surrounded by previously unknown warm dust.

This suggests that some dust grains survive the shock of the supernova explosion.

Further analysis with the Akari data will greatly improve our knowledge on supernova remnants and their influence on their surroundings.

ANI