Star formation more `intense and dynamic` than previously believed

Last Updated: Wednesday, August 21, 2013 - 15:37

Washington: Powerful jets of gas and other raw material outward while star formation is taking place, a according to a new research.

Analysis of fresh high-resolution images of fast-moving emissions from a well-known protostar refines the existing picture of the outflows` size, shape, and motion, and shows that they are moving at greater velocities than previously measured.

The outflows have a pronounced effect on the host cloud, pushing dense raw materials away and affecting cloud properties, such as turbulence, according to the research team, led by Yale University astronomer Hector Arce. This in turn affects development of the protostar itself, possibly influencing the star`s ultimate characteristics and the cloud`s ability to form other stars.

Arce, associate professor of astronomy at Yale, said that if they can see these interesting features for this `run-of-the-mill` protostar, we should expect to see similar features in other protostars.

Their research is part of a broad effort by astronomers to better understand formation of stars like Earth`s Sun and the environment where this happens.

Arce said that the Sun is a star, so if it people want to understand how the solar system was created, they need to understand how stars are formed.

The new research focuses on HH 46/47, the bipolar outflow from a protostar forming on the outskirts of the Gum Nebula, at about 1,400 light-years away. The researchers used observations from the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile.

Arce said that assuming HH 46/47 is broadly representative of protostellar outflows that their results imply that outflows have much more momentum and kinetic energy, and therefore significantly more impact on their surroundings, than previously believed.

He said that this indicates that protostellar outflows could provide the energy to sustain turbulence in the clouds where stars form and even help in dispersing the gas around newly formed stars.

The recent paper describes the two lobes of the HH 46/47 outflow in detail, noting striking differences in size, shape, and complexity.

The research shows the outflow is episodic, suggesting that star growth itself may be episodic, researchers said.

Arce said that the mass of the star does not increase smoothly over time as disk material accretes at a constant rate onto the star.

He said that instead, the star mostly gathers mass through episodes of high mass-accretion rates, separated by periods of low accretion rates.

Co-author Diego Mardones of the Universidad de Chile, said that because of the location of this protostar at the edge of the molecular cloud, one outflow lobe interacts with the interior, or denser part, of the cloud on one side of the protostar, and the other lobe emerges on the other side.

He said that this makes it an excellent system to study the impact of stellar winds on different kinds of environments.

The findings have been reported in Astrophysical Journal.

ANI



First Published: Wednesday, August 21, 2013 - 15:36

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