Hubble movies show supersonic stellar jets in motion

Combined Hubble images show jets in motion from young stars.

Some of the most mind-bending news from last week came from an international team of astronomers from NASA and the European Space Agency (ESA). The team combined two decades of Hubble Space Telescope images to produce short movies of the jets released during star birth.

Here’s one of the movies. Before you start thinking it’s not very exciting, remember two things. First, these jets are 10 times the width of our solar system. Second … we’ve never actually seen jets from celestial bodies in motion before now.

Astronomical processes occur so slowly relative to a human scale that it is usually impossible to view them in real time. We see objects in space as “snapshots,” their motions and processes visually static, for the most part. But because of Hubble’s precise ability to photograph, astronomers were able to discern changes in the jets released from newly forming stars over the course of just a couple of decades. Stitching together two decades of photographs from Hubble allowed astronomers to see the movement of the jets for the first time.

Stars – including our sun – are thought to form from great clouds of gas and dust in space. As they form, they are seen to release supersonic jets of gas and matter that can travel as fast as 100 miles per second. Newly forming stars with jets are called Herbig-Haro (HH) objects, after astronomers George Herbig and Guillermo Haro. The stellar jets seem to form as the swirling cloud of dust and gas surrounding a new star escapes.

Scientists hope videos such as this one will enable them to gain a better understanding of the processes that occur during star formation. They hope that that understanding, in turn, will lead to new insights on how our own sun, and therefore solar system, began.

Led by astronomer Patrick Hartigan of Rice University in Houston, the team used computer simulations and consulted fluid dynamics experts to create the movies. What they discovered is that jets from forming stars do not flow in a steady stream, but rather seem to pulse. The pulsing might allow scientists to glean information, such as when certain materials fell into a star.

The same jet photographed in 1994, 1998, and 2007. Image Credit: NASA, ESA, and P. Hartigan (Rice University)

Hartigan said in an ESA press release:

For the first time, we can actually observe how these jets interact with their surroundings by watching these time-lapse movies. Those interactions tell us how young stars influence the environments out of which they form. With movies like these, we can now compare observations of the jets with those produced by computer simulations and laboratory experiments to see what aspects of the interactions we understand and what parts we don’t understand.

All of the jets observed are, on a universal scale, very close to Earth – within about 1,350 light-years. The jets themselves are about 10 times the width of our solar system. Hubble used its Wide Field Planetary Camera 2 in photographing the jets.

The location of the jets in the Orion constellation. Image Credit: Z. Levay (STScI), T.A. Rector (University of Alaska, Anchorage), and H. Schweiker (NOAO/AURA/NSF)

Astronomers are still unsure what role the jets play in star and solar system formation, and exactly how the jets form. The next step for the team is to conduct lab experiments at the Omega Laser Facility in New York on the interaction of jets with their environments, a process that has already begun, according to an ESA press release.

Hartigan’s team’s results appeared in the July 20, 2011 issue of The Astrophysical Journal.

Bottom line: Led by astronomer Patrick Hartigan of Rice University in Houston, a team of scientists from NASA and ESA combined two decades of Hubble images to produce short movies of the supersonic jets released during star birth. They hope these movies – which show Herbig-Haro objects (HH objects) – will enable them to gain more understanding of how stars form, and in turn shed light on how our own sun and solar system began.

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