Amazing Jets From Newly Forming Star.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
What is a Herbig-Haro Object? Dual jets of superheated gas escape in opposite directions form a newly forming star. These flows come in a variety of shapes and sizes.
Their basic formation is constant. It might look like a wisp of smoke, but this cosmic veil is billions of times more dense. In this image, the Hubble Space Telescope caught Herbig-Haro 110 spewing off its material like a fire hydrant. Instead of water, it splashes hot gas out, bouncing off the dense core of molecular hydrogen. It’s an awesome display that spans light years across! Astronomers theorize HH objects are formed when outflows are supplied by gas accreting against a young star still in its envelope of dust and gas. Like a fire hydrant, the disk is the water line, the star is the gravitational pump and the jets are the water stream. When the busy jets contact colder gas, the collision is like a fire hose pumping water against a brick wall.
Gas at the shock front slows to a stop, but, like the hose, the gas continues to flow forward as the jet keeps pumping into the shock from behind. Here temperatures rise dramatically as the curving, flared region begins glowing. These areas are called “bow shocks” because they resemble the waves created in front of a moving boat.
Why is Herbig-Haro 110 so different? In its singular circumstance, it doesn’t seem to have a source star to cause the jet flow. Study after study has failed to reveal one. If there is no driving star, then what causes it? Researchers think the HH 110 outflow may be caused by another jet… nearby HH 270. In this instance, 270 may be encountering a unseen, immovable obstacle such as a colder cloud core.
This could be diverting the flow at an angle. The jet would then go dark and as it comes to light again, it reinvents itself as HH 110.
What would happen if the water pressure didn’t remain steady at the fire hydrant? Of course, it would come out as surges! As fast moving pockets of gas catch up and combine with slowing moving ones, new shocks occur along the jet’s interior. The light which comes from these highly excited ridges appears blue and marks the edges of the interior collisions. Astronomers are able to determine the moment the surges occurred by measuring the speed and position of the ridges along the chain with in the jet. Using this information, they can trace the source star’s history of mass accretion.
Original Story Source: Hubble Site News Release.
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