Herbig-Haro Objects

As we have seen, a young star has strong winds and matter trying to accrete onto the star may be heated and ejected in jets along the axis of rotation (bipolar outflow). As this ejected material slams into the gas and dust lying between the stars (the interstellar medium), it tends to form nebulosity at the ends of the oppositely directed jets. The following image shows a Hubble Space Telescope observation of such a situation in the vicinity of the Orion Nebula.

Such bright patches of nebulosity moving away from protostars and very young stars are called Herbig-Haro Objects. In the above image, the young star responsible for the jets and the nebulae at either end of the jets is hidden in the dark dust cloud lying in the center of the image. The entire width of this image is about one light year.

The following Hubble Space Telescope image shows another jet from a young star. Designated HH-47, this five-trillion-kilometer-long jet (half a light year) originates from a star hidden in a dust cloud near the left edge of the image. The twisted nature of the jet suggests that the star emitting it is wobbling on its rotation axis, perhaps because of interaction with another star. The Herbig-Haro object HH-47 is about 1500 light years away, lying at the edge of the Gum Nebula, which is possibly an ancient supernova remnant.