Herbig-Haro objects HH 1 and HH 2 are located 1,250 light-years away in the constellation of Orion.
Two wispy, gaseous clouds occupy the corners of this image, HH 1 in the upper right, and HH 2 in the lower left. Both are light blue and surrounded by dimmer multi-colored clouds, while the background is dark black due to dense gas. A very bright orange star lies just to the lower left of HH 1, and beyond that star is a narrow jet, emerging from the dark center of the field. Image credit: NASA / ESA / Hubble / B. Reipurth / B. Nisini.
Herbig-Haro objects are small bright patches of nebulosity associated with newborn stars.
They were first observed in the 19th century by the American astronomer Sherburne Wesley Burnham, but were not recognized as being a distinct type of emission nebula until the 1940s.
The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named.
Herbig-Haro objects are formed when hot gas ejected by a newborn star collides with the gas and dust around it at speeds of up to 250,000 kmh (155,000 mph), creating bright shock waves.
They come in a wide array of shapes, the basic configuration is usually the same: twin jets of heated gas, ejected in opposite directions from a forming star, stream through interstellar space.
Herbig-Haro objects are transient phenomena — they disappear into nothingness within a few tens of thousands of years.
“HH 1 is the luminous cloud above the bright star in the upper right of this image, and HH 2 is the cloud in the bottom left,” Hubble astronomers said.
“While both Herbig-Haro objects are visible, the young star system responsible for their creation is lurking out of sight, swaddled in the thick clouds of dust at the center of this image.”
“However, an outflow of gas from one of these stars can be seen streaming out from the central dark cloud as a bright jet.”
“Meanwhile, the bright star between that jet and the HH 1 cloud was once thought to be the source of these jets, but it is now known to be an unrelated double star that formed nearby.”
The color image of HH 1 and HH 2 was made from separate exposures taken in the ultraviolet, visible and infrared regions of the spectrum with Hubble’s Wide Field Camera 3 (WFC3).
Eleven filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.
“Each of these filters is sensitive to just a small slice of the electromagnetic spectrum, and they allow astronomers to pinpoint interesting processes that emit light at specific wavelengths,” the researchers explained.
“In the case of HH 1 and HH 2, two groups of astronomers requested Hubble observations for two different studies,” they added.
“The first delved into the structure and motion of the Herbig-Haro objects visible in this image, giving astronomers a better understanding of the physical processes occurring when outflows from young stars collide with surrounding gas and dust.”
“The second study instead investigated the outflows themselves to lay the groundwork for future observations with the NASA/ESA/CSA James Webb Space Telescope.”
“Webb, with its ability to peer past the clouds of dust enveloping young stars, will revolutionise the study of outflows from young stars.”
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