Gases collide in the heart of the Running Man nebula
Here is the Herbig-Haro object known as HH45, captured by the The Hubble Space Telescope (HST)! These objects are a rarely seen type of nebula made up of luminous clouds of dust and gas. These occur when newborn stars form in a nebula and eject hot gas, colliding with the surrounding gas and dust. The result is bright shock waves that resemble glowing mounded clouds in space!
In this image, HH45 is shown inside the NGC 1977 nebula, which is part of the larger complex of three nebulae called Running Man. The Hubble image successfully captured clouds of ionized oxygen (O II) and magnesium (Mg II), shown in blue and purple (respectively). These elements are of particular interest to researchers because they can identify shocks and ionization fronts with these objects.
Along with its companions, NGC 1975 and NGC 1973, NGC 1977 is one of three reflection nebulae that make up the Running Man Nebula located in the constellation Orion (just north of the massive Orion Nebula). The term Reflection Nebula refers to dusty, rapid clouds that do not emit light on their own but reflect light from nearby stars. In the case of NGC 1977, the whole region is turned on by hot young star 42 Orionis (HD 37018).
The same day as the image HH45 was released, NASA released a second image (below) of a star jet inside NGC 1977 visible at Hubble. The orange plasma jet (visible at the bottom center of the image) stretches two light years across space and was emitted by the young star Parengo 2042. This star is embedded in a disc of debris that could one day give birth to planets.
The red and orange colors in this image indicate the jet and the associated glowing shockwaves, which are visible due to the way they are powered by radiation from a nearby star – 42 Orionis. Although this star is not visible in the image, its bright light can be seen entering the lower right frame and extending across the lower half of the image.
On the right side of the image, there are bright blue ripples that appear to be moving away from the jet, which are arc shocks facing 42 Orionis. In space, bow shocks occur when gas streams collide and form crescent-shaped waves, similar to what ships at sea leave in their wake. Likewise, the shining west lobe of the jet is surrounded by a series of orange arcs that decrease in size with distance, forming what appears to be a conical shape.
Such jets are particularly useful for researchers because the outgoing gas remains visible thanks to ionizing radiation from nearby stars. Normally, the exit jets are only visible when they collide with the surrounding gas and dust, creating light shock waves that disappear when cooled. It also provides a visual representation of what Hubble was looking by observing this nebula.
Essentially, Hubble observes reflective nebulae like NGC 1977 in hopes of witnessing stellar jets and discs forming planets. The overall goal is to learn more about how the debris disks that planets form from are affected by ionizing radiation and other factors in their local environment. The data obtained from these types of observational campaigns ultimately allow astronomers to improve their models of planetary formation and help answer deeper questions of how and where life can emerge in our Universe.