This month's featured image from the NASA/ESA/CSA James Webb Space Telescope provides a detailed glimpse of the Herbig Haro object 797 (HH 797). Herbig-Haro objects, such as HH 797, are radiant areas encircling newly formed stars, specifically protostars. These objects take shape when the stellar winds or gas jets emitted by protostars generate shockwaves upon colliding with adjacent gas and dust at high velocities. HH 797, dominating the lower section of the image, is situated in proximity to the young open star cluster IC 348, found near the eastern edge of the Perseus dark cloud complex. The luminous infrared features in the upper part of the image are believed to harbor two additional protostars.
This captivating image was captured using the Webb's Near-InfraRed Camera (NIRCam). Infrared imaging proves instrumental in studying newborn stars and their outflows, especially since the youngest stars are typically still enveloped within the gas and dust from which they originate. In the case of Herbig-Haro objects, the infrared emission from the star's outflows permeates the obstructing gas and dust, rendering them well-suited for observation with Webb's highly sensitive infrared instruments.
Turbulent conditions within these regions excite molecules like molecular hydrogen and carbon monoxide, causing them to emit infrared light. Webb's NIRCam excels at capturing the structure of these outflows, particularly the hot molecules with temperatures reaching thousands of degrees Celsius, stimulated by shocks within the stellar environment.
Previous ground-based observations indicated intriguing characteristics of the cold molecular gas associated with HH 797. These findings revealed a spatial distribution where the majority of the red-shifted gas (moving away from us) was concentrated in the south (bottom right), while the blue-shifted gas (moving towards us) was situated in the north (bottom left). Additionally, a velocity gradient across the outflow suggested a rotation effect, leading astronomers to hypothesize a single outflow. However, the higher resolution image from the Webb telescope challenges this assumption, unveiling two nearly parallel outflows with distinct series of shocks, clarifying the observed velocity asymmetries.
The source, located in the small dark region at the bottom right of the center, previously identified as a single star, is now revealed as a double star, with each star generating its own dynamic outflow. The image also showcases other outflows, including one emanating from the protostar in the top right of the center, along with its illuminated cavity walls. Notably, HH 797 is positioned directly north of HH 211, separated by approximately 30 arcseconds, and HH 211 was featured in a Webb image release in September 2023.
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