NASA’s New Horizons spacecraft has achieved a groundbreaking milestone by producing the first-ever Lyman-alpha map of our galaxy, offering unprecedented insights into the interstellar medium surrounding our solar system.
Key Points at a Glance
- New Horizons created the inaugural map of Lyman-alpha emissions, a specific ultraviolet light emitted by hydrogen atoms, across the galaxy.
- The spacecraft’s Alice ultraviolet spectrograph, developed by SwRI, was instrumental in capturing these emissions during its journey beyond Pluto.
- Findings suggest our solar system resides within a ‘hot bubble’ of enhanced hydrogen emissions, likely formed by ancient supernovae.
- Contrary to earlier theories, the study found no significant evidence of a hydrogen wall at the heliosphere’s boundary.
- This map lays a foundation for future studies of the interstellar medium and galactic dynamics.
The New Horizons mission, renowned for its historic Pluto flyby, has ventured deep into the Kuiper Belt, enabling it to observe the cosmos from a uniquely distant vantage point. Using its Alice ultraviolet spectrograph, New Horizons has mapped the galaxy’s Lyman-alpha emissions—ultraviolet light produced by abundant hydrogen atoms—in an unprecedented scientific feat.
During observations conducted in 2023, the spacecraft captured data covering 83% of the sky. These observations revealed a uniform but unexpectedly strong background of Lyman-alpha emissions, around ten times more intense than previous models had predicted. This suggested a more dynamic and complex interstellar environment than previously imagined.
One of the most striking findings is the identification of a ‘hot bubble’ around our solar system. This region, with enhanced hydrogen emission, likely formed from shockwaves produced by nearby supernovae millions of years ago. Understanding such structures can illuminate the history of our cosmic neighborhood and the forces shaping it.
The study also challenges the long-standing hypothesis of a hydrogen wall—a supposed build-up of hydrogen at the boundary of the heliosphere caused by solar wind interaction with interstellar gas. Data from New Horizons showed no substantial evidence supporting this theory, prompting scientists to reconsider models of the solar system’s edge.
Dr. Randy Gladstone, principal investigator of the study, emphasized the significance of these insights: “Understanding the Lyman-alpha background helps shed light on nearby galactic structures and processes.” The comprehensive UV map not only expands our grasp of the interstellar medium but also charts a course for future missions probing the outer reaches of our galaxy.
The findings, published under the title “The Lyman-alpha Sky as Observed by New Horizons at 57 AU,” appeared in The Astronomical Journal. It marks a major milestone in our journey to comprehend the unseen architecture of the Milky Way.
Source: Southwest Research Institute
