Congratulations to our friends and collaborators on the SwRI-led NASA New Horizons mission for achieving an astounding milestone! It has successfully initialized all-important first Lyman-alpha map of the galaxy. This monumental success was the result of years of detailed observations of Lyman-alpha emissions. As New Horizons journeyed further into the deep solar system, it picked up this particular wavelength of ultraviolet light emitted and scattered by hydrogen atoms.
The New Horizons spacecraft, with its far-ultraviolet instrument called Alice, scanned for Lyman-alpha emissions along its path. The images show a very consistent, background sky brightness for Lyman-alpha light. This brightness was an order of magnitude brighter than previously measured. By the end of 2023, the mission had finished a very ambitious series of scans, mapping about 83% of the entire sky.
Dr. Randy Gladstone was the principal investigator of this landmark study and is first author of the paper. His space age research has revealed that the solar system is embedded in a bubbling hot interstellar gas medium. This bubble could explain the high level of hydrogen gas emissions recently observed in Lyman-alpha light.
Observations and Findings
Thanks to the eyes of New Horizons, we have been granted a glimpse of the newly discovered qualities that permeate the sky around our solar system. Our map illuminates some important NGP & SGP indicators, north and south galactic poles. It further shows the direction of flow of the interstellar medium as it penetrates into the solar system, upstream and downstream.
As Dr. Alan Stern, the Principal Investigator of New Horizons, said in making these observations so special, it really was the first time. He stated,
“These are really landmark observations, in giving the first clear view of the sky surrounding the solar system at these wavelengths, both revealing new characteristics of that sky and refuting older ideas that the Alice New Horizons data just doesn’t support.”
Those observations have helped to make clear that Lyman-alpha emissions result from much more than the sun’s own heliosphere. Like our local bubble, they’re shaped by ancient mosaics of interstellar gas bubbles and supernova explosions that happened millions of years ago.
Implications for Future Research
This study is more than just correlative observations. Beyond mapping the stars, it serves as a robust starting point for future explorations into galactic architectures and mechanisms. Dr. Gladstone noted,
“Understanding the Lyman-alpha background helps shed light on nearby galactic structures and processes.”
The map features more than 90,000 identified UV-bright stars, shown in the maps with black dots. This new addition greatly expands and improves the data available to astronomers and amateur researchers alike.
“This research suggests that hot interstellar gas bubbles like the one our [solar system] is embedded within may actually be regions of enhanced hydrogen gas emissions at a wavelength called Lyman alpha.”
This study has some surprising news. In doing so, it finds no evidence for the so-called hydrogen wall that many scientists expected to exist around the sun’s heliosphere. This result calls into question previous theories on the role of hydrogen in producing the observed Lyman-alpha signal.
Revising Previous Theories
While scientists are still working hard to digest these findings, hope is indeed on the horizon. Dr. Stern remarked,
Astronomers are just beginning to probe a recently made map, giving them their best look yet at the broader cosmic picture surrounding our solar system. This achievement educates them about more global galactic phenomena.
“This Lyman-alpha map also provides a solid foundation for future investigations to learn even more.”
By examining this newly created map and its implications, astronomers now have a clearer view into understanding not only our solar system’s immediate environment but also broader galactic phenomena.