42 Hydrogen Line linkage…
ALMA observes a magnetic field in a protoplanetary disk for the first time
6 February, 2025
Ohashi, S., Muto, T., Tsukamoto, Y. et al. Observationally derived magnetic field strength and 3D components in the HD 142527 disk. Nat Astron 9, 526–534 (2025). https://doi.org/10.1038/s41550-024-02454-x
“To study the origin of life, it is important to understand how Earth-like planets form. It has been thought that a planet forms by gradually accumulating interstellar dust and gas within a protoplanetary disk surrounding a young star. However, there are still many mysteries about the environment of planet formation and physical conditions inside the protoplanetary disk.
One of those mysteries is the magnetic field. It is thought to be a crucial factor in determining the turbulence and the movement of matter in a protoplanetary disk. Nevertheless, observing the magnetic field in a protoplanetary disk has been challenging. The magnetic field is an invisible vector field produced by a magnet or electric current. The magnetic field influences matter and energy like Earth’s magnetic field. This invisible force exists everywhere in the Universe and has much to do with star and planet formation.”
https://www.nature.com/articles/s41550-024-02454-x
Discovery of Radio Recombination Lines from Proplyds in the Orion Nebula Cluster
Draft version March 6, 2025
Ryan D. Boyden, Kimberly L. Emig, Nicholas P. Ballering, Charles J. Law, Thomas J. Haworth, Jonathan C. Tan, L. Ilsedore Cleeves, Zhi-Yun Li1
“In this paper, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations that, for the first time, detect hydrogen and helium radio recombination lines from proplyds in the ONC. Radio recombination lines are electronic spectral line transitions associated with high principal quantum numbers; they are emitted when a free electron recombines with an ion and passes through high-quantum-number energy levels while cascading down to lower energy levels.” (Gordon & Sorochenko 2009; Draine 2011).
https://arxiv.org/pdf/2503.02979
ALMA Reveals Hydrogen Glow Around Planet-Forming Disks in Orion
9 April, 2025
“Most stars form in molecular clusters, with specific environmental conditions dictating how planetary systems develop. Nearby massive stars can also influence by intense ionizing radiation, which can create a shell of ionized gas around a protoplanetary disk and emit unique hydrogen recombination spectral lines.
Recently a scientific team led by Ryan Boyden (University of Virginia) has used archive Atacama Large Millimeter/submillimeter Array (ALMA) data to identify for the first time the characteristic radio recombination lines associated with these ionized shells surrounding Solar System-sized protoplanetary disks in the Orion Nebula Cluster, at 1000 light-years from us.
Although ionized hydrogen is common in energetic environments such as these star-forming regions, Boyden and his team searched for the specific energy signature released when a free electron combines with a hydrogen ion and “falls” from hydrogen’s 42nd energy level to its 41st. That fall, called the H41α recombination line, is distinctly recognizable within the 3.1-mm radio wavelengths observed by ALMA. “
“In addition to the H41α recombination lines, Boyden and his team also identified intriguing He41α lines, indicating a potential difference from the expected abundance of helium in the region. Boyden acknowledges that adjacent carbon emissions may contaminate these helium lines, and he speculates on the next steps in the technological development of radio telescope interferometry. “With the upgrades coming to ALMA and ngVLA in the future, they will be able to excel at longer wavelengths for even more radio recombination lines. This project is a steppingstone for future work.”