Date:
Tue, 27/05/202512:30-13:30
Speaker: Dr. Shmuel Bialy (Physics Department, Technion – Israel Institute of Technology, Haifa)
Title: Cold Clouds as Cosmic Ray Detectors: First Detection of Cosmic-Ray Excited H_2 with JWST
Abstract:
Stars and planets form in the coldest, densest parts of interstellar space—dark molecular clouds where cosmic rays (CRs) are the main source of ionization, driving the chemistry and physics that regulate star formation. Yet measuring CR ionization in these regions has remained a long-standing challenge. In this talk, I will present new JWST observations of the starless core Barnard 68, revealing the first direct detection of H_2 emission excited by CRs—a signature long predicted but never observed. The emission pattern uniquely fingerprints CR excitation and allows a direct measurement of the ionization rate. I will also outline the theoretical framework behind this process. These results confirm a decades-old prediction and establish dense molecular clouds as natural, gigantic CR detectors—floating in space and spanning light-years—offering a powerful new way to trace CR propagation and their impact on star and planet formation.
Zoom link:
https://huji.zoom.us/j/87568723714?pwd=jt3DZDHWr6zpVHiTSNA0AoQ3baK1sh.1
Meeting ID: 875 6872 3714
Passcode: 751429
Contact: Sivan Ginzburg
Title: Cold Clouds as Cosmic Ray Detectors: First Detection of Cosmic-Ray Excited H_2 with JWST
Abstract:
Stars and planets form in the coldest, densest parts of interstellar space—dark molecular clouds where cosmic rays (CRs) are the main source of ionization, driving the chemistry and physics that regulate star formation. Yet measuring CR ionization in these regions has remained a long-standing challenge. In this talk, I will present new JWST observations of the starless core Barnard 68, revealing the first direct detection of H_2 emission excited by CRs—a signature long predicted but never observed. The emission pattern uniquely fingerprints CR excitation and allows a direct measurement of the ionization rate. I will also outline the theoretical framework behind this process. These results confirm a decades-old prediction and establish dense molecular clouds as natural, gigantic CR detectors—floating in space and spanning light-years—offering a powerful new way to trace CR propagation and their impact on star and planet formation.
Zoom link:
https://huji.zoom.us/j/87568723714?pwd=jt3DZDHWr6zpVHiTSNA0AoQ3baK1sh.1
Meeting ID: 875 6872 3714
Passcode: 751429
Contact: Sivan Ginzburg