Origin of the Local Ribbon of Cold Clouds (LRCC)

Identify the formation mechanisms and astrophysical origin of the Local Ribbon of Cold Clouds, including the Local Lynx of Cold Clouds (LxCC) encountered by the Sun 2–3 million years ago.

Background

To model the heliosphere’s interaction with a dense cold cloud, the study adopts physical parameters from the Local Leo Cold Cloud, a prominent component of the Local Ribbon of Cold Clouds.

The authors explicitly note that the origin of these cold clouds is unknown, even though their velocity field appears smooth and placid, underscoring a fundamental gap in understanding the LRCC’s provenance.

References

We don't know the origin of these clouds although LRCC has a very placid and smooth velocity field, so for the ISM outside the heliosphere, we adopted the characteristics of the LLCC32, namely, nH = 3,000 cm 3 and T = 20 K.

— Increased and Varied Radiation during the Sun's Encounters with Cold Clouds in the last 10 million years  (2601.11785 - Opher et al., 16 Jan 2026) in Methods: Description of the 3D MHD model