Dust astrophysics has traditionally described grain alignment and disruption in three-dimensional space under steady irradiation. Cosmic transients introduce a fourth dimension: time. 

How does dust respond to sudden radiation flash from cosmic transients—and what does it remember after the flash has faded? 

In two new papers, we introduce TransRAT (Transient RAdiative Torque), a time-domain framework that follows grain heating, magnetic susceptibility, fast alignment, the transition from magnetic-field alignment (B-RAT) to radiation-direction alignment (k-RAT), and the rotational disruption of large grains by radiative torques, and predict photometric and polarimetric observables. Applied to a molecular cloud illuminated by a Type IIP supernova, TransRAT shows that enhanced alignment and the altered grain-size distribution can persist as physical memory, leaving fossil imprints such as enhanced polarization, a blueward-shifted polarization peak, polarization-angle reverberation, and modified extinction. The accompanying animation illustrates these physical processes. Read Paper I and Paper II.

July 10, 2026

thiem Hoang Proposes a new model for the extraterrestrial origin of homochirality

• Homochirality of biological molecules is the unique biosignature of life on Earth, as discovered by Louis Pasteur in 1843: amino acids are left-handed and sugars are right-handed. The exact origin of homochirality has remained an open problem for more than a hundred years. Our two new papers (Paper1 and Paper2) proposed a new model for the symmetry breaking of chiral molecules due to spin-polarized electrons (SPEs, electrons with aligned spins) produced by the alignment of icy grains with magnetic fields in protostellar environments. This model unveils the crucial role of dust-magnetic field-electron spins in understanding the extraterrestrial origin of life.