2025/01/30 by Nabeel Rehemtulla, Rehemtulla, Nabeel, W. V. Jacobson-Galán +56 · 4 citations
Physics and Astronomy · #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · pdf · doi:10.48550/arxiv.2501.18686
openalex publication_date 2025/01/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present observations of the Type IIP supernova (SN) 2024jlf, including spectroscopy beginning just 0.7 days (∼17 hours) after first light. Rapid follow-up was enabled by the new BTSbot-nearby program, which involves autonomously triggering target-of-opportunity requests for new transients in Zwicky Transient Facility data that are coincident with nearby (D<60 Mpc) galaxies and identified by the BTSbot machine learning model. Early photometry and non-detections shortly prior to first light show that SN 2024jlf initially brightened by >4 mag/day, quicker than ∼90% of Type II SNe. Early spectra reveal weak flash ionization features: narrow, short-lived (1.3 < τ~[d] < 1.8) emission lines of Hα, He II, and C IV. Assuming a wind velocity of vw=50 km s-1, these properties indicate that the red supergiant progenitor exhibited enhanced mass-loss in the last year before explosion. We constrain the mass-loss rate to 10-4 < M~\mathrm[M_\odot~yr-1] < 10-3 by matching observations to model grids from two independent radiative hydrodynamics codes. BTSbot-nearby automation minimizes spectroscopic follow-up latency, enabling the observation of ephemeral early-time phenomena exhibited by transients.