Year: 2026
Type: article
Abstract: We present a comprehensive analysis of the long-term photometric and spectroscopic monitoring campaign of the Type IIn supernova (SN) 2024kgi. The SN reaches a peak r -band absolute magnitude of −19.81 ± 0.06 mag and a bolometric luminosity of ∼2 × 10 43 erg s −1 . We observe a break in the lightcurve at day ∼312, after which the luminosity decline changes from t −1.0 to t −4.5 , likely due to the shock sweeping the dense circumstellar matter (CSM). We introduce a semi-analytical lightcurve modeling approach for CSM interaction in transients that accounts for variable diffusion time. We hence estimate a CSM mass of 2.3 4 − 1.6 + 11.8 M ⊙ , with a density profile of ρ csm ∝ r −2.74 , indicating progressively increasing mass loss toward the SN explosion. The ejecta signatures emerge as broad H, He, and Ca ii triplet lines at day ∼80, much earlier than expected from a spherically symmetric CSM, suggesting asymmetry in the CSM. After the lightcurve break, the H lines exhibit a wavelength-dependent deficit in the red-wing flux, indicating new dust formation in the ejecta and/or in the postshock gas. We observe a near-IR (NIR) excess from day ∼40 onward. We attribute the early NIR excess before the lightcurve break solely to the NIR echo from preexisting dust, as there are no other indications for new dust formation. The late-time NIR excess likely has contributions from both the preexisting and newly formed dust. The steady increase in mass loss, slow CSM velocity, and asymmetric CSM favor a binary interaction-induced mass loss.
Source: The Astrophysical Journal
Authors: Naveen Dukiya, Kuntal Misra, Andrea Pastorello, Andrea Reguitti, Anjasha Gangopadhyay, Aravind P. Ravi, Brian Hsu, Noah Franz, David J. Sand, Nathan Smith, Jennifer E. Andrews, Moira Andrews, K. Azalee Bostroem, Collin Christy, Monalisa Dubey, Joseph R. Farah, Archana Gupta, Estefania Padilla Gonzalez, Emily Hoang, D. Andrew Howell, Curtis McCully, Darshana Mehta, Megan Newsome, Jeniveve Pearson, Nicolás Meza Retamal, Jeonghee Rho, Manisha Shrestha, Bhagya Subrayan, Giacomo Terreran, Lina Tomasella, Stefano Valenti, Giorgio Valerin, Kathryn Wynn
Institutions: M.J.P. Rohilkhand University, Aryabhatta Research Institute of Observational Sciences, Osservatorio Astronomico di Padova, National Institute for Astrophysics, Brera Astronomical Observatory, Stockholm University, University of California, Davis, University of Arizona, International Gemini Observatory, Las Cumbres Observatory Global Telescope Network, University of California, Santa Barbara, Johns Hopkins University, The University of Texas at Austin, Seoul National University, Search for Extraterrestrial Intelligence, Adler Planetarium
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7214101061