Early Near-IR Echo and the Time-variable Mass-loss History of Type IIn SN 2024kgi

@article{dukiya2026early,
  title = {{Early Near-IR Echo and the Time-variable Mass-loss History of Type IIn SN 2024kgi}},
  author = {Naveen Dukiya and Kuntal Misra and Andrea Pastorello and Andrea Reguitti and Anjasha Gangopadhyay and Aravind P. Ravi and Brian Hsu and Noah Franz and David J. Sand and Nathan Smith and Jennifer E. Andrews and Moira Andrews and K. Azalee Bostroem and Collin Christy and Monalisa Dubey and Joseph R. Farah and Archana Gupta and Estefania Padilla Gonzalez and Emily Hoang and D. Andrew Howell and Curtis McCully and Darshana Mehta and Megan Newsome and Jeniveve Pearson and Nicolás Meza Retamal and Jeonghee Rho and Manisha Shrestha and Bhagya Subrayan and Giacomo Terreran and Lina Tomasella and Stefano Valenti and Giorgio Valerin and Kathryn Wynn},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aeac2b},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeac2b},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Early Near-IR Echo and the Time-variable Mass-loss History of Type IIn SN 2024kgi
AU  - Naveen Dukiya
AU  - Kuntal Misra
AU  - Andrea Pastorello
AU  - Andrea Reguitti
AU  - Anjasha Gangopadhyay
AU  - Aravind P. Ravi
AU  - Brian Hsu
AU  - Noah Franz
AU  - David J. Sand
AU  - Nathan Smith
AU  - Jennifer E. Andrews
AU  - Moira Andrews
AU  - K. Azalee Bostroem
AU  - Collin Christy
AU  - Monalisa Dubey
AU  - Joseph R. Farah
AU  - Archana Gupta
AU  - Estefania Padilla Gonzalez
AU  - Emily Hoang
AU  - D. Andrew Howell
AU  - Curtis McCully
AU  - Darshana Mehta
AU  - Megan Newsome
AU  - Jeniveve Pearson
AU  - Nicolás Meza Retamal
AU  - Jeonghee Rho
AU  - Manisha Shrestha
AU  - Bhagya Subrayan
AU  - Giacomo Terreran
AU  - Lina Tomasella
AU  - Stefano Valenti
AU  - Giorgio Valerin
AU  - Kathryn Wynn
PY  - 2026
DA  - 2026/10/27
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aeac2b
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aeac2b
AB  - 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.
SN  - 1538-4357
SN  - 0004-637X
ER  -