_version_ 1866918486855385088
author Ransome, Conor L.
Sand, David J.
Bostroem, K. Azalee
Ravi, Aravind P.
Subrayan, Bhagya M.
Andrews, Jennifer E.
Lane, Zachary G.
Dong, Yize
Nugent, Anya
Valenti, Stefano
Pearson, Jeniveve
Shrestha, Manisha
Tinyanont, Samaporn
Hsu, Brian
Andrews, Moira
Banhidi, Dominik
Biro, Imre Barna
Christy, Collin
Csanyi, Istvan
Farah, Joseph
Franz, Noah
Hoang, Emily T.
Hosseinzadeh, Griffin
Howell, D. Andrew
Janzen, Daryl
Jha, Saurabh W.
Kwok, Lindsey A.
Liu, Chang
Lundquist, Michael
Martas, Aidan
McCully, Curtis
Mehta, Darshana
Retamal, Nicolas E. Meza
Smith, Nathan
Szalai, Tamas
Vasylyev, Sergiy
Villar, V. Ashley
Wynn, Kathryn
author_facet Ransome, Conor L.
Sand, David J.
Bostroem, K. Azalee
Ravi, Aravind P.
Subrayan, Bhagya M.
Andrews, Jennifer E.
Lane, Zachary G.
Dong, Yize
Nugent, Anya
Valenti, Stefano
Pearson, Jeniveve
Shrestha, Manisha
Tinyanont, Samaporn
Hsu, Brian
Andrews, Moira
Banhidi, Dominik
Biro, Imre Barna
Christy, Collin
Csanyi, Istvan
Farah, Joseph
Franz, Noah
Hoang, Emily T.
Hosseinzadeh, Griffin
Howell, D. Andrew
Janzen, Daryl
Jha, Saurabh W.
Kwok, Lindsey A.
Liu, Chang
Lundquist, Michael
Martas, Aidan
McCully, Curtis
Mehta, Darshana
Retamal, Nicolas E. Meza
Smith, Nathan
Szalai, Tamas
Vasylyev, Sergiy
Villar, V. Ashley
Wynn, Kathryn
contents Interacting supernovae probe the twilight years of massive stars, exhibiting signatures of interaction between the supernova ejecta and surrounding material expelled from the progenitor. We present the peculiar interacting supernova, SN\,2025ngs in NGC5961 (37.8 Mpc). This transient toes the line between strongly interacting supernovae (type IIn) and type IIP supernovae. SN 2025ngs presents photometrically as a short-plateau supernova, with a plateau duration, t$_{\mathrm{PT}}^{}\approx70$ days. Interaction features subside within a week post-explosion, consistent with the growing number of flash supernovae, giving way to a short period where a typical IIP spectrum is exhibited. Towards the drop off the plateau, interaction features re-emerge, exhibiting complex H$α$ profiles throughout the rest of the transient evolution. We compare with models of early spectra, finding the abundances generally consistent with a supergiant progenitor with a high mass-loss rate (10$^{-3}$ M$_\odot$ yr$^{-1}$). Early, high-resolution spectra reveal a double-horned H$α$ profile, providing strong evidence for shock interaction with a proximate disk-like circumstellar medium. Spectroscopically, SN 2025ngs closely resembles the luminous SN 1998S, despite photometric differences, with SN 2025ngs having a relatively modest peak magnitude of $M_\mathrm{V}=-17.9$ mag, adding another member to the surprisingly diverse 98S-like group.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05380
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Eye of Sauron in SN 2025ngs: a Short-plateau Cousin of SN 1998S with Evidence for a Ring-like Circumstellar Medium
Ransome, Conor L.
Sand, David J.
Bostroem, K. Azalee
Ravi, Aravind P.
Subrayan, Bhagya M.
Andrews, Jennifer E.
Lane, Zachary G.
Dong, Yize
Nugent, Anya
Valenti, Stefano
Pearson, Jeniveve
Shrestha, Manisha
Tinyanont, Samaporn
Hsu, Brian
Andrews, Moira
Banhidi, Dominik
Biro, Imre Barna
Christy, Collin
Csanyi, Istvan
Farah, Joseph
Franz, Noah
Hoang, Emily T.
Hosseinzadeh, Griffin
Howell, D. Andrew
Janzen, Daryl
Jha, Saurabh W.
Kwok, Lindsey A.
Liu, Chang
Lundquist, Michael
Martas, Aidan
McCully, Curtis
Mehta, Darshana
Retamal, Nicolas E. Meza
Smith, Nathan
Szalai, Tamas
Vasylyev, Sergiy
Villar, V. Ashley
Wynn, Kathryn
Solar and Stellar Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
Interacting supernovae probe the twilight years of massive stars, exhibiting signatures of interaction between the supernova ejecta and surrounding material expelled from the progenitor. We present the peculiar interacting supernova, SN\,2025ngs in NGC5961 (37.8 Mpc). This transient toes the line between strongly interacting supernovae (type IIn) and type IIP supernovae. SN 2025ngs presents photometrically as a short-plateau supernova, with a plateau duration, t$_{\mathrm{PT}}^{}\approx70$ days. Interaction features subside within a week post-explosion, consistent with the growing number of flash supernovae, giving way to a short period where a typical IIP spectrum is exhibited. Towards the drop off the plateau, interaction features re-emerge, exhibiting complex H$α$ profiles throughout the rest of the transient evolution. We compare with models of early spectra, finding the abundances generally consistent with a supergiant progenitor with a high mass-loss rate (10$^{-3}$ M$_\odot$ yr$^{-1}$). Early, high-resolution spectra reveal a double-horned H$α$ profile, providing strong evidence for shock interaction with a proximate disk-like circumstellar medium. Spectroscopically, SN 2025ngs closely resembles the luminous SN 1998S, despite photometric differences, with SN 2025ngs having a relatively modest peak magnitude of $M_\mathrm{V}=-17.9$ mag, adding another member to the surprisingly diverse 98S-like group.
title The Eye of Sauron in SN 2025ngs: a Short-plateau Cousin of SN 1998S with Evidence for a Ring-like Circumstellar Medium
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.05380