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Giant outbursts of clumpy material preceding Type II supernova 2024qiw

T. Nagao, H. Kuncarayakti, K. Maeda, S. Mattila, R. Kotak, T. Killestein, C. Humina, D. Steeghs, D. Jarvis

TL;DR

Massive stars exhibit poorly understood mass-loss episodes in the final decades before core collapse. By combining photometry, spectroscopy, and polarimetry of SN 2024qiw, the study demonstrates giant outbursts of clumpy circumstellar material with a high pre-SN mass-loss rate ($\gtrsim 10^{-2}$ M_sun yr$^{-1}$) and episodic ejecta–CSM interactions that produce two major rebrightenings. The inferred timings (~$5$–$12$ years and ~ $17$–$24$ years before explosion) and non-spherical CSM geometry challenge standard stellar evolution, suggesting LBV-like eruptions or other hydrogen-rich progenitors can undergo dramatic pre-SN mass loss without yielding a Type IIn event. This work implies substantial diversity in late-stage mass-loss processes and calls for revisions to massive-star evolution models to account for violent, clumpy, pre-explosion mass ejections.

Abstract

Observations of core-collapse supernovae suggest that some massive stars undergo intense mass loss shortly before explosion, but the underlying mechanisms remain unknown. Here we report evidence of giant outbursts of clumpy material from a massive star in the final decades before explosion. Photometric, spectroscopic, and polarimetric data of SN~2024qiw reveal a bumpy light curve, a broad H$α$ profile, and variable polarization, all consistent with interaction between SN ejecta and clumpy circumstellar material, implying a mass-loss rate of $\gtrsim 10^{-2}$ M$_\odot$ yr$^{-1}$. Taken together, the most likely explanation is multiple major eruptions, similar to those of Luminous Blue Variables (LBVs), but occurring shortly before explosion. This challenges standard stellar evolution theory by requiring either that LBVs explode terminally, or that other evolutionary phases produce eruptive episodes. In spite of very high pre-SN mass loss, the resulting SN is of Type~II, rather than Type IIn, highlighting diverse and previously unrecognized late-stage mass-loss processes.

Giant outbursts of clumpy material preceding Type II supernova 2024qiw

TL;DR

Massive stars exhibit poorly understood mass-loss episodes in the final decades before core collapse. By combining photometry, spectroscopy, and polarimetry of SN 2024qiw, the study demonstrates giant outbursts of clumpy circumstellar material with a high pre-SN mass-loss rate ( M_sun yr) and episodic ejecta–CSM interactions that produce two major rebrightenings. The inferred timings (~– years and ~ – years before explosion) and non-spherical CSM geometry challenge standard stellar evolution, suggesting LBV-like eruptions or other hydrogen-rich progenitors can undergo dramatic pre-SN mass loss without yielding a Type IIn event. This work implies substantial diversity in late-stage mass-loss processes and calls for revisions to massive-star evolution models to account for violent, clumpy, pre-explosion mass ejections.

Abstract

Observations of core-collapse supernovae suggest that some massive stars undergo intense mass loss shortly before explosion, but the underlying mechanisms remain unknown. Here we report evidence of giant outbursts of clumpy material from a massive star in the final decades before explosion. Photometric, spectroscopic, and polarimetric data of SN~2024qiw reveal a bumpy light curve, a broad H profile, and variable polarization, all consistent with interaction between SN ejecta and clumpy circumstellar material, implying a mass-loss rate of M yr. Taken together, the most likely explanation is multiple major eruptions, similar to those of Luminous Blue Variables (LBVs), but occurring shortly before explosion. This challenges standard stellar evolution theory by requiring either that LBVs explode terminally, or that other evolutionary phases produce eruptive episodes. In spite of very high pre-SN mass loss, the resulting SN is of Type~II, rather than Type IIn, highlighting diverse and previously unrecognized late-stage mass-loss processes.

Paper Structure

This paper contains 10 sections, 6 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Observational properties
  3. Discussion
  4. Discovery, explosion epoch, redshift, and extinction
  5. Observations and data reduction
  6. Photometry
  7. Spectroscopy
  8. Polarimetry
  9. Spectral comparison between SN 2024qiw and other Type II SNe
  10. Polarimetric properties of SN 2024qiw

Figures (6)

  • Figure 1: Photometry of SN 2024qiw. Top: optical LCs (colored points) compared with those of other SNe (gray points; plotted toward the right $y$-axis). The comparison data are from Singh2024Anderson2014Galbany2016Nagao2024Reynolds2025a. The black lines show $V$-band LCs from the CSM-interaction model of Moriya2013, assuming SN ejecta with $n=12$, $\delta=1$, $M_{\rm{ej}}=10$$M_{\odot}$, and $E_{\rm{ej}}=10^{51}$ erg, and a spherical CSM with $v_{\rm{w}}=100$ km s$^{-1}$ and $s=2$, and a convergent efficiency $\epsilon=0.5$. The lines correspond to mass-loss rates of $10^{-1}$ to $10^{-4}$$M_{\odot}$ yr$^{-1}$ (top to bottom). Bottom: the $c$-$o$ evolution compared with SN 2023ixf.
  • Figure 2: Spectral sequence of SN 2024qiw (top panel) and evolution of the H$\alpha$ and H$\beta$ line profiles (bottom panel). The continuum level is determined by the fluxes at the wavelength ranges from -20000 to -15000 km s$^{-1}$ and from 9000 to 11000 km s$^{-1}$. The phases are given relative to the explosion.
  • Figure 3: Schematic illustration of our interpretation of the observational properties of SN 2024qiw. The left and right panels correspond to the first and second rebrightenings, respectively, with the system viewed from above each bottom panel. The enhancement of the $-4000$km/s component in the H$\alpha$ profile during the first rebrightening indicates interaction with a major CSM clump on the near side of the SN ejecta, while the enhancement of the $+2000$ km/s component during the second rebrightening suggests interaction with another major clump on the far side. The dotted lines show the locations of the local photospheres produced by the CSM-clump interaction.
  • Figure 4: Spectral comparison between SNe 2024qiw and 2023ixf. The early spectra of SN 2023ixf (colored lines) are overplotted on the earliest (Phase +27) spectrum of SN 2024qiw (gray). The phases are given relative to the explosion.
  • Figure 5: Spectral comparison with other Type II SNe at three different phases. The data for the comparison SNe were taken from Singh2024Michel2025 for SN 2023ixf, Hamuy2001Leonard2002 for SN 1999em, Hosseinzadeh2022Nagao2024 for SN 2021yja, and Reynolds2025a for SN 2021irp, via the Weizmann Interactive Supernova Data Repository Yaron2012.
  • ...and 1 more figures