SN 2024hpj: A perspective on SN 2009ip-like events

TL;DR

The paper analyzes SN 2024hpj as a SN 2009ip-like event, revealing a triple-peaked light curve and spectra with narrow and broad line components consistent with strong CSM interaction. By assembling a sample of 24 SN 2009ip-like objects and grouping their light curves into four categories, the authors explore how CSM mass and geometry shape observables and how progenitor properties may vary. A rate analysis suggests progenitor masses around $25-31\,M_\odot$ (upper limit considerations acknowledged), implying a bias toward intermediate-to-high mass stars, often in binary systems that may undergo merger bursts. The study concludes that multiple channels, including binary interactions and mass loss via instabilities, likely drive the diversity of these transients, with future surveys like LSST expected to expand the sample and clarify the physical pathways.

Abstract

Supernovae (SNe) IIn are terminal explosions of massive stars that are surrounded by a dense circumstellar medium (CSM). Among SNe IIn, a notable subset is the SN 2009ip-like, which exhibits an initial, fainter peak attributed to stellar variability in the late evolutionary stages, followed by a brighter peak, interpreted as the SN explosion itself. In this context, we analysed the spectrophotometric evolution of SN 2024hpj, an object with a triple-peaked light curve and spectra typical of a SN IIn but with a complex line profile composed of broad P-Cygni features topped by narrow emissions. Comparing it with other SN 2009ip-like events in the literature, as well as with other unpublished objects (SNe 2019mry, 2022ytx, 2024uzf, and 2025csc), we identify star-forming regions as their preferred formation environment. On the other hand, the diversity of spectrophotometric features within the sample suggests that variations in CSM mass and distribution may influence the observed characteristics. We identify four sub-classes based on the luminosity and rapidity of the light curve evolution, which provides insights into possible differences in the progenitors, while a statistical analysis of their observed rate indicates progenitor masses around 25 - 31 solar masses or lower.

Figures (19)

• Figure 1: Light curve and spectra of SN 2009ip. Left: Annotated $R$ light curve showing the first outburst that marked the discovery of the transient in 2009, repeated outbursts during 2010 and 2011, and the main event in 2012. The inset zooms in on the latter, highlighting the presence of Events A and B. Different colours indicate the various light curve phases. Adapted from pasto_2009ip_2013. Data from maza_2009ip_2009smith_2009ip_2010foley_2009ip_2011mauerhan_2009ip_2013fraser_2009ip_2013pasto_2009ip_2013prieto_2009ip_2013margutti_2009ip_2014. Right: Selected spectra of SN 2009ip for key light curve phases (first discovery, repeated outbursts, Event A, and Event B). Numbers next to the spectra are computed from the epoch of first discovery. Data from pasto_2009ip_2013fraser_2009ip_2013.
• Figure 2: Finding chart for SN 2024hpj, observed on 27 May 2024 with NOT/ALFOSC in the $g,r$, and $i$ bands.
• Figure 3: Apparent light curve of SN 2024hpj in the $u,g,r,i,z,J,H,K,cyan,orange,w$, and $y$ bands. A rigid shift is applied for better visualisation. Top: Complete light curve covering the last $\sim3$ years. Bottom: Zoom-in on the Event A+B light curve. Dashed grey lines indicate the peaks of Events A and B, while grey arrows and open symbols indicate upper limits. Phases are calculated with respect to the epoch of the Event B maximum (MJD 60455).
• Figure 4: Spectral evolution of SN 2024hpj, with all spectra corrected for redshift and reddening. Numbers next to each spectrum indicate the rest-frame phase since the Event B maximum in the $g$ band. Dotted lines indicate the position of major emission lines.
• Figure 5: Pseudo-bolometric light curve of SN 2024hpj, constructed by integrating the $u$ to $K$ bands. The expected theoretical decay rate due to $^{56}$Co is also shown.