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ASASSN-13dn: A Luminous and Double-Peaked Type II Supernova

E. Hueichapán, J. L. Prieto, R. Cartier, C. Contreras, M. Bersten, T. Moriya, C. Kochanek, B. J. Shappee

TL;DR

ASASSN-13dn is a luminous, hydrogen-rich Type II supernova exhibiting a prominent double-peaked light curve and strong evidence for ejecta–CSM interaction. Through multi-epoch photometry and 13 optical spectra, the study characterizes a secondary peak at ~+73 d, high early ejecta velocities (H$\alpha$ FWHM ~$>$10^4 km s$^{-1}$), and a late-time narrow P-Cygni component at ~1100 km s$^{-1}$. Bolometric modeling yields L$_{bol,max}$ ≈ $1.3\times10^{43}$ erg s$^{-1}$ and E$_{tot}$ > $4.5\times10^{49}$ erg, with a strict Ni-56 upper limit of ≲0.02 M$_{\odot}$, indicating non-radioactive powering in part. The authors argue that interaction with dense CSM shells likely ejected by an LBV-like progenitor, possibly complemented by magnetar energy or binary interaction, can explain the light-curve bumps and spectral evolution, highlighting ASASSN-13dn as a key example of LSNe II and the diversity of progenitor mass-loss processes in massive stars.

Abstract

We present observations of ASASSN-13dn, one of the first supernovae discovered by ASAS-SN, and a new member of the rare group of Luminous Type II Supernovae (LSNe II). It was discovered near maximum light, reaching an absolute magnitude of M$_{v}$ $\sim$ -19 mag, placing this object between normal luminosity type II SNe and superluminous SNe A detailed analysis of the photometric and spectroscopic data of ASASSN-13dn is performed. The spectra are characterized by broad lines, in particular the H$α$ lines where we measure expansion velocities ranging between 14000 - 6000 km s$^{-1}$ over the first 100 days. H$α$ dominates the nebular spectra, and we detect a narrow P-Cygni absorption within the broader emission line with an expansion velocity of 1100 km s$^{-1}$. Photometrically, its light curve shows a re-brightening of $\sim$ 0.6 mag in the $gri$ bands starting at 25$\pm$2 days after discovery, with a secondary peak at $\sim 73$d, followed by an abrupt and nearly linear decay of 0.09 mag d$^{-1}$ for the next 35 days. At later times, after a drop of 4 magnitudes from the second maximum, the light curves of ASASSN-13dn shows softer undulations from 125 to 175 days. We compare ASASSN-13dn with other LSNe II in the literature, finding no match to both light curve and spectroscopic properties. We discuss the main powering mechanism and suggest that interaction between the ejecta and a dense CSM produced by eruptions from an LBV-like progenitor could potentially explain the observations.

ASASSN-13dn: A Luminous and Double-Peaked Type II Supernova

TL;DR

ASASSN-13dn is a luminous, hydrogen-rich Type II supernova exhibiting a prominent double-peaked light curve and strong evidence for ejecta–CSM interaction. Through multi-epoch photometry and 13 optical spectra, the study characterizes a secondary peak at ~+73 d, high early ejecta velocities (H FWHM ~10^4 km s), and a late-time narrow P-Cygni component at ~1100 km s. Bolometric modeling yields L ≈ erg s and E > erg, with a strict Ni-56 upper limit of ≲0.02 M, indicating non-radioactive powering in part. The authors argue that interaction with dense CSM shells likely ejected by an LBV-like progenitor, possibly complemented by magnetar energy or binary interaction, can explain the light-curve bumps and spectral evolution, highlighting ASASSN-13dn as a key example of LSNe II and the diversity of progenitor mass-loss processes in massive stars.

Abstract

We present observations of ASASSN-13dn, one of the first supernovae discovered by ASAS-SN, and a new member of the rare group of Luminous Type II Supernovae (LSNe II). It was discovered near maximum light, reaching an absolute magnitude of M -19 mag, placing this object between normal luminosity type II SNe and superluminous SNe A detailed analysis of the photometric and spectroscopic data of ASASSN-13dn is performed. The spectra are characterized by broad lines, in particular the H lines where we measure expansion velocities ranging between 14000 - 6000 km s over the first 100 days. H dominates the nebular spectra, and we detect a narrow P-Cygni absorption within the broader emission line with an expansion velocity of 1100 km s. Photometrically, its light curve shows a re-brightening of 0.6 mag in the bands starting at 252 days after discovery, with a secondary peak at d, followed by an abrupt and nearly linear decay of 0.09 mag d for the next 35 days. At later times, after a drop of 4 magnitudes from the second maximum, the light curves of ASASSN-13dn shows softer undulations from 125 to 175 days. We compare ASASSN-13dn with other LSNe II in the literature, finding no match to both light curve and spectroscopic properties. We discuss the main powering mechanism and suggest that interaction between the ejecta and a dense CSM produced by eruptions from an LBV-like progenitor could potentially explain the observations.

Paper Structure

This paper contains 12 sections, 12 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Data
  3. Discovery and host galaxy
  4. Photometry
  5. Spectroscopy
  6. Analysis
  7. Light Curve
  8. Bolometric light curve
  9. Spectra
  10. H$\alpha$ evolution
  11. Discussion
  12. Summary and conclusions

Figures (12)

  • Figure 1: LCOGT $gri$ composite image of ASASSN-13dn.
  • Figure 2: ASASSN-13dn ligth curve. A secondary peak is observed at $\sim$ 73 days after the first detection. In the tail of the light curve, clear sign of ejecta-CSM interaction are seen in the wiggles. The decline slope after the secondary peak is faster than the slope after the first peak. The lines at the bottom mark the epochs where spectroscopic data are available. The vertical lines divide the light curve in the phases described in section \ref{['sec:LC']}
  • Figure 3: $g-r$ color evolution of ASASSN-13dn compared with LSNe II presented in Pessi2023. Despite the variety of light curve shapes, the colors are consistent between objects.
  • Figure 4: Comparison of the $r$-band absolute magnitude evolution with other LSNe II and SN 1987A. The phase is with respect to the maximum brightness. The bumps of ASASN-13dn are not seen in other objects. The adopted maximum light date in MJD, Distance (Mpc), and A$_V$ for each supernova are, respectively: SN 1987A$^{1}$: 49849.8, 0.05, 0.206 87A; SN 2008es: 54599.3 1013.2 0.032 miller09 SN 2013fc: 56530.8, 83.2, 2.914 2013fc; ASASSN-15no: 57235.5, 153.5, 0.045 15no; SN 2016gsd: 57662.5, 311.6, 0.254 2016gsd; ASASSN-18am: 58142.6, 140.5, 0.027 15nx; SN 2017cfo: 57838.0, 178.2, 0.066; SN 2017hbj: 58031.0, 75.0, 0.095; SN 2017hxz: 58070.0, 330.6, 0.128; SN 2018aql: 58206.0, 321.4, 0.052; SN 2018eph: 58342.0, 121.8, 0.066 Pessi2023. 1: Note that the phase reported for SN 1987A is relative to the explosion and not the maximum.
  • Figure 5: Bolometric light curve and best-fit parameters from the black-body fitting for ASASSN-13dn. The upper panel shows the bolometric and pseudo-bolometric light curve. The middle and bottom panels shows the effective temperature and blackbody radius derived from superbol.py, respectively. The increase at +40d might indicate an outward movement of the photosphere.
  • ...and 7 more figures