학술논문
Circumstellar interaction signatures in the low luminosity type II SN 2021gmj
Document Type
Working Paper
Author
Meza-Retamal, Nicolas; Dong, Yize; Bostroem, K. Azalee; Valenti, Stefano; Galbany, Lluis; Pearson, Jeniveve; Hosseinzadeh, Griffin; Andrews, Jennifer E.; Sand, David J.; Jencson, Jacob E.; Janzen, Daryl; Lundquist, Michael J.; Hoang, Emily T.; Wyatt, Samuel; Brown, Peter J.; Howell, D. Andrew; Newsome, Megan; Gonzalez, Estefania Padilla; Pellegrino, Craig; Terreran, Giacomo; Kouprianov, Vladimir; Hiramatsu, Daichi; Jha, Saurabh W.; Smith, Nathan; Haislip, Joshua; Reichart, Daniel E.; Shrestha, Manisha; Rosales-Ortega, F. Fabián
Source
Subject
Language
Abstract
We present comprehensive optical observations of SN~2021gmj, a Type II supernova (SN~II) discovered within a day of explosion by the Distance Less Than 40~Mpc (DLT40) survey. Follow-up observations show that SN~2021gmj is a low-luminosity SN~II (LL~SN~II), with a peak magnitude $M_V = -15.45$ and Fe~II velocity of $\sim 1800 \ \mathrm{km} \ \mathrm{s}^{-1}$ at 50 days past explosion. Using the expanding photosphere method, we derive a distance of $17.8^{+0.6}_{-0.4}$~Mpc. From the tail of the light curve we obtain a radioactive nickel mass of $0.014 \pm 0.001$ M$_{\odot}$. The presence of circumstellar material (CSM) is suggested by the early-time light curve, early spectra, and high-velocity H$\alpha$ in absorption. Analytical shock-cooling models of the light curve cannot reproduce the fast rise, supporting the idea that the early-time emission is partially powered by the interaction of the SN ejecta and CSM. The inferred low CSM mass of 0.025 M$_{\odot}$ in our hydrodynamic-modeling light curve analysis is also consistent with our spectroscopy. We observe a broad feature near 4600 \AA, which may be high-ionization lines of C, N, or/and He~II. This feature is reproduced by radiation-hydrodynamic simulations of red supergiants with extended atmospheres. Several LL~SNe~II show similar spectral features, implying that high-density material around the progenitor may be common among them.
Comment: Accepted version at ApJ
Comment: Accepted version at ApJ