Volume 639, July 2020
|Number of page(s)||17|
|Published online||22 July 2020|
The Carnegie Supernova Project II
Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
2 School of Physics, O’Brien Centre for Science North, University College Dublin, Belfield, Dublin 4, Ireland
3 Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Høegh-Guldbergs Gade 6B, 8000 Aarhus C, Denmark
4 The George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 877843, USA
5 Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
6 Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile
7 Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain
8 Departamento de Física Teórica y del Cosmos, Universidad de Granada, 18071 Granada, Spain
9 Núcleo de Astronomía de la Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
10 Millennium Institute of Astrophysics, Santiago, Chile
11 Department of Physics, Florida State University, Tallahassee, FL 32306, USA
12 Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks, Rm 100, Norman, OK 73019-2061, USA
13 Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101, USA
14 National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
15 School of Physics and Astronomy, Faculty of Science, Monash University, Clayton, VIC 3800, Australia
16 INAF – Osservatorio Astronomico di Capodimonte, Salita Moiarello 16, Napoli, Italy
17 Università degli studi di Catania, Dip. di Fisica e Astronomia “E. Majorana”, Via Santa Sofia 64, 95123 Catania, Italy
18 INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
19 Laboratori Nazionali del Sud-INFN, Via Santa Sofia 62, 95123 Catania, Italy
20 SOAR Telescope, La Serena, 1700000, Chile
Accepted: 15 May 2020
We present multiwavelength observations of two gap transients that were followed by the Carnegie Supernova Project-II. The observations are supplemented with data obtained by a number of different programs. Here in the first of two papers, we focus on the intermediate-luminosity red transient (ILRT) designated SNhunt120, while in a companion paper we examine the luminous red novae AT 2014ej. Our data set for SNhunt120 consists of an early optical discovery, estimated to be within three days after outburst, the subsequent optical and near-infrared broadband followup extending over a period of about two months, two visual and two near-infrared wavelength spectra, and Spitzer Space Telescope observations extending from early (+28 d) to late (+1155 d) phases. SNhunt120 resembles other ILRTs such as NGC 300-2008-OT and SN 2008S, and like these other ILRTs, SNhunt120 exhibits prevalent mid-infrared emission at both early and late phases. From the comparison of SNhunt120 and other ILRTs to electron-capture supernova simulations, we find that the current models underestimate the explosion kinetic energy and thereby produce synthetic light curves that overestimate the luminosity. Finally, examination of pre-outburst Hubble Space Telescope images yields no progenitor detection.
Key words: supernovae: individual: SNhunt120 / supernovae: general
© ESO 2020
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