Issue |
A&A
Volume 662, June 2022
|
|
---|---|---|
Article Number | L10 | |
Number of page(s) | 13 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202243340 | |
Published online | 28 June 2022 |
Letter to the Editor
SN 2021foa, a transitional event between a Type IIn (SN 2009ip-like) and a Type Ibn supernova
1
Departamento de Ciencias Físicas – Universidad Andres Bello, Avda. República 252, 8320000 Santiago, Chile
e-mail: andreareguitti@gmail.com
2
Millennium Institute of Astrophysics, Nuncio Monsenor Sótero Sanz 100, Providencia, 8320000 Santiago, Chile
3
INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
4
School of Physics, O’Brien Centre for Science North, University College Dublin, Belfield, Dublin 4, Ireland
5
Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
6
Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 100084, PR China
7
Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans s/n, 08193 Barcelona, Spain
8
INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, Italy
9
Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vesilinnantie 5, 20014 Turku, Finland
10
Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
11
Turku Collegium for Science, Medicine and Technology, University of Turku, 20014 Turku, Finland
12
Department of Astronomy, AlbaNova University Center, Stockholm University, 10691 Stockholm, Sweden
13
The Oskar Klein Centre, AlbaNova, 10691 Stockholm, Sweden
14
Astrophysics Research Institute, Liverpool John Moores University, ic2, 146 Brownlow Hill, Liverpool L3 5RF, UK
15
Max-Planck Institut fur Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
16
Dipartimento di Fisica e Astronomia ‘G. Galilei’ – Universitá di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
Received:
16
February
2022
Accepted:
5
June
2022
We present photometric and spectroscopic data of the unusual interacting supernova (SN) 2021foa. It rose to an absolute magnitude peak of Mr = −18 mag in 20 days. The initial light curve decline shows some luminosity fluctuations before a long-lasting flattening. A faint source (Mr ∼ −14 mag) was detected in the weeks preceding the main event, showing a slowly rising luminosity trend. The r-band absolute light curve is very similar to those of SN 2009ip-like events, with a faint and shorter duration brightening (‘Event A’) followed by a much brighter peak (‘Event B’). The early spectra of SN 2021foa show a blue continuum with narrow (∼400 km s−1) H emission lines that, two weeks later, reveal a complex profile, with a narrow P Cygni on top of an intermediate-width (∼2700 km s−1) component. At +12 days, metal lines in emission appear and He I lines become very strong, with He I λ5876 reaching half of the Hα luminosity, much higher than in previous SN 2009ip-like objects. We propose that SN 2021foa is a transitional event between the H-rich SN 2009ip-like SNe and the He-rich Type Ibn SNe.
Key words: supernovae: general / supernovae: individual: SN 2021foa
© A. Reguitti et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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