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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2511.03926 |
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| _version_ | 1866915608450301952 |
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| author | Dong, Yize Villar, V. Ashley Nugent, Anya Hosseinzadeh, Griffin Foley, Ryan J. Gall, Christa Gallegos-Garcia, Monica Ransome, Conor Sedgewick, Aidan Tsuna, Daichi Valenti, Stefano Abunemeh, Henna Andrews, Moira Auchettl, Katie Bostroem, K. Azalee Coulter, David A. de Boer, Thomas de Soto, Kaylee Farias, Diego A. Farah, Joseph Frostig, Danielle Gao, Hua Gagliano, Alex Hoang, Emily Howell, D. Andrew Hoogendam, Willem B. Huber, Mark E. Jones, David O. Lin, Chien-Cheng Lundquist, Michael McCully, Curtis Mehta, Darshana Piro, Anthony L. Ravi, Aravind P. Retamal, Nicolás Meza Rojas-Bravo, César Yadavalli, S. Karthik Wang, Qinan |
| author_facet | Dong, Yize Villar, V. Ashley Nugent, Anya Hosseinzadeh, Griffin Foley, Ryan J. Gall, Christa Gallegos-Garcia, Monica Ransome, Conor Sedgewick, Aidan Tsuna, Daichi Valenti, Stefano Abunemeh, Henna Andrews, Moira Auchettl, Katie Bostroem, K. Azalee Coulter, David A. de Boer, Thomas de Soto, Kaylee Farias, Diego A. Farah, Joseph Frostig, Danielle Gao, Hua Gagliano, Alex Hoang, Emily Howell, D. Andrew Hoogendam, Willem B. Huber, Mark E. Jones, David O. Lin, Chien-Cheng Lundquist, Michael McCully, Curtis Mehta, Darshana Piro, Anthony L. Ravi, Aravind P. Retamal, Nicolás Meza Rojas-Bravo, César Yadavalli, S. Karthik Wang, Qinan |
| contents | In this paper, we first present observations of SN~2024acyl, a normal Type Ibn supernova with a large projected offset ($\sim$35~kpc) from its host galaxy. The low star-formation rate measured at the explosion site raises the possibility that the progenitor of SN~2024acyl may not have been a massive star. We then examine, more broadly, the spectral diversity of Type Ibn supernovae around 20--35 days after peak brightness and identify two distinct groups: Group I, which shows bluer rest-frame optical color and narrower He~I emission lines; and Group II, which shows redder rest-frame optical color and broader He~I lines. Group~I also tends to show higher peak luminosities. The diversity we identify appears to be closely connected to the diversity observed around peak and to persist into late phases ($>80$ days after peak). Given its redder color and broader He~I lines, we classify SN~2024acyl as belonging to Group II. Based on the current dataset, we find no clear connection between this spectral diversity and either the host environments of Type Ibn SNe or their pre-explosion activity. The observed diversity in Type Ibn SNe likely reflects differences in circumstellar material properties and/or explosion energetics. These differences could result from a range of progenitor properties, such as different helium star mass, orbital period and companion type if they are in binary systems, and may indicate fundamentally diverse progenitors. Whether a continuous distribution exists between the two groups remains to be determined and will require further data to explore. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_03926 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spectral Diversity in Type Ibn Supernovae and the Large Host Offset of SN2024acyl Dong, Yize Villar, V. Ashley Nugent, Anya Hosseinzadeh, Griffin Foley, Ryan J. Gall, Christa Gallegos-Garcia, Monica Ransome, Conor Sedgewick, Aidan Tsuna, Daichi Valenti, Stefano Abunemeh, Henna Andrews, Moira Auchettl, Katie Bostroem, K. Azalee Coulter, David A. de Boer, Thomas de Soto, Kaylee Farias, Diego A. Farah, Joseph Frostig, Danielle Gao, Hua Gagliano, Alex Hoang, Emily Howell, D. Andrew Hoogendam, Willem B. Huber, Mark E. Jones, David O. Lin, Chien-Cheng Lundquist, Michael McCully, Curtis Mehta, Darshana Piro, Anthony L. Ravi, Aravind P. Retamal, Nicolás Meza Rojas-Bravo, César Yadavalli, S. Karthik Wang, Qinan High Energy Astrophysical Phenomena Solar and Stellar Astrophysics In this paper, we first present observations of SN~2024acyl, a normal Type Ibn supernova with a large projected offset ($\sim$35~kpc) from its host galaxy. The low star-formation rate measured at the explosion site raises the possibility that the progenitor of SN~2024acyl may not have been a massive star. We then examine, more broadly, the spectral diversity of Type Ibn supernovae around 20--35 days after peak brightness and identify two distinct groups: Group I, which shows bluer rest-frame optical color and narrower He~I emission lines; and Group II, which shows redder rest-frame optical color and broader He~I lines. Group~I also tends to show higher peak luminosities. The diversity we identify appears to be closely connected to the diversity observed around peak and to persist into late phases ($>80$ days after peak). Given its redder color and broader He~I lines, we classify SN~2024acyl as belonging to Group II. Based on the current dataset, we find no clear connection between this spectral diversity and either the host environments of Type Ibn SNe or their pre-explosion activity. The observed diversity in Type Ibn SNe likely reflects differences in circumstellar material properties and/or explosion energetics. These differences could result from a range of progenitor properties, such as different helium star mass, orbital period and companion type if they are in binary systems, and may indicate fundamentally diverse progenitors. Whether a continuous distribution exists between the two groups remains to be determined and will require further data to explore. |
| title | Spectral Diversity in Type Ibn Supernovae and the Large Host Offset of SN2024acyl |
| topic | High Energy Astrophysical Phenomena Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2511.03926 |