Logo image
Back
Late-Time HST UV Detections Reveal Eruptive Mass Loss and Circumstellar Interaction in a Quarter of Stripped-Envelope Supernovae
Preprint   Open access

Late-Time HST UV Detections Reveal Eruptive Mass Loss and Circumstellar Interaction in a Quarter of Stripped-Envelope Supernovae

C Fremling, S Covarrubias, J Sollerman, K De, T. X Chen, T. -W Chen, R Dekany, C Fransson, A Gal-Yam, S. L Groom, …
30 Mar 2026
DOI: https://doi.org/10.48550/arxiv.2603.29043
url
https://doi.org/10.48550/arXiv.2603.29043View
Preprint (Author's original)arXiv.org - Non-exclusive license to distribute,  Open

Abstract

Physics - High Energy Astrophysical Phenomena
We present HST WFC3/UVIS F275W near-UV imaging of 91stripped-envelope supernovae (SE SNe; Types IIb, Ib, Ic) from Snapshot program SNAP-16657, observed at phases of 270-1845 days (median 952 days) after first optical detection. We detect UV counterparts in 13 SE~SNe, of which 6 are classified as secure and 7 as ambiguous after comparison to nearby Hii regions, interpreting the secure sources as signatures of interaction with circumstellar material (CSM). Independent WISE W1/W2 light curves show$>300$day mid-IR excesses in two of the secure UV sources, corroborating the interaction interpretation, and reveal two additional IR-only candidates without UV counterparts, indicating dust-obscured interaction episodes missed by the UV survey. A forward-modeling MCMC analysis using a physics-based CSM interaction model with three free parameters, the interaction fraction$f_\mathrm{CSM}$ , shell mass$M_\mathrm{CSM}$ , and thickness fraction$f_\mathrm{thick}$ , yields$f_\mathrm{CSM} = 0.23^{+0.17}_{-0.09}$ ,$M_\mathrm{CSM} \approx 0.013~M_\odot$ , and$f_\mathrm{thick} \approx 0.07$ . The inferred thin-shell geometry implies an ejection duration of$\sim$ 6 yr for an outflow velocity of$300$km s $^{-1}$ , two to three orders of magnitude shorter than the thermal timescale of stable Roche-lobe overflow. This result disfavors steady binary mass transfer as the origin of the detected CSM and instead points to eruptive pre-supernova mass ejection in the final years before core collapse, either from wave-driven outbursts or from mass transfer triggered by late-stage progenitor re-expansion.

Metrics

1 Record Views

Details

Logo image