We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of ⁵⁶Co for which we derive a mass of M(⁵⁶Co) = (2.8 0.1) 10⁻² M _⊙. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale t _γ = 53.9 1.30 days, but we find no statistical evidence for incomplete positron trapping in the SN ejecta. While our observations cannot constrain the exact masses of other radioactive isotopes synthesized in SN 2019ehk, we estimate a mass ratio limit of M(⁵⁷Co)/M(⁵⁶Co) ≤ 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, which is one of the favored progenitor scenarios in early-time studies of SN 2019ehk.

我们在爆炸后276-389天呈现富含钙的超新星（SN）SN 2019ehk的多波段哈勃太空望远镜成像。这些观测结果代表了迄今为止富含钙的瞬态的最新B波段至近红外光度测量，并为分析该观测SN类中物体的后期辐射强度演化提供了第一个机会。我们发现，SN 2019ehk的后期时间测辐射热光曲线可通过放射性衰变主要描述⁵⁶共同为我们所衍生的质量中号（⁵⁶ Co）的=（2.8 0.1）10 ^-2 中号 _⊙。此外，辐射热亮度的下降速率要求泄漏γ。γ射线的时间表牛逼 _γ = 53.91.30天，但我们发现了不完整的正电子在SN喷出物捕集没有统计证据。虽然我们的观察结果无法约束SN 2019ehk中合成的其他放射性同位素的确切质量，但我们估计质量比极限为M（⁵⁷ Co）/ M（⁵⁶ Co）≤0.030。此限制与低质量白矮星合并产生的爆炸性核合成相一致，这是SN 2019ehk早期研究中最受关注的祖先场景之一。