We present a novel technique to study Type Ia supernovae (SNe Ia) by constraining surviving companions of historical extragalactic SN by combining archival photographic plates and Hubble Space Telescope(HST) imaging. We demonstrate this technique for Supernova 1972E, the nearest known SN Ia in 125 yr. Some models of SNe Ia describe a white dwarf with a non-degenerate companion that donates enough mass to trigger thermonuclear detonation. Hydrodynamic simulations and stellar evolution models show that these donor stars will survive the explosion, and show increased luminosity for at least a 1000 yr. Thus, late-time observations of the exact location of a supernova can constrain the presence of a surviving donor star and progenitor models. We find the explosion site of SN 1972E by analysing 17 digitized photographic plates taken with the European Southern Observatory 1-m Schmidt and 1 plate taken with the Cerro Tololo Inter-American Observatory 1.5-m telescope. Using the Gaia eDR3 catalogue to determine Supernova 1972E’s location yields: α = 13h39m52${_{.}^{\rm s}}$708 ± 0${_{.}^{\rm s}}$004 and δ = −31°40’9${_{.}^{\prime\prime}}$00 ± 0${_{.}^{\prime\prime}}$04 (ICRS). In 2005, HST/ACS imaged the host galaxy of SN 1972E with the F435W, F555W, and F814W filters covering the explosion site. The nearest detected source is offset by 3.0 times our positional precision, and is inconsistent with the colours expected of a surviving donor star. Thus, the limiting magnitude of the HST observation (F555W > 28 mag) rules out all He star companion models and the most luminous main-sequence companion model currently in the literature. The remaining main-sequence companion models could be tested with a 10 orbit HST exposure in the F606W filter.

中文翻译：

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过去的爆炸：约束 SN 1972E 的祖模型

我们提出了一种新技术来研究 Ia 型超新星 (SNe Ia)，通过结合档案照相板和哈勃太空望远镜 (HST) 成像来限制历史河外 SN 的幸存伴星。我们为超新星 1972E 演示了这种技术，它是 125 年内最近的已知 SN Ia。一些 SNe Ia 模型描述了一颗白矮星，它有一个未退化的伴星，它提供了足够的质量来触发热核爆炸。流体动力学模拟和恒星演化模型表明，这些供体恒星将在爆炸中幸存下来，并在至少 1000 年内显示出增加的光度。因此，对超新星确切位置的后期观测可以限制幸存的供体恒星和祖先模型的存在。我们通过分析欧洲南方天文台 1-m Schmidt 拍摄的 17 个数字化照相底片和 Cerro Tololo 美洲天文台 1.5-m 望远镜拍摄的 1 张数字化照相底片，找到了 SN 1972E 的爆炸地点。使用 Gaia eDR3 目录确定超新星 1972E 的位置得到： α = 13h39m52${_{.}^{\rm s}}$708 ± 0${_{.}^{\rm s}}$004 和 δ = -31 °40'9${_{.}^{\prime\prime}}$00 ± 0${_{.}^{\prime\prime}}$04 (ICRS)。2005 年，HST/ACS 用 F435W、F555W 和 F814W 滤光片覆盖了爆炸现场，对 SN 1972E 的宿主星系进行了成像。最近检测到的源偏移了我们位置精度的 3.0 倍，并且与幸存的供体恒星的预期颜色不一致。因此，HST 观测的极限幅度（F555W > 28 mag) 排除了所有 He 星伴星模型和目前文献中最发光的主序伴星模型。剩余的主序伴星模型可以在 F606W 滤波器中使用 10 轨道 HST 曝光进行测试。