标题： 2019yvr型 Ib 超新星爆炸前2.6年的一个寒冷且膨胀的前身星候选者 显示英文标题

标题： A Cool and Inflated Progenitor Candidate for the Type Ib Supernova 2019yvr at 2.6 Years Before Explosion

摘要： 我们展示了哈勃空间望远镜对SN 2019yvr在爆发前的对应体的成像，该对应体在SN Ib爆发前2.6年被观测到。 与爆发后的Gemini-S/GSAOI图像对齐，我们证明存在一个单一的源，其与SN 2019yvr的前身星系统一致，这是继iPTF13bvn之后第二个SN Ib前身星候选体。 我们还分析了爆发前的Spitzer/IRAC成像，但在SN位置没有检测到任何对应体。 SN 2019yvr具有显著的红化，通过将其光谱和测光与其它红化较少的SN Ib进行比较，我们得出SN 2019yvr的值为$E(B-V)=0.51\substack{+0.27\\-0.16}$ mag。 对爆发前源的测光进行尘埃红化校正后，我们确定该源与一个$\log(L/L_{\odot}) = 5.3 \pm 0.2$ 和 $T_{\mathrm{eff}} = 6800\substack{+400\\-200}$ K的恒星一致。 这种相对较低的光球温度意味着半径为320$\substack{+30\\-50} R_{\odot}$，远大于具有微量氢的SN Ib前身星的预期，但与之前识别的SN IIb前身星系统一致。 该系统的测光也与经历共同包层演化的双星模型一致，导致主星的氢包层质量大部分耗尽，但似乎与SN 2019yvr的SN Ib分类相矛盾。 SN 2019yvr在晚期（$>$150天）的光谱和成像中表现出强的星周相互作用的特征，因此我们考虑爆发性质量损失和共同包层演化情景，这些情景可以解释SN Ib光谱类别、爆发前对应体和致密的星周物质。 我们还假设 apparent inflation 可能是由在主星周围的扩展低密度包层或星周物质中形成的准光球引起的。 显示英文摘要

摘要： We present Hubble Space Telescope imaging of a pre-explosion counterpart to SN 2019yvr obtained 2.6 years before its explosion as a type Ib supernova (SN Ib). Aligning to a post-explosion Gemini-S/GSAOI image, we demonstrate that there is a single source consistent with being the SN 2019yvr progenitor system, the second SN Ib progenitor candidate after iPTF13bvn. We also analyzed pre-explosion Spitzer/IRAC imaging, but we do not detect any counterparts at the SN location. SN 2019yvr was highly reddened, and comparing its spectra and photometry to those of other, less extinguished SNe Ib we derive $E(B-V)=0.51\substack{+0.27\\-0.16}$ mag for SN 2019yvr. Correcting photometry of the pre-explosion source for dust reddening, we determine that this source is consistent with a $\log(L/L_{\odot}) = 5.3 \pm 0.2$ and $T_{\mathrm{eff}} = 6800\substack{+400\\-200}$ K star. This relatively cool photospheric temperature implies a radius of 320$\substack{+30\\-50} R_{\odot}$, much larger than expectations for SN Ib progenitor stars with trace amounts of hydrogen but in agreement with previously identified SN IIb progenitor systems. The photometry of the system is also consistent with binary star models that undergo common envelope evolution, leading to a primary star hydrogen envelope mass that is mostly depleted but seemingly in conflict with the SN Ib classification of SN 2019yvr. SN 2019yvr had signatures of strong circumstellar interaction in late-time ($>$150 day) spectra and imaging, and so we consider eruptive mass loss and common envelope evolution scenarios that explain the SN Ib spectroscopic class, pre-explosion counterpart, and dense circumstellar material. We also hypothesize that the apparent inflation could be caused by a quasi-photosphere formed in an extended, low-density envelope or circumstellar matter around the primary star.