SN2019yvq不符合SN Ia爆炸模型
SN2019yvq Does Not Conform to SN Ia Explosion Models
摘要：
我们提出了新的光度和光谱观测SN 2019 yvq，一个Ia型超新星（SN Ia）表现出几个特殊的属性，包括过量的紫外线/光通量的天内爆炸，一个高的硅速度，和一个低的峰值光度。在第一次光的时间附近的测光对UV/光通量过量的快速上升施加了新的约束。在最大亮度后$+173$天的近红外光谱严格限制了H或He辐射的存在，有效地排除了爆炸时附近非简并恒星的存在。在最大光照后+128天和+150天获得的新光谱证实了SN 2019 yvq过渡到星云阶段时存在CaII $λ7300~$和持续的CaII NIR三重态发射。[OI] $λ6300~$电子发射的缺乏不利于两颗C/O白矮星（WD）的剧烈合并，但不能排除一颗C/O WD与一颗He WD的合并。我们比较我们的研究结果与几个模型在文献中假设解释早期通量过剩，包括双爆轰爆炸，$^{56}$镍混合到外部喷出物在点火过程中，和相互作用与H-和He-缺乏拱星材料。每个模型都可能能够解释早期的通量过剩和星云的[CaII]发射，但没有一个模型能够在不引入新的差异的情况下调和高光球速度与低峰值光度。
英文摘要：
We present new photometric and spectroscopic observations of SN 2019yvq, a Type Ia supernova (SN Ia) exhibiting several peculiar properties including an excess of UV/optical flux within days of explosion, a high SiII velocity, and a low peak luminosity. Photometry near the time of first light places new constraints on the rapid rise of the UV/optical flux excess. A near-infrared spectrum at $+173$ days after maximum light places strict limits on the presence of H or He emission, effectively excluding the presence of a nearby non-degenerate star at the time of explosion. New optical spectra, acquired at +128 and +150 days after maximum light, confirm the presence of CaII$λ7300~$Å and persistent CaII NIR triplet emission as SN 2019yvq transitions into the nebular phase. The lack of [OI]$λ6300~$Å emission disfavors the violent merger of two C/O white dwarfs (WDs) but the merger of a C/O WD with a He WD cannot be excluded. We compare our findings with several models in the literature postulated to explain the early flux excess including double-detonation explosions, $^{56}$Ni mixing into the outer ejecta during ignition, and interaction with H- and He-deficient circumstellar material. Each model may be able to explain both the early flux excess and the nebular [CaII] emission, but none of the models can reconcile the high photospheric velocities with the low peak luminosity without introducing new discrepancies.
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