论文标题

超新星冒名顶替者的蓝色超级祖先在〜2019Krl

The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl

论文作者

Andrews, Jennifer E., Jencson, Jacob E., Van Dyk, Schuyler D., Neustadt, Jack M. M., Smith, Nathan, Sand, David J., Kreckel, K., Kochanek, C. S., Valenti, S., Strader, Jay, Bersten, M. C., Blanc, Guillermo A., Bostroem, K. Azalee, Brink, Thomas G., Emsellem, Eric, Filippenko, Alexei V., Folatelli, Gastón, Kasliwal, Mansi M., Masci, Frank J., McElroy, Rebecca, Milisavljevic, Dan, Santoro, Francesco, Szalai, Tamás

论文摘要

广泛的存档\ TextIt {Hubble Space望远镜},\ TextIt {Spitzer Space望远镜}以及M74中最新中间luminosie Transient的大型双筒望远镜成像,M74中的〜20KRLL,显示出明亮的光学光学和中帧的光学和中间的前胎恒星。虽然错过了事件的光峰,但在红外线中检测到峰值,绝对幅度为$ m_ {4.5 \,μ{\ rm m}} = -18.4 $ mag,导致我们推断出视觉波长的绝对幅度$ -13.5至$ -14.5 $ -14.5 $ 13.5至$ 14.5。前发现的光曲线表明在前16 \ yr上没有爆发。如果仅考虑到任何其他局部灭绝,则祖先的颜色,幅度和推断的温度最佳与13--14 m $ $ _ {\ sun} $黄色或蓝色的超级巨人(BSG)匹配,或者仅考虑前景灭绝或更热的恒星,或者更热的恒星。恒星的爆发光谱显示出强大的H $α$和[n〜 {\ sc ii}]发射,翅膀延伸至$ \ pm 2000 $ \,km \,s $^{ - 1} $。爆发后的频谱相当平坦且毫无特色,只有H $α$,\ ion {Na} {1} 〜D,[\ ion {Ca} {2}],而\ ion {Ca} {Ca} {2} {2} {2} {2}发射中的三重态。与许多以前的中间发光瞬变一样,在〜2019krl上表现出与发光蓝色变量(LBV)巨型喷发,SN〜2008类似事件和大规模明星合并的显着观察性相似性。但是,有关爆发前星的信息偏爱相对毫不掩饰的BSG或更熄灭的LBV,$ m> 20 $ \,m $ _ {\ sun} $可能会查看。

Extensive archival \textit{Hubble Space Telescope}, \textit{Spitzer Space Telescope}, and Large Binocular Telescope imaging of the recent intermediate-luminosity transient, AT~2019krl in M74, reveal a bright optical and mid-infrared progenitor star. While the optical peak of the event was missed, a peak was detected in the infrared with an absolute magnitude of $M_{4.5\,μ{\rm m}} = -18.4$ mag, leading us to infer a visual-wavelength peak absolute magnitude of $-$13.5 to $-$14.5. The pre-discovery light curve indicated no outbursts over the previous 16\,yr. The colors, magnitudes, and inferred temperatures of the progenitor best match a 13--14 M$_{\sun}$ yellow or blue supergiant (BSG), if only foreground extinction is taken into account, or a hotter and more massive star, if any additional local extinction is included. A pre-eruption spectrum of the star reveals strong H$α$ and [N~{\sc ii}] emission with wings extending to $\pm 2000$\,km\,s$^{-1}$. The post-eruption spectrum is fairly flat and featureless with only H$α$, \ion{Na}{1}~D, [\ion{Ca}{2}], and the \ion{Ca}{2} triplet in emission. As in many previous intermediate-luminosity transients, AT~2019krl shows remarkable observational similarities to luminous blue variable (LBV) giant eruptions, SN~2008S-like events, and massive-star mergers. However, the information about the pre-eruption star favors either a relatively unobscured BSG or a more extinguished LBV with $M > 20$\,M$_{\sun}$ likely viewed pole-on.

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