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arXiv 1507.06347astro-ph.SRastro-ph.GAastro-ph.HE
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第谷超新星爆发中心的新确定及其对前伴星的启示

Newly Determined Explosion Center of Tycho's Supernova and the Implications for Proposed Ex-Companion Stars of the Progenitor

Zhichao Xue, Bradley E. Schaefer

摘要:

“G星”位于第谷SN 1572超新星遗迹的中心附近,被认为是爆炸的白矮星的前伴星,因此指出其前身就像是一颗复发的新星。这一主张一直是有争议的,但一直没有可靠的证据或反证。在此之前,没有人认真地讨论过1572年爆炸的确切地点。现在我们用两种截然不同的方法来精确测量超新星的位置。我们的第一种方法是使用1572年超新星和附近明亮恒星之间的42个测量角距离,单个测量值为84弧秒,所有测量值的1- $σ$误差半径为39弧秒(包括系统不确定性)。我们的第二种方法是使用一个详细而现实的膨胀模型,在残骸边缘周围的19个位置,在那里,扫起的物质已经测量了密度,我们用卡方拟合来确定膨胀的中心,以测量19个半径和速度。该方法的1- $σ$误差半径为7.5弧秒。这两种测量都从几何中心有很大的偏移,并且两者都非常接近,证明两者都没有任何显著的系统误差。我们对1572年爆炸地点的最终组合位置是J2000 $α$ = 0 h 25 m 15.36 s,$δ=64^{\circ} 8' 40.2"$,具有7.3弧秒的1-sigma不确定性。星形G在8.2- $σ$置信水平下被拒绝。我们的新位置主要位于以前寻找前伴星的区域之外。

英文摘要:

`Star G', near the center of the supernova remnant of Tycho's SN1572, has been claimed to be the ex-companion star of the exploding white dwarf, thus pointing to the progenitor being like a recurrent nova. This claim has been controversial, but there have been no confident proofs or disproofs. Previously, no has seriously addressed the question as to the exact explosion site in 1572. We now provide accurate measures of the supernova position by two radically different methods. Our first method is to use the 42 measured angular distances between the supernova in 1572 and bright nearby stars, with individual measures being as good as 84 arc-seconds, and all resulting in a position with a 1-$σ$ error radius of 39 arc-seconds (including systematic uncertainties). Our second method is to use a detailed and realistic expansion model for 19 positions around the edge of the remnant, where the swept-up material has measured densities, and we determine the center of expansion with a chi-square fit to the 19 measured radii and velocities. This method has a 1-$σ$ error radius of 7.5 arc-seconds. Both measures are substantially offset from the geometric center, and both agree closely, proving that neither has any significant systematic errors. Our final combined position for the site of the 1572 explosion is J2000 $α$=0h 25m 15.36s, $δ=64^{\circ} 8' 40.2"$, with a 7.3 arc-second 1-sigma uncertainty. Star G is rejected at the 8.2-$σ$ confidence level. Our new position lies mostly outside the region previously searched for ex-companion stars.

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