The fastest stars in the Galaxy-猫眼课题宝

DOI：

10.21105/astro.2306.03914

发表时间：

2023-06

期刊：

The Open Journal of Astrophysics

影响因子：

通讯作者：

中科院分区：

文献类型：

作者：

K. El-Badry;K. Shen;V. Chandra;E. Bauer;J. Fuller;J. Strader;L. Chomiuk;R. Naidu;I. Caiazzo;Antonio C. Rodriguez;Pranav Nagarajan-;Natsuko Yamaguchi;Z. Vanderbosch;B. Roulston;J. Roestel;B. Gansicke;Jiwon Jesse Han;K. Burdge;A. Filippenko;T. Brink;W. Zheng

我们报道了对超高速白矮星(WD)的光谱搜索，这些超高速白矮星是Ia型超新星(SNE Ia)和相关热核爆炸的逃逸。候选者是从高切向速度和蓝色的Gaia数据中挑选出来的。我们发现了6颗新的逃跑星，其中包括4颗径向速度为&gt；1000，rm Km，S^-1，总空间速度为$1300，\rm Km，S^-1的恒星。这些人最有可能是来自双简并双星的幸存捐赠者，在这些双星中，另一个WD爆炸了。另外两个天体的最小速度较低，分别为600rm、Km、S，它们可能是通过不同的机制形成的，例如IAX超新星中的WD纯爆燃。这四颗最快的恒星比之前已知的“D$^6$恒星”更热、更小，它们的有效温度从$\sim$20,000到$\sim$130,000 K，半径$\sim 0.02-0.10，R_{\ODOT}$。其中三个大气层以碳为主，一个大气层以氦为主。两颗恒星的房车分别为-1694美元和-2285\rM，公里，S^-1}美元--这是迄今测量到的最快的系统恒星房车。它们的出生速度，SIM2200-2500，Rm Km，S^-1，暗示在前身双星中的两个WD都有质量。观测到的高速度表明，观测到的超高速WD群体的主要部分来自总质量显著超过钱德拉塞卡极限的双简并双星。然而，最近和最暗的两颗D6星的速度和质量最低，这表明观测选择效应有利于更稀有、更大质量的恒星。一大批较弱的低质量离家出走的人可能仍在等待发现。我们推断D$^6$恒星的出生率与SN Ia率是一致的。然而，出生率的限制很差，因为$D^6$恒星的亮度和寿命是不确定的。

We report a spectroscopic search for hypervelocity white dwarfs (WDs) that are runaways from Type Ia supernovae (SNe Ia) and related thermonuclear explosions. Candidates are selected from Gaia data with high tangential velocities and blue colors. We find six new runaways, including four stars with radial velocities (RVs) $>1000\,\rm km\,s^{-1}$ and total space velocities $\gtrsim 1300\,\rm km\,s^{-1}$. These are most likely the surviving donors from double-degenerate binaries in which the other WD exploded. The other two objects have lower minimum velocities, $\gtrsim 600\,\rm km\,s^{-1}$, and may have formed through a different mechanism, such as pure deflagration of a WD in a Type Iax supernova. The four fastest stars are hotter and smaller than the previously known"D$^6$ stars,"with effective temperatures ranging from $\sim$20,000 to $\sim$130,000 K and radii of $\sim 0.02-0.10\,R_{\odot}$. Three of these have carbon-dominated atmospheres, and one has a helium-dominated atmosphere. Two stars have RVs of $-1694$ and $-2285\rm \,km\,s^{-1}$ -- the fastest systemic stellar RVs ever measured. Their inferred birth velocities, $\sim 2200-2500\,\rm km\,s^{-1}$, imply that both WDs in the progenitor binary had masses $>1.0\,M_{\odot}$. The high observed velocities suggest that a dominant fraction of the observed hypervelocity WD population comes from double-degenerate binaries whose total mass significantly exceeds the Chandrasekhar limit. However, the two nearest and faintest D$^6$ stars have the lowest velocities and masses, suggesting that observational selection effects favor rarer, higher-mass stars. A significant population of fainter low-mass runaways may still await discovery. We infer a birth rate of D$^6$ stars that is consistent with the SN Ia rate. The birth rate is poorly constrained, however, because the luminosities and lifetimes of $\rm D^6$ stars are uncertain.

The fastest stars in the Galaxy

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