A Galactic-scale gas wave in the Solar Neighborhood
João Alves, Catherine Zucker, Alyssa A. Goodman, Joshua S. Speagle, Stefan Meingast, Thomas Robitaille, Douglas P. Finkbeiner, Edward F. Schlafly, Gregory M. Green
For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based on a peculiarity known as the Gould's Belt, an expanding ring of young stars, gas, and dust, tilted about 20$^\circ$ to the Galactic plane. Still, the physical relation between local gas clouds has remained practically unknown because the distance accuracy to clouds is of the same order or larger than their sizes. With the advent of large photometric surveys and the Gaia satellite astrometric survey this situation has changed. Here we report the 3-D structure of all local cloud complexes. We find a narrow and coherent 2.7 kpc arrangement of dense gas in the Solar neighborhood that contains many of the clouds thought to be associated with the Gould Belt. This finding is inconsistent with the notion that these clouds are part of a ring, disputing the Gould Belt model. The new structure comprises the majority of nearby star-forming regions, has an aspect ratio of about 1:20, and contains about 3 million solar masses of gas. Remarkably, the new structure appears to be undulating and its 3-D distribution is well described by a damped sinusoidal wave on the plane of the Milky Way, with an average period of about 2 kpc and a maximum amplitude of about 160 pc. Our results represent a first step in the revision of the local gas distribution and Galactic structure and offer a new, broader context to studies on the transformation of molecular gas into stars.
Fluorine in the Solar neighborhood: No evidence for the neutrino process
渐近巨星分支恒星是已知的生产“宇宙”氟,但它是不确定的,这些恒星是否是氟在太阳附近的主要生产者,或者如果任何其他建议的形成网站,II型超新星和/或沃尔夫-拉叶星,是更重要的。最近的文章提出了渐近巨星分支恒星以及II型超新星作为太阳附近氟的主要来源。在本文中,我们着手确定附近的49个样本中的氟丰度,明亮的K-巨星,我们以前已经确定了恒星参数以及α丰度均匀的光学高分辨率光谱。氟丰度由用分光计Phoenix观察到的2.3 $μ$ m HF分子线确定。我们将氟的丰度与主要产生于II型超新星的α元素的丰度进行比较,发现氟和α元素并不同步演化,排除了II型超新星是太阳系附近氟的主要生产者。此外,我们还发现了氟相对于氧的次级行为,这是另一个证据,反对II型超新星在太阳附近氟的产生中发挥重要作用。氟的这种次级行为将对其他两个建议的生产地点的恒星模型提出新的限制:渐近巨星分支星和沃尔夫-拉叶星。
Galactic chemical evolution (GCE), solar analogues or twins, and peculiarities of the solar composition with respect to the twins are inextricably related. We examine GCE parameters from the literature and present newly derived values using a quadratic fit that gives zero for a Solar age (i.e., 4.6 Gyr). We show how the GCE parameters may be used not only to "correct" abundances to the solar age, but to predict relative elemental abundances as a function of age. We address the question of whether the solar abundances are depleted in refractories and enhanced in volatiles and find that the answ…
Extended stellar systems in the solar neighborhood. IV. Meingast 1: the most massive stellar stream in the solar neighborhood
附近的恒星流携带着关于银河系恒星系统动力学演化和破裂、盘内质量分布的独特信息,为行星形成和演化研究提供了独特的目标。我们重新审视了Meingast等人(2019)发现的流,使用Gaia DR2数据和机器学习方法搜索新成员。我们使用一类支持向量机的装袋分类器进行搜索的新的流成员的位置和适当的运动。我们使用可变的预测频率,从众多的分类器来估计流成员资格标准,我们使用它来选择高保真源。我们使用HR图和笛卡尔速度分布作为测试和验证工具。我们发现了大约2000个高保真的流成员,或者比以前已知的多一个数量级,揭示了整个恒星质量谱中的流人口,从B星到M星,包括白矮星。我们发现,除了稍微更贫金属,流的HRD是无法区分的,从昴星团。对于我们最完整的质量范围,$\sim$ 0.2 M $_\odot$ $ < $ M $ < $ $\sim$ 4 M $_\odot$,我们发现一个正常的IMF,使我们能够估计流的总质量约为2000 M $_\odot$,使这个相对年轻的流迄今为止已知的最大质量。此外,我们确定了几个白矮星作为潜在的流成员。附近的Meingast 1流,由于其丰富,年龄和距离,是一个新的基本实验室恒星和行星形成和演化研究的研究不足的重力无约束恒星形成模式。我们还证明了单类支持向量机可以有效地用于揭示附近恒星系统的全部恒星星族与盖亚数据。
We introduce a novel non-parametric method to find solar neighborhood analogs (SNAs) in extragalactic IFS surveys. The main ansatz is that the physical properties of the solar neighborhood (SN) should be encoded in its optical stellar spectrum. We assume that our best estimate of such spectrum is the one extracted from the analysis performed by the Code for Stellar properties Heuristic Assignment (\textsc{CoSHA}) from the MaStar stellar library. It follows that finding SNAs in other galaxies consist in matching, in a $χ^2$ sense, the SN reference spectrum across the optical extent of the obser…
The stellar kinematics of the Galactic disk are main factors for constraining disk formation and evolution processes in the Milky Way (MW) Galaxy. In this paper we investigate a statistical relation between stellar Mass, Age and Velocity Dispersion for stars in the Solar neighborhood. Age-Velocity dispersion relations (AVR), with their applications, have been studied in details before. But their correlation with mass was mostly neglected. To investigate this relation, we use the proper motion data of more than 113035 stars in the Galactic disk (with Solar distances less than 150 parsecs) provi…
CWISEP J193518.59$-$154620.3: An Extremely Cold Brown Dwarf in the Solar Neighborhood Discovered with CatWISE
我们在CatWISE目录中发现了一颗极冷的、位于太阳附近的褐矮星(Eisenhartt等人,正在编写中)。斯皮策望远镜的光度跟踪显示,这颗天体CWISEP J193518.59-154620.3的ch 1 $-$ ch 2 = 3.24 $\,\pm\,$ 0.31等,使其成为已知最红的棕矮星之一。使用斯皮策光度法和Kirkpatrick等人(2019)的多项式关系,我们估计了$\sim$ 270- 360 K范围内的有效温度,以及5.6 $-$ 10.9 pc范围内的距离估计。我们结合了WISE、NEOWISE和斯皮策的数据,测量了$μ_α\cos δ= 337\pm69$ mas yr $^{-1}$、$μ_δ= -50\pm97$ mas yr $^{-1}$的自行,这意味着在7 $-$ 22 km s $^{-1}$范围内有一个相对较低的切向速度。
The spiral structure in the Solar neighborhood is an important issue in astronomy. In the past few years, there is significant progress in observation. The distances for a large number of good spiral tracers, i.e. giant molecular clouds, high-mass star-formation region masers, HII regions, O-type stars and young open clusters, have been accurately estimated, making it possible to depict the detailed properties of nearby spiral arms. In this work, we first give an overview about the research status for the Galaxy's spiral structure based on different types of tracers. Then the objects with dist…
We report the discovery of a young (only 30-40\,Myr) snake-like structure (dubbed a stellar "snake") in the solar neighborhood from {\it Gaia} DR2. The average distance of this structure is about 310\,pc from us. Both the length and width are over 200\,pc, but the thickness is only about 80\,pc. The "snake" has one tail and two dissolving cores, which can be clearly distinguished in the 6D phase space. The whole structure includes thousands of members with a total mass of larger than 2000\,$M_{\odot}$ in an uniform population. The population is so young that it can not be well explained with t…
With the calculated guiding center radius $R_{guiding}$ and birth radius $R_{birth}$, we investigate the role of radial migration on the description of lithium evolution in the Galactic disk based on the upper envelope of the A(Li) vs. [Fe/H] diagram. Using migration distances, we find that stars in the solar neighborhood are born at different locations in the galactic disk, and cannot all be explained by models of chemical evolution in the solar neighborhood. It is found that the upper envelope of the A(Li) vs. [Fe/H] diagram varies significantly with $R_{birth}$, which explains the decrease …
Moving Groups in the Solar Neighborhood with Gaia, APOGEE, GALAH, and LAMOST: Dynamical Effects Gather Gas and the Ensuing Star Formation Plays an Important Role in Shaping the Stellar Velocity Distributions
Are supernovae driving turbulence in the solar neighborhood?
Université Paris-Saclay(巴黎萨克雷大学);Université Paris Cité(巴黎西岱大学);CEA(法国原子能和替代能源委员会);CNRS(法国国家科学研究中心);University of Vienna(维也纳大学);ENS de Lyon(里昂高等师范学校);Universite Claude Bernard Lyon 1(里昂第一大学);Universität Heidelberg(海德堡大学);Laboratoire de Physique de l’Ecole Normale Supérieure(巴黎高等师范学院物理实验室);ENS(巴黎高等师范学院);Université PSL(巴黎文理研究大学);Sorbonne Université(索邦大学);Observatoire de Paris(巴黎天文台);INAF - Istituto di Astrofisica e Planetologia Spaziali(意大利国家天体物理研究所);Università di Roma Tor Vergata(罗马托尔维加塔大学)
Fluorine in the Solar Neighborhood: Chemical Evolution Models
根据太阳附近恒星氟丰度的新观测数据,本文提出了检验不同氟核合成处方的化学演化模型,目的是最好地拟合与[F/O] vs. [O/H]和[F/Fe] vs. [Fe/H]丰度比有关的新数据。采用的化学演化模型有:i)经典的“两次落入”模型,它遵循晕厚盘和薄盘相的化学演化,ii)和仅针对薄盘演化设计的“一次落入”模型。我们测试了不同核合成产额来源的预测氟丰度比的影响:AGB星,沃尔夫-拉叶星,II型和Ia型超新星,新星。我们发现氟的产生主要是由AGB星主导的,但需要Wolf-Rayet星才能用我们的化学演化模型再现Jönsson et al.(2017 a)在太阳附近观测数据的趋势。特别地,对于“两次入流”和“一次入流”情况的最佳模型都需要将Meynet和Arnould(2000)给出的Wolf-Rayet产率增加两倍。我们还表明,新星,即使他们的产量仍然是不确定的,可以帮助更好地再现F在[F/O]与[O/H]关系的二级行为。包含沃尔夫-拉叶星的氟生产似乎是复制Jönsson等人在太阳附近观察到的[F/O]与[O/H]的必要条件。此外,新星的列入有助于基本上再现所观察到的氟的二次行为。
Is there a left-handed magnetic field in the solar neighborhood? Exploring helical magnetic fields in the interstellar medium through dust polarization power spectra
Stellar Stream Candidates in the Solar Neighborhood Found in the LAMOST DR3 and TGAS
我们将LAMOST DR 3与Gaia DR 1 TGAS目录进行了交叉匹配,并获得了166,827颗具有可靠运动学的恒星样本。基于小波变换的技术被施加到检测显着的超密度在速度空间中的五个子样本划分的空间位置。总共发现了16颗运动学非常相似的恒星。其中,四个是新的流候选,其余的是先前已知的组。本地样品的U-V速度分布和金属丰度分布都显示出武仙座结构和Hyades-Pleiades结构之间的明显差距。这些峰的U-V位置随着空间位置而移动。在描述了我们的分析之后,我们推测了我们的候选流的可能起源。
We present a catalog of unbound stellar pairs, within 100 pc of the Sun, that are undergoing close, hyperbolic, encounters. The data are drawn from the GAIA EDR3 catalogue, and the limiting factors are errors in the radial distance and unknown velocities along the line of sight. Such stellar pairs have been suggested (Hansen & Zuckerman 2021) to be possible events associated with the migration of technological civilisations between stars. As such, this sample may represent a finite set of targets for a SETI search based on this hypothesis. Our catalog contains a total of 132 close passage even…
We present the results of a density-based clustering analysis of the 6-dimensional XYZ Galactic positions and UVW space velocities of nearby ($\leq$ 200 pc) Gaia EDR3 stars with radial velocities using HDBSCAN, in opposition to previous studies that only included positions and tangential velocities. Among the 241 recovered clusters, we identify more than 50 known associations, 32 new candidate stellar streams aged 100 Myr-3 Gyr, 9 extensions of known Theia groups uncovered by Kounkel & Covey (2019), and 8 newly recognized coronae around nearby open clusters. Three confirmed exoplanet-hosting s…