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Statistical properties of cold circumstellar envelops observed in NESS–NRO NESS-NRO观测到的冷星周包层的统计性质
Pub Date : 2021-08-01 DOI: 10.1017/S1743921323001783
K. Amada, S. Fukaya, H. Imai, P. Scicluna, N. Hirano, A. Trejo-Cruz, S. Zeegers, F. Kemper, S. Srinivasan, S. Wallström, T. Dharmawardena, H. Shinnaga
Abstract We conducted CO J=1→0 emission line observations for nearby AGB stars using the Nobeyama 45 m telescope. Comparing our results with those from CO J=3→2 observations with JCMT, the circumstellar envelopes observed in CO J=1→0 look more extended than J=3→2. Thus, we could trace the outer, cold parts of the envelopes. We also found four stars in which the CO/13CO ratio changes dramatically outward, but the change implies the effect of selective photodissociation by interstellar ultraviolet radiation, not the third dredge up in the stellar interior. We moreover found two unique stars with aspherical envelope morphology.
摘要利用Nobeyama 45 m望远镜对AGB附近的恒星进行了CO J=1→0发射线观测。将我们的结果与CO J=3→2用JCMT观测的结果进行比较,CO J=1→0观测到的星周包层看起来比J=3→2更延展。因此,我们可以追踪信封的外部,冷的部分。我们还发现有四颗恒星的CO/13CO比向外发生了巨大的变化,但这种变化意味着星际紫外线辐射选择性光解作用的影响,而不是第三颗恒星内部的影响。此外,我们还发现了两颗具有非球面包膜形态的独特恒星。
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引用次数: 1
Star formation history for the starburst dwarf galaxy in the Local Group, IC 10 本星系群ic10星暴矮星系的恒星形成历史
Pub Date : 2021-08-01 DOI: 10.1017/S1743921322004914
Mahtab Gholami, A. Javadi, J. V. van Loon, H. Khosroshahi, E. Saremi
Abstract IC 10 as a starburst dwarf galaxy in the Local Group (LG) has a large population of newly formed stars that are massive and intrinsically very bright in comparison with other LG galaxies. Using the Isaac Newton Telescope (INT) with the Wide Field Camera (WFC) in the i-band and V-band, we performed an optical monitoring survey to identify the most evolved asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) in this star-forming galaxy, which can be used to determine the star formation history (SFH). The E(B - V) as an effective factor for obtaining the precise magnitude of stars is measured for each star using a 2D dust map (SFD98) to obtain a total extinction for each star in both the i-band and V-band. We obtained the photometric catalog for 53579 stars within the area of 0.07 deg2 (13.5 kpc2), of which 762 stars are classified as variable candidates after removing the foreground stars and saturated ones from our catalog. To reconstruct the SFH for IC 10, we first identified 424 long-period variable (LPV) candidates within the area of two half-light radii (2r h ) from the center of the galaxy. We estimated the recent star formation rate (SFR) at ∼ 0.32 yr-1 for a constant metallicity Z = 0.0008, showing the galaxy is currently undergoing high levels of star formation. Also, a total stellar mass of is obtained within 2r h for that metallicity.
IC 10是本星系群(LG)中的一个星暴矮星系,拥有大量新形成的恒星,与其他LG星系相比,这些恒星质量大,本质上非常明亮。利用艾萨克·牛顿望远镜(INT)和宽视场相机(WFC)在i波段和v波段进行了光学监测调查,以确定该恒星形成星系中最进化的渐近巨星分支星(AGBs)和红超巨星(RSGs),可用于确定恒星形成历史(SFH)。利用二维尘埃图(SFD98)测量每颗恒星的E(B - V)作为精确星等的有效因子,得到每颗恒星在i波段和V波段的总消光。我们获得了0.07 deg2 (13.5 kpc2)范围内53579颗恒星的光度表,其中762颗恒星在剔除前景恒星和饱和恒星后被归为可变候选恒星。为了重建IC 10的SFH,我们首先在距离星系中心两个半光半径(2r小时)的区域内确定了424个长周期变量(LPV)候选者。我们估计最近的恒星形成速率(SFR)为~ 0.32年-1,金属丰度恒定Z = 0.0008,表明该星系目前正在经历高水平的恒星形成。同样,对于金属丰度,在2r小时内可以得到恒星的总质量。
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引用次数: 0
The JWST/NIRSpec GTO programme “The Physics of Galaxy Assembly: IFS observations of high-z galaxies” JWST/NIRSpec GTO项目“星系物理学汇编:高z星系的IFS观测”
Pub Date : 2021-08-01 DOI: 10.1017/S1743921323000200
Michele Perna
Abstract We present an overview of the project “The Physics of Galaxy Assembly: IFS observations of high-z galaxies”, a Guaranteed Time Observations (GTO) programme of the James Webb Space Telescope (JWST). It an ambitious project aimed at investigating the internal structure of distant galaxies with the NIRSpec integral field spectrograph (IFS), having allocated 273 hours of JWST prime time. The NIRSpec capability will provide us with spatially resolved spectroscopy in the 1-5 μm range of a sample of over forty galaxies and Active Galactic Nuclei in the redshift range 3 < z 9. IFS observations of individual galaxies will enable us to investigate in detail the most important physical processes driving galaxy evolution across the cosmic epoch. More in detail, the main specific objectives are: to trace the distribution of star formation, to map the resolved properties of the stellar populations, to trace the gas kinematics (i.e. velocity fields, velocity dispersion) and, hence, determine dynamical masses and also identify non-virial motions (outflow and inflows), and to map metallicity gradients and dust attenuation.
摘要:本文介绍了詹姆斯·韦伯太空望远镜(JWST)保证时间观测(GTO)项目“星系集合的物理学:高z星系的IFS观测”的概况。这是一个雄心勃勃的项目,旨在用NIRSpec积分场光谱仪(IFS)调查遥远星系的内部结构,已经分配了273小时的JWST黄金时间。NIRSpec能力将为我们提供超过40个星系和活动星系核样品在1-5 μm范围内的空间分辨光谱,红移范围为3 < z9。IFS对单个星系的观测将使我们能够详细研究推动整个宇宙时代星系演化的最重要的物理过程。更详细地说,主要的具体目标是:追踪恒星形成的分布,绘制恒星群的分辨属性,追踪气体运动学(即速度场,速度色散),从而确定动态质量,并确定非病毒运动(流出和流入),并绘制金属度梯度和尘埃衰减。
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引用次数: 1
To the dynamics of the two-body problem with variable masses in the presence of reactive forces 在反力作用下变质量两体问题的动力学
Pub Date : 2021-08-01 DOI: 10.1017/S174392132200360X
A. Ibraimova, M. Minglibayev
Abstract We studied the problem of two spherical celestial bodies in the general case when the masses of the bodies change non-isotropically at different rates in the presence of reactive forces. The problem was investigated by methods of perturbation theory based on aperiodic motion along a quasi-conic section, using the equation of perturbed motion in the form of Newton’s equations. The problem is described by the variables a, e, i, π, ω, λ, which are analogs of the corresponding Keplerian elements and the equations of motion in these variables are obtained. Averaging over the mean longitude, we obtained the evolution equations of the two-body problem with variable masses in the presence of reactive forces. The obtained evolution equations have the exact analytic integral ${a^3 e^4 = a^3_0 e^4_0} = {const}$ .
摘要研究了两个球形天体在反力作用下质量以不同速率非各向同性变化的一般情况下的问题。利用牛顿方程形式的微扰运动方程,利用基于准圆锥截面非周期运动的微扰理论方法对该问题进行了研究。用类似于相应的开普勒元素的变量a、e、i、π、ω、λ来描述问题,并得到了这些变量的运动方程。在平均经度上求平均值,得到了在反力作用下变质量两体问题的演化方程。得到的演化方程具有精确解析积分${a^3 e^4 = a^3_0 e^4_0} = {const}$。
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引用次数: 0
Effect of gas percentage during minor mergers on the star formation in galaxies 星系中小合并过程中气体百分比对恒星形成的影响
Pub Date : 2021-08-01 DOI: 10.1017/S1743921322004781
S. N. Hasan, Swetha Thakkalapally, P. Hasan
Abstract We study the effect of minor mergers on star formation using simulations. We use GADGET4 code which has both collisionless and hydrodynamical particles. Our goal is to establish a relation between gas percentage present in the galaxies and the star formation in the merged galaxy. We use 1:10 minor mergers and we run the isolated simulations with varying gas percentages in the primary galaxy. We observe that the gas particles convert into stars due to the impact of the minor merger. As the gas percentage increases in the primary disk of the galaxy, more number of stars are formed. We also observed that newly formed star particles settle down in the disk of the primary galaxy and increase the thickness of the disk. We also observe that the thickness of the stellar disk containing the old stars also increases due to the impact of the merger.
摘要本文通过模拟研究了小合并对恒星形成的影响。我们使用GADGET4代码,它既有无碰撞粒子,又有流体动力学粒子。我们的目标是建立星系中存在的气体百分比与合并星系中恒星形成之间的关系。我们使用1:10的小合并,我们用主星系中不同的气体百分比进行孤立的模拟。我们观察到,由于小型合并的影响,气体粒子转变为恒星。随着星系主盘中气体含量的增加,形成的恒星数量也随之增加。我们还观察到,新形成的恒星粒子沉降在主星系的圆盘中,并增加了圆盘的厚度。我们还观察到,由于合并的影响,包含老恒星的星盘的厚度也增加了。
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引用次数: 0
Colour gradients of low-redshift galaxies in the DESI Legacy Imaging Survey 低红移星系在DESI遗产成像调查中的颜色梯度
Pub Date : 2021-08-01 DOI: 10.1093/mnras/stac3327
L. Liao, Andrew L. Cooper
Abstract Radial colour gradients within galaxies arise from gradients of stellar age, metallicity, and dust reddening. Large samples of colour gradients from wide-area imaging surveys can be used to constrain galaxy formation models. Here we measured colour gradients for low-redshift galaxies using photometry from the 9th DESI Legacy Imaging Survey (LS), which reaches r ∼ 24 over ∼14,000 deg2. We investigate empirical relationships between colour gradients, M*, and sSFR. We compared our results with the prediction of the Illustris TNG-100 simulation using SDSS mock images.
星系内的径向颜色梯度是由恒星年龄、金属丰度和尘埃变红的梯度引起的。来自广域成像调查的大量颜色梯度样本可以用来约束星系形成模型。在这里,我们使用第9次DESI遗产成像调查(LS)的光度测量法测量了低红移星系的颜色梯度,其值达到r ~ 24 ~ 14000°2。我们研究了颜色梯度、M*和sSFR之间的经验关系。我们将我们的结果与使用SDSS模拟图像的Illustris TNG-100模拟的预测结果进行了比较。
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引用次数: 1
Gap opening by planets in discs with magnetised winds 行星在带磁化风的圆盘中打开间隙
Pub Date : 2021-08-01 DOI: 10.1093/mnras/stac1774
V. Elbakyan, Yinhao Wu, S. Nayakshin, G. Rosotti
Abstract Planets open deep gaps in protoplanetary discs when their mass exceeds a gap opening mass, Mgap. We use one- and two-dimensional simulations to study planet gap opening in discs with angular momentum transport powered by MHD disc winds. We parameterise the efficiency of the MHD disc wind angular momentum transport through a dimensionless parameter αdw, which is an analogue to the turbulent viscosity αv. We find that magnetised winds are much less efficient in counteracting planet tidal torques than turbulence is. For discs with astrophysically realistic values of αdw, Mgap is always determined by the residual disc turbulence, and is a factor of a few to ten smaller than usually obtained for viscous discs. We introduce a gap opening criterion applicable for any values of αv and αdw that may be useful for planet formation population synthesis.
当行星的质量超过一个缺口打开质量Mgap时,原行星盘就会打开一个很深的缺口。我们利用一维和二维模拟研究了由MHD盘风驱动的角动量输运的行星盘隙打开。我们通过一个类似于湍流粘度αv的无量纲参数αdw来参数化MHD圆盘风角动量输运效率。我们发现磁化风在抵消行星潮汐扭矩方面比湍流效率低得多。对于具有天体物理真实值αdw的圆盘,Mgap总是由剩余的圆盘湍流决定,并且比通常得到的粘性圆盘小几到十倍。我们引入了一个适用于任意αv和αdw值的间隙打开判据,这可能对行星形成种群的合成有用。
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引用次数: 2
Anatomy of Galactic Star Formation: Roles of Different Modes of Gas Accretion, Feedback, and Recycling 银河恒星形成的解剖:不同模式的气体吸积、反馈和再循环的角色
Pub Date : 2021-08-01 DOI: 10.1017/S1743921322004823
M. Noguchi
Abstract Existence of the cold-mode gas accretion along with the hot-mode accretion can explain the diversity in the galactic star formation history across galaxy mass. We examine the role of various physical processes in producing the observed diversity.
冷模式气体吸积与热模式气体吸积的同时存在,可以解释星系恒星形成历史在星系质量上的多样性。我们研究了各种物理过程在产生观察到的多样性中的作用。
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引用次数: 0
Physics of the atmospheric escape driven by EUV photoionization heating: Classification of the hydrodynamic escape in close-in planets 由极紫外光离加热驱动的大气逸出的物理学:近地行星流体动力学逸出的分类
Pub Date : 2021-08-01 DOI: 10.1017/S1743921322003556
Hiroto Mitani, Riouhei Nakatani, N. Yoshida
Abstract The intense extreme ultraviolet radiation heats the upper atmosphere of close-in exoplanets and drives the atmospheric escape. The escaping process determines the planetary evolution of close-in planets. The mass loss rate depends on the UV flux at the planet. We introduce the relevant physical quantities which describe the dominant physics in the atmosphere. We find that the equilibrium temperature and the characteristic temperature determine whether the system becomes energy-limited or recombination-limited. We classify the observed close-in planets using the physical conditions. We also find that many of the Lyman-α absorptions detected planets receive intenser flux than the critical flux which can be determined from physical conditions. Our classification method can quantitatively reveal whether the EUV is not strong enough to drive the outflow or the Lyman- α absorption is not detected for some reason (e.g. stellar wind confinement). We also discuss the thermo-chemical structure of hydrodynamic simulations with the relevant physics.
强烈的极紫外辐射加热近地系外行星的上层大气,驱动大气逃逸。逃逸过程决定了近地行星的行星演化。质量损失率取决于行星上的紫外线通量。我们介绍了描述大气中主要物理性质的相关物理量。我们发现平衡温度和特征温度决定了系统是能量受限还是重组受限。我们用物理条件对观测到的近地行星进行分类。我们还发现,许多探测到莱曼α吸收的行星接收的通量比可由物理条件确定的临界通量更强。我们的分类方法可以定量地揭示EUV是否不足以驱动流出,或者由于某些原因(如恒星风限制)没有检测到莱曼α吸收。我们还讨论了水动力模拟的热化学结构与相关物理。
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引用次数: 0
Is star formation in gas-rich bars suppressed? 在富含气体的棒状结构中恒星的形成是否受到抑制?
Pub Date : 2021-08-01 DOI: 10.1017/S1743921322003775
F. Maeda
Abstract Whether the star formation efficiency (SFE) in the bar region is lower than those in the other regions in a barred galaxy has recently been debated. We statistically investigate the SFEs along the bars in nearby gas-rich massive star-forming barred galaxies by distinguishing the center, bar-end, and bar regions for the first time. The molecular gas surface density is derived from archival CO(1–0) and/or CO(2–1) data and the star formation rate surface density is derived from a linear combination of far-ultraviolet and mid-infrared intensities. To distinguish the three regions, we targeted 18 galaxies with a large apparent bar length (≥ 75"). The resulting SFE in the bars is about 0.6 – 0.8 times lower than that in the disks, which suggests the star formation in the bars tends to be systematically suppressed.
棒状星系中棒状区域的恒星形成效率(SFE)是否比其他区域低,一直是人们争论的焦点。我们首次通过区分中心、棒端和棒区,统计研究了附近富含气体的大质量恒星形成棒星系中沿棒的sfe。分子气体表面密度由CO(1-0)和/或CO(2-1)档案数据得出,恒星形成率表面密度由远紫外和中红外强度的线性组合得出。为了区分这三个区域,我们选择了18个视条长较大(≥75”)的星系作为目标。由此产生的星条形结构中的SFE比星条形结构中的SFE低约0.6 - 0.8倍,这表明星条形结构中的恒星形成倾向于被系统地抑制。
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引用次数: 0
期刊
Proceedings of the International Astronomical Union
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