我们从Herbig Ae磁性恒星HD 190073（V1295 Aql）的吸收光谱中确定了丰度。观测结果主要来自于在单个时期获得的HARPS光谱。我们接受这样的论点，即大量发射谱线的存在并不会破坏经典的丰度分析，尽管它可能会降低可实现的准确性。大多数元素的丰度与太阳系元素相近，但有几种元素的丰度偏离了2到3倍，这也是早期研究的结果。我们目前的定量测量超过60个发射线，峰值强度，等效宽度，和FWHM的。后者的范围从超过200 km/s（H-α，He D3）下降到10- 20 km/s（禁止线）。金属发射线具有中等宽度。我们避免建模，满足于一个成功的模型必须解释的观察结果的呈现。低激发的功能，如Na I D-线和[O I]出现与He I D 3，建议附近地区有广泛不同的Te和Ne发现在太阳色球层。[O I]和[Ca II]线显示尖锐的紫移特征。此外，[Fe II]线似乎弱存在于发射中。
英文摘要：
We determine abundances from the absorption spectrum of the magnetic Herbig Ae star HD 190073 (V1295 Aql). The observations are primarily from HARPS spectra obtained at a single epoch. We accept arguments that the presence of numerous emission lines does not vitiate a classical abundance analysis, though it likely reduces the achievable accuracy. Most abundances are closely solar, but several elements show departures of a factor of two to three, as an earlier study has also shown. We present quantitative measurements of more than 60 emission lines, peak intensities, equivalent widths, and FWHM's. The latter range from over 200 km/s (H-alpha, He D3) down to 10--20 km/s (forbidden lines). Metallic emission lines have intermediate widths. We eschew modeling, and content ourselves with a presentation of the observations a successful model must explain. Low-excitation features such as the Na I D-lines and [O I] appear with He I D3, suggesting proximate regions with widely differing Te and Ne as found in the solar chromosphere. The [O I] and [Ca II] lines show sharp, violet-shifted features. Additionally, [Fe II] lines appear to be weakly present in emission.
Diagnosing Mass Flows Around Herbig Ae/Be Stars Using the He I 10830 Line
我们检查他我10830配置文件的56赫比格Ae/Be星（HAEBES）的样本形态。我们发现显着差异HAEBES和CTTS的蓝移吸收（即质量外流）和红移吸收功能（即质量下降或吸积）的统计。我们的研究结果表明，在一般情况下，赫比格Be（HBe）的恒星不吸积材料从他们的内部磁盘以同样的方式作为CTTS，这被认为是通过磁层吸积吸积材料，而赫比格Ae（HAe）的恒星一般表现出磁层吸积的证据。我们发现没有证据表明，在我们的样本窄蓝移的吸收功能，这是典型的指标内盘风和常见的He I 10830配置文件的CTTS。缺乏内部磁盘风签名HAEBES，结合检测到的磁场对这些对象的缺乏，表明通过大磁层截断磁盘几个恒星半径以上的表面是不常见的HAe和晚型HBe恒星，因为它是CTTS。相反，在我们的HAEBE样品中发现了最大红移吸收速度中较小磁层的证据。平均而言，这些速度比CTTS的系统逃逸速度小，这表明吸积发生在更靠近恒星的地方。较小的磁层，和边界层吸积在HBe星的证据，可以解释不太常见的发生红移吸收HAEBES。有证据表明，较小的磁层可能是效率较低的驱动外流相比，CTTS磁层。
Optical Mass Flow Diagnostics in Herbig Ae/Be Stars
我们研究了广泛的质量流诊断在一个大样本的赫比格Ae/Be星（HAEBES）使用高分辨率的光谱。H-β和He I 5876埃谱线分别显示P-Cygni（30%）和逆P-Cygni（14%）形态的最高发生率。Fe II 4924埃的谱线也显示出大的P-Cygni分布（11%）。我们发现支持的许多结论，在一项研究的基础上分析的He I 10830埃线在一个大样本的HAEBES。也就是说，HAEBES表现出更小的部分蓝移吸收（即质量流出）和红移吸收（即质量下降或吸积）比它们的低质量表亲，经典的金牛T星（CTTS）。特别是，光学数据支持的结论，HAEBES显示红移吸收，一般来说，显示最大的红移吸收速度，其恒星的逃逸速度的小部分比CTTS。这表明HAEBE吸积流起源于其恒星的引力势比CTTS系统更深。此外，我们发现在蓝移吸收天体中缺乏内部盘风的签名，只有恒星风的签名被清楚地观察到。这些发现，以及缺乏检测到的磁场周围HAEBES，支持的想法，大磁层并不普遍周围HAEBES和吸积流，而不是介导的显着较小的磁层相对较小的截断半径（例如1-2恒星半径）。红移吸收在赫比格Ae星周围比在Be星周围更常见，这表明赫比格Be星可能通过边界层而不是沿着磁场线吸积。
Linking Signatures of Accretion with Magnetic Field Measurements - Line Profiles are not Significantly Different in Magnetic and Non-Magnetic Herbig Ae/Be Stars
Herbig Ae/Be星是年轻的前主序星，它们采样了低质量和高质量恒星之间结构和演化的过渡，为高质量恒星的吸积过程提供了关键的测试。很少有赫比格Ae/Be恒星探测到磁场，这就引发了一个问题，即为低质量恒星开发的磁层吸积范例是否可以扩展到更高的质量。我们提出了He I 10830的线轮廓64 Herbig Ae/Be星的磁场测量，以测试磁层吸积的物理制度，其功效仍然不确定。在5颗有磁场探测的恒星中，1颗表现出红移吸收，这表明恒星在下沉，2颗表现出蓝移吸收，这表明恒星在外流。在非磁性赫比格Ae/Be恒星中，红移和蓝移吸收曲线的比例非常相似，这表明恒星磁场不会影响He I 10830追踪的气体运动学。线轮廓形态与光度、自转速率、质量吸积速率或盘倾角无关。只有检测到磁场和一个几乎面对磁盘倾斜显示相关性（虽然对少数来源）。这为更弱的偶极子和更复杂的场拓扑结构提供了进一步的证据，因为恒星发展了辐射包络。磁性赫比格Ae/Be星的数量很少，这已经引起了人们对磁层吸积是否可以缩放到更高质量的问题;磁性赫比格Ae/Be星的吸积特征没有实质性的不同，这进一步怀疑它们以与经典金牛T星相同的方式吸积。
Measurements of gas mass in protoplanetary gas disks form the basis for estimating the conditions of planet formation. Among the most important constraints derived from disk diagnostics are the abundances of gas-phase species critical for understanding disk chemistry. Towards this end, we present direct line-of-sight measurements of H$_{2}$ and CO, employing UV absorption spectroscopy from $HST$-COS to characterize disk composition, molecular excitation temperatures, and spatial distribution in the circumstellar material around the Herbig Ae stars HK Ori and T Ori. We observe strong CO (N(CO) …
We identify 20 F-type Herbig stars and provide a list of 22 pre-main-sequence candidates from LAMOST DR8. The effective temperature, distance, extinction, stellar luminosity, mass, and radius are derived for each Herbig star based on optical spectra, photometry, Gaia EDR3 parallaxes, and pre-main-sequence evolutionary tracks. According to spectral energy distributions, 19 F-type Herbig stars belong to Class II YSOs, and one belongs to the flat-spectrum class. Four have Spitzer IRS spectra, of which three show extremely weak polycyclic aromatic hydrocarbons emissions, and three with both amorph…
HD 163296 is a Herbig Ae star that underwent a dramatic $\sim$0.8 magnitude drop in brightness in the V photometric band in 2001 and a brightening in the near-IR in 2002. Because the star possesses Herbig-Haro objects travelling in outflowing bipolar jets, it was suggested that the drop in brightness was due to a clump of dust entrained in a disk wind, blocking the line-on-sight toward the star. In order to quantify this hypothesis, we investigated the brightness drop at visible wavelengths and the brightening at near-IR wavelengths of HD 163296 using the Monte Carlo Radiative Transfer Code, H…
We derive a catalog of early-type emission-line stars including 30,048 spectra of 25,886 stars from LAMOST DR7, in which 3,922 have Simbad records. The sample is obtained using K-Nearest Neighbor and Random Forest methods and visually inspected. The spectra are classified into 3 morphological types (10 subtypes) based on H$α$ emission line profiles. Some spectra contaminated by nebula emission lines such as from HII regions are flagged in the catalog. We also provide a specific sub-catalog of 101 stars with the stellar wind by calculating stellar wind or accretion flow velocities based on P Cy…
Evolution of the dust/gas environment around Herbig Ae/Be stars
用KOSMA 3米望远镜观测了54颗Herbig Ae/Be星的CO和$^{13}$ CO发射线。通过拟合恒星的星周环境，研究了恒星及其星周环境的性质。该样品的$^{13}$ CO（2-1）谱线的平均线宽为1.87 km s $^{-1}$。对于小于$10^{6}$年的恒星，H $_{2}$的平均柱密度为$4.9\times10^{21}$ cm $^{-2}$，而对于大于$10^{6}$年的恒星，H $_{2}$的平均柱密度下降到$2.5\times10^{21}$ cm $^{-2}$。Herbig Ae星和Herbig Be星在相同年龄时的SEDs没有显著差异。红外过量随着年龄的增长而减少。在$10^{5}$年以后，包层质量和包层吸积率随年龄的增加而减小.样品的平均圆盘质量为$3.3\times10^{-2} M_{\sun}$。盘吸积速率比包层吸积速率下降得慢。CO谱线强度与包线质量之间有很强的相关性。
Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive, Ae/Be stars. Frequently, the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet driving-source are useful to map the large-scale jet emission and to explore the mass ejection history. The aim of this work was to search for large-scale optical Herbig-Haro (HH) objects lying in a wide field around a sample of IRAS sources, candidates to trace you…
Herbig stars can be classified into group I and group II depending on the shape of the far-IR excess from the spectral energy distribution. This separation may be evolutionary and related to the vertical structure of these disks. We aim to determine the emission height of Herbig disks and compare the resulting vertical extent of both groups. ALMA Band 6 observations of 12CO emission lines at sufficient velocity and spatial resolution of eight Herbig disks (four group I and four group II sources) are used to determine the emission heights from the channel maps via geometrical methods developed …
We analyze the physical conditions, chemical composition and other properties of the photoionized Herbig-Haro object HH~204 through Very Large Telescope (VLT) echelle spectroscopy and Hubble Space Telescope (\textit{HST}) imaging. We kinematically isolate the high-velocity emission of HH~204 from the emission of the background nebula and study the sub-arcsecond distribution of physical conditions and ionic abundances across the HH object. We find that low and intermediate-ionization emission arises exclusively from gas at photoionization equilibrium temperatures, whereas the weak high-ionizati…
A $λ=1.3$ millimeter Survey for Disks around Herbig Be Stars
Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森天体物理中心）；European Southern Observatory（欧洲南方天文台）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；School of Physics, Trinity College Dublin, the University of Dublin（都柏林大学三一学院物理学院）
The 2008-2009 outburst of the young binary system Z CMa unraveled by interferometry with high spectral resolution
Z CMa是一个年轻的双星系统，由一个Herbig主星和一个FU Ori伴星组成。这两个组成部分似乎都被活跃的吸积盘所包围，赫比格B 0还伴随着一个喷流。2008年11月，K.格兰金发现Z CMa爆发的幅度比过去25年中记录的任何光度变化都要大。为了研究爆发发生的最内部区域并了解其起源，我们于2009年12月在中等和高光谱分辨率模式下用ABER/VLTI观测了跨越Brγ发射线的两个二元分量。我们的观测结果表明，赫比格Be，负责增加的亮度，也产生了强大的Brγ发射，他们允许我们从不同的来源，通过定位在每个速度通过线的发射解开。考虑一个模型的开普勒磁盘单独未能再现不对称的光谱天体测量，这表明一个流出的主要贡献。
