本文报道了利用英澳望远镜上的超高分辨率设备对随时间变化的星际吸收向κ Vel方向的超高光谱分辨率观测。得到了星际Ca I、Ca II、K I、Na I和CH的探测值,同时报道了C_2的柱密度上限。结果显示,自4年前观测以来,K I和Ca I的柱密度持续增加,因为恒星的横向运动使其垂直于视线约10 AU。谱线轮廓模型拟合的光谱和两个主要的窄组分(A和B)被确定为所有物种除了CH。柱密度N(KI)被发现增加了82 + 10 - 9%之间1994年和2006年,而N(Ca I)被发现增加了32 +-5%,在较短的时间内2002-2006年。谱线宽度用于限制动力学温度T_k,A < 671 + 18 - 17 K和T_k,B < 114 + 15 - 14 K。电子密度由Ca I / Ca II比值决定,而Ca I / Ca II比值又将总数密度的下限设为n_A > 7 * 10^3 cm^-3和n_B > 2 * 10^4 cm^-3。根据Ca I / K I比值估计钙消耗。与贝尔等人(2005)的化学模型进行比较,证实了高的数密度,最佳拟合模型的数密度为n = 5 * 10^4 cm^-3。对这颗恒星的弥漫星际带(DIB)的第一次测量是在两个时期进行的,但在大约9年的时间里,它们的变化只有<40%的上限。DIBs对于测量的E(B-V)来说异常微弱,似乎表现出与猎户座相似的行为。λ5780与λ5797 DIB的等效宽度之比是已知的最高之一,这可能表明λ5797的载体对紫外辐射比对局部密度更敏感。
英文摘要:
Ultra-high spectral resolution observations of time-varying interstellar absorption towards κ Vel are reported, using the Ultra-High Resolution Facility on the Anglo-Australian Telescope. Detections of interstellar Ca I, Ca II, K I, Na I and CH are obtained, whilst an upper limit on the column density is reported for C_2. The results show continued increases in column densities of K I and Ca I since observations ~ 4 yr earlier, as the transverse motion of the star carried it ~ 10 AU perpendicular to the line of sight. Line profile models are fitted to the spectra and two main narrow components (A & B) are identified for all species except CH. The column density N(K I) is found to have increased by 82 +10-9 % between 1994 and 2006, whilst N(Ca I) is found to have increased by 32 +- 5 % over the shorter period of 2002-2006. The line widths are used to constrain the kinetic temperature to T_k,A < 671 +18-17 K and T_k,B < 114 +15-14 K. Electron densities are determined from the Ca I / Ca II ratio, which in turn place lower limits on the total number density of n_A > 7 * 10^3 cm^-3 and n_B > 2 * 10^4 cm^-3. Calcium depletions are estimated from the Ca I / K I ratio. Comparison with the chemical models of Bell et al. (2005) confirms the high number density, with n = 5 * 10^4 cm^-3 for the best-fitting model. The first measurements of diffuse interstellar bands (DIBs) towards this star are made at two epochs, but only an upper limit of < 40 % is placed on their variation over ~ 9 years. The DIBs are unusually weak for the measured E(B-V) and appear to exhibit similar behaviour to that seen in Orion. The ratio of equivalent widths of the λ5780 to λ5797 DIBs is amongst the highest known, which may indicate that the carrier of λ5797 is more sensitive to UV radiation than to local density.
School of Mathematics and Physics, Anhui Jianzhu University(安徽建筑大学数学与物理学院);Department of Physics and Astronomy, University of Missouri(密苏里大学物理与天文学系);Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences(中国科学院高能物理研究所粒子天体物理重点实验室)
Anomalous Diffuse Interstellar Bands in the Spectrum of Herschel 36. I. Observations of Rotationally Excited CH and CH+ Absorption and Strong, Extended Redward Wings on Several DIBs
Interstellar Aromatic Infrared Bands: IR absorption spectroscopy of the lowest triplet state of naphthalene
HFML-FELIX(高磁场与极低温设施-自由电子激光实验室);Van 't Hoff Institute for Molecular Sciences, University of Amsterdam(范特霍夫分子科学研究所,阿姆斯特丹大学);Anton Pannekoek Institute for Astronomy, University of Amsterdam(安东·潘内科克天文学研究所,阿姆斯特丹大学)
Inverse Raman scattering and the diffuse interstellar bands: an exploration of the systemic interconnections between spontaneous and inverse Raman scattering and extended red emission, Red Rectangle bands, and diffuse interstellar bands
Small-Scale HI Channel Map Structure is Cold: Evidence from Na I Absorption at High Galactic Latitudes
中性氢辐射的空间分布是研究星际介质物理的重要手段。在H I通道图中的小尺度结构通常被假定为探测速度场而不是真实的密度结构。在这项工作中,我们使用高分辨率的GALFA-H I观测和SDSS的50,985个类星体光谱直接测试了这一假设。我们测量了星际Na I D $_1$和Na I D $_2$吸收的等效宽度,并有力地得出结论:它们对H I中小尺度结构的柱密度的依赖性比对大尺度H I结构或总H I柱的依赖性更强。这与小尺度通道图结构由速度拥挤驱动的假设不一致。相反,这些数据支持这样的解释,即这种发射结构主要起源于寒冷、致密的星际物质,与寒冷的中性介质一致。
Investigation of Calcium Dust in the Interstellar Medium
Institute of Astronomy and Astrophysics, Academia Sinica(中央研究院天文及天文物理研究所);Department of Physics, National Tsing Hua University(国立清华大学物理系);SRON Space Research Organisation Netherlands(荷兰空间研究组织);Anton Pannekoek Institute for Astronomy, Universiteit van Amsterdam(阿姆斯特丹大学安东·潘内科克天文学研究所);National Synchrotron Radiation Research Center(国家同步辐射研究中心)
High resolution X-ray spectroscopy of the multiphase interstellar medium toward Cyg X-2
High resolution X-ray absorption spectroscopy is a powerful diagnostic tool for probing chemical and physical properties of the interstellar medium (ISM) at various phases. We present detections of K transition absorption lines from the low ionization ions of OI, OII, NeI, NeII, and NeIII, and the high ionization ones of OVI, OVII, OVIII, NeIX, and MgXI, as well as details of neutral absorption edges from Mg, Ne, and O in an unprecedented high quality spectrum of the low mass X-ray binary Cyg X-2. These absorption features trace the intervening interstellar medium which is indicated by the uns…
Aliphatic hydrocarbon content of the interstellar dust
在星际介质中,碳分布在气相和固相之间。然而,虽然大约一半的预期碳丰度可以在气相中解释,但星际尘埃中的含量存在相当大的不确定性。碳质粉尘的脂肪族组分特别令人感兴趣,因为当相对于背景辐射源观察时,它产生显著的3.4 $μ$ m吸收特征。3.4 $μ$ m吸收特征的光学深度与沿着视线的脂肪族碳C-H键的数目有关。如果已知星际尘埃中脂肪烃的吸收系数,则可以通过对3.4 $μ$ m星际吸收特征的定量分析来估计锁定在星际尘埃脂肪烃组分中的碳的柱密度。我们通过实验模拟星际/拱星条件产生了星际尘埃的实验室模拟物。这些尘埃类似物的光谱与天文观测结果非常吻合。结合FTIR和$^{13}$ C NMR谱测量了类似物中脂肪烃的吸收系数。发现两种星际类似物的吸收系数非常接近(4.76(8)$\times$ 10 $^{-18}$ cm group $^{-1}$和4.69(14)$\times$ 10 $^{-18}$ cm group $^{-1}$),不到使用小脂肪族分子研究中获得的吸收系数的一半。由此获得的结果允许直接校准天文观测,提供了对星际介质中脂肪碳数量的严格估计。
Comparing absorption from classic tracers of the diffuse interstellar medium at optical and radio wavelengths along the same sightlines
目的比较从漫射星际介质沿同一视线的射电和光学吸收线剖面获得的信息。方法我们比较了新的和现有的21 cm HI和3.4 mm HCO+剖面与光学示踪剂Ca II,NaI,和KI来自Tappe(2004)未发表的论文。结果与太阳丰度相比,光学追踪的原子都是严重亏损的,只有HI和HCO+的积分光学深度与E(B-V)有很好的相关性。HCO+是迄今为止运动学分布最有限的物种,其最西的线依次为KI、HI、NaI和CaII。CaII在柱密度和运动学上都有单独的行为,因为它对更宽范围的温暖气体进行采样。冷中性介质NaI,KI,HI和HCO+的示踪剂在统计上共享相同的运动学空间,而在丰度上几乎没有相同程度的相关性。N(NaI)和N(KI)是相关的,是HI和HCO+的综合光学深度,但光学和无线电示踪剂之间的丰度相关性没有看到。在唯一的方向与测量的CH+的配置文件,2公里/秒的速度之间的CH+和CH,通常被解释为冲击气体的迹象,模仿HI相对于HCO+的移位。CH和HCO+出现在两条视线上的比例N(CH)/N(HCO+)=14.6和21.1,光学测量的N(CH),与之前在无线电和亚毫米波长确定的平均值12相比。
Extracting interstellar diffuse absorption bands from cool star spectra: Application to bulge clump giants in Baade's window
星际漫射带通常是从热星光谱中提取的,因为它们具有光滑连续谱的特征。它对可用目标的数量进行了严格的限制,并减少了对IS问题的潜在研究和对云映射的选择的使用。我们发展了一种新的自动拟合方法,适用于具有恒星大气参数的冷星光谱中的星际吸收。我们将此方法应用于红团簇星核球的高分辨率VLT FLAMES/GIRAFFE光谱中三个DIB的提取。结合所有恒星合成光谱、HITRAN-LBLRTM大气透射光谱和漫射带经验吸收剖面,确定了219颗目标星的6196、6204和6284 A DIB强度,并讨论了不确定性的来源。为了测试的DIB提取的灵敏度,我们相互比较的三个结果,并比较的DIB等效宽度与来自一个独立的消光图的基础上OGLE光度数据的变红。恒星、大气和星际混合模型可以很好地再现大多数恒星的光谱。对于宽而强的6284 A DIB,EW的测量不确定度较小,约为10- 15%。正如预期的那样,两个狭窄和较弱的DIB上的Underwear较大,并且发现从一个目标到另一个目标的变化很大。它们强烈地依赖于恒星的径向速度。三个频带之间的DIB-DIB相关性表明提取了有意义的信号。对于6284和6204 A DIB,等效宽度(EW)的恒星间变化也反映了OGLE消光图的特征。
Narrow absorption lines from intervening material in supernovae: III. Supernovae and their environments
Institut d’Estudis Espacials de Catalunya (IEEC)(加泰罗尼亚空间研究所);Institute of Space Sciences (ICE, CSIC)(空间科学研究所);European Southern Observatory(欧洲南方天文台);Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências, Universidade de Lisboa(里斯本大学科学学院天体物理与空间科学研究所)