We present the size, shape and flux densities at millimeter continuum wavelengths, based on ALMA science verification observations in Band 3 (~94.6 GHz) and Band 6 (~228.7 GHz), from the binary Mira A (o Ceti) and Mira B. The Mira AB system has been observed with ALMA at a spatial resolution of down to ~25 mas. The extended atmosphere of Mira A and the wind around Mira B sources are resolved and we derive the size of Mira A and of the ionized region around Mira B. The spectral indices within Band 3 (between 89-100 GHz) and between Band 3 and Band 6 are also derived. The spectral index of Mira A is found to change from 1.71+-0.05 within Band 3 to 1.54+-0.04 between Band 3 and 6. The spectral index of Mira B is 1.3+-0.2 in Band 3, in good agreement with measurements at longer wavelengths. However it rises to 1.72+-0.11 between the bands. For the first time the extended atmosphere of a star is resolved at these frequencies and for Mira A the diameter is ~3.8x3.2 AU in Band 3 (with brightness temperature Tb~5300 K) and ~4.0x3.6 AU in Band 6 (Tb~2500 K). Additionally, a bright hotspot of ~0.4 AU and with Tb~10000 K is found on the stellar disc of Mira A. The size of the ionized region around the accretion disk of Mira B is found to be ~2.4 AU. The emission around Mira B is consistent with that from a partially ionized wind of gravitationally bound material from Mira A close to the accretion disk of Mira B. The Mira A atmosphere does not fully match predictions, with brightness temperatures in Band 3 significantly higher than expected, potentially due to shock heating. The hotspot is likely due to magnetic activity and could be related to the previously observed X-ray flare of Mira A.
Resolving the outer ring of HD 38206 using ALMA and constraining limits on planets in the system
HD 38206是天鸽座星协中的一颗A0V恒星,拥有一个由IRAS首次发现的碎片盘。斯皮策和赫歇尔的进一步观测表明,这个圆盘有两个组成部分,可能类似于太阳系的小行星和柯伊伯带。这颗恒星的年轻年龄使其成为直接成像行星搜索的主要目标。系统中可能的行星可以使用碎片盘来限制。在这里,我们提出了第一ALMA观测系统的柯伊伯带,并适合他们使用的前向建模MCMC方法。我们探测到一个扩展的尘埃盘,峰值在180 au左右,宽度为140 au。椎间盘接近边缘,显示出不对称的初步迹象,最佳偏心率为$0.25^{+0.10}_{-0.09}$。我们使用拟合参数来确定冷带内部行星质量的限制。我们确定至少需要四颗行星,每颗行星的最小质量为0.64 M $_J$,以清除小行星和柯伊伯带之间的差距。如果我们假设最外层的行星负责圆盘的搅动,其内缘的位置和圆盘的偏心率,那么我们可以更紧密地预测其偏心率,质量和半长轴为$e_{\rm{p}}=0.34^{+0.20}_{-0.13}$,$m_{\rm{p}}=0.7^{+0.5}_{-0.3}\,\rm{M}_{\rm{J}}$和$a_{\rm{p}}=76^{+12}_{-13}\,\rm{au}$。
The ALMA-ATOMS-QUARKS survey: Resolving a chemically rich massive protostellar outflow
Yunnan University(云南大学);Shanghai Astronomical Observatory, Chinese Academy of Sciences(中国科学院上海天文台);Max Planck Institute for Astronomy(马克斯·普朗克天体物理研究所);Peking University(北京大学);Xinjiang Astronomical Observatory, Chinese Academy of Sciences(中国科学院新疆天文台);University of Chinese Academy of Sciences(中国科学院大学);National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台);S. N. Bose National Centre for Basic Sciences(S.N. Bose基础科学国立中心);University of Science and Technology, Korea (UST)(韩国科学技术院);Korea Astronomy and Space Science Institute(韩国天文学与空间科学研究所);University of Debrecen(德布勒森大学);Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS(中国科学院国家天文台拉美天文中心);University of Oslo(奥斯陆大学);The University of Tokyo(东京大学);Tsinghua University(清华大学);Kyushu University(九州大学)
A surprisingly large asymmetric ejection from Mira A
Chalmers University of Technology(查尔姆斯理工大学);Universidad Nacional Autónoma de Honduras(洪都拉斯国立自治大学);Georgia Institute of Technology(佐治亚理工学院);European Southern Observatory(欧洲南方天文台);University of Oslo(奥斯陆大学)
Resolving the terrestrial planet-forming region of HD 172555 with ALMA: I. Post-impact dust distribution
Trinity College Dublin, the University of Dublin(都柏林三一学院,都柏林大学);Malaghan Institute of Medical Research(马拉甘医学研究所);University of Exeter(埃克塞特大学);Space Science Institute(太空科学研究所);University of Arizona(亚利桑那大学);University of Cambridge(剑桥大学);Towson University(陶森大学)
The solar chromosphere at millimetre and ultraviolet wavelengths. I. Radiation temperatures and a detailed comparison
阿塔卡马大型毫米/亚毫米阵列(ALMA)的太阳观测为我们提供了太阳色球层亮温的直接测量。我们研究的温度分布与ALMA带6(在1.21,1.22,1.29,和1.3毫米的四个子带)在不同的地区,并在附近的,一个太阳黑子,包括准安静和活跃的地区与不同数量的底层磁场。我们将这些温度与在近紫外和远紫外(UV)波长(以及光学薄远紫外光谱的线芯强度)下获得的温度进行比较,这些温度与界面区域成像光谱仪(IRIS)探测器共同观测。这些包括Mg II k 279.6 nm和Mg II h 280.4 nm线的发射峰和核心,以及C II 133.4 nm、O I 135.6 nm和Si IV 139.4 nm的线核心,对中高色球层和低过渡区进行采样。分裂的ALMA子带导致在个别温度图的空间分辨率略有增加,因此,解决较小规模的结构相比,与标准的平均例程。我们发现,辐射温度有不同的,虽然有些重叠,在不同的波长和不同的磁区的分布。然而,ALMA温度与UV诊断温度的比较应非常谨慎地解释,前者是在局部热力学平衡(LTE)条件下形成的,后者是在非LTE条件下形成的。ALMA波段6的平均辐射温度与IRIS C II线提取的辐射温度在所有区域相似,除了太阳黑子和孔隙,其中C II具有较高的辐射温度。在所有的磁性区域,镁II线与最低的平均辐射温度在我们的样品。这些将为未来的数值模型提供约束。
Constraining properties of dust formed in Wolf-Rayet binary WR 112 using mid-infrared and millimeter observations
Yale University(耶鲁大学);California Institute of Technology(加州理工学院);University of Edinburgh(爱丁堡大学);University of Tokyo(东京大学);Netherlands Institute for Radio Astronomy(荷兰射电天文研究所);University of Amsterdam(阿姆斯特丹大学);Arkansas Tech University(阿肯色理工大学);The University of Sydney(悉尼大学);Caltech(加州理工学院);Max Planck Institute for Radio Astronomy(马克斯·普朗克射电天文研究所)