The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
J. Davy Kirkpatrick, Christopher R. Gelino, Jacqueline K. Faherty, Aaron M. Meisner, Dan Caselden, Adam C. Schneider, Federico Marocco, Alfred J. Cayago, R. L. … 展开作者
J. Davy Kirkpatrick, Christopher R. Gelino, Jacqueline K. Faherty, Aaron M. Meisner, Dan Caselden, Adam C. Schneider, Federico Marocco, Alfred J. Cayago, R. L. Smart, Peter R. Eisenhardt, Marc J. Kuchner, Edward L. Wright, Michael C. Cushing, Katelyn N. Allers, Daniella C. Bardalez Gagliuffi, Adam J. Burgasser, Jonathan Gagne, Sarah E. Logsdon, Emily C. Martin, James G. Ingalls, Patrick J. Lowrance, Ellianna S. Abrahams, Christian Aganze, Roman Gerasimov, Eileen C. Gonzales, Chih-Chun Hsu, Nikita Kamraj, Rocio Kiman, Jon Rees, Christopher Theissen, Kareem Ammar, Nikolaj Stevnbak Andersen, Paul Beaulieu, Guillaume Colin, Charles A. Elachi, Samuel J. Goodman, Leopold Gramaize, Leslie K. Hamlet, Justin Hong, Alexander Jonkeren, Mohammed Khalil, David W. Martin, William Pendrill, Benjamin Pumphrey, Austin Rothermich, Arttu Sainio, Andres Stenner, Christopher Tanner, Melina Thevenot, Nikita V. Voloshin, Jim Walla, Zbigniew Wedracki
备注：
101 pages, 31 figures, accepted for publication in the Astrophysical Journal Supplement Series
We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time. Using published photometry and spectroscopy as well as our own follow-up, we present an array of color-magnitude and color-color diagrams to further characterize census members, and we provide polynomial fits to the bulk trends. Using these characterizations, we assign each object a $T_{\rm eff}$ value and judge sample completeness over bins of $T_{\rm eff}$ and spectral type. Except for types $\ge$ T8 and $T_{\rm eff} <$ 600K, our census is statistically complete to the 20-pc limit. We compare our measured space densities to simulated density distributions and find that the best fit is a power law ($dN/dM \propto M^{-α}$) with $α= 0.6{\pm}0.1$. We find that the evolutionary models of Saumon & Marley correctly predict the observed magnitude of the space density spike seen at 1200K $< T_{\rm eff} <$ 1350K, believed to be caused by an increase in the cooling timescale across the L/T transition. Defining the low-mass terminus using this sample requires a more statistically robust and complete sample of dwarfs $\ge$Y0.5 and with $T_{\rm eff} <$ 400K. We conclude that such frigid objects must exist in substantial numbers, despite the fact that few have so far been identified, and we discuss possible reasons why they have largely eluded detection.
In order to obtain a complete census of the stellar and sub-stellar population, down to a few M$_{Jup}$ in the $\sim1$ Myr old Orion Nebula Cluster, we used the infrared channel of the Wide Field Camera 3 of the Hubble Space Telescope with the F139M and F130N filters. These bandpasses correspond to the $1.4 μ$m H$_2$O absorption feature and an adjacent line-free continuum region. Out of $4,504$ detected sources, $3,352$ (about $75\%$) appear fainter than m$_{130}=14$ (Vega mag) in the F130N filter, a brightness corresponding to the hydrogen-burning limit mass (M$\simeq 0.072 M_\odot$) at $\sim…
The Montreal Open Clusters and Associations (MOCA) Database: A Census of Nearby Associations, Open Clusters, and Young Substellar Objects within 500 pc of the Sun
Planétarium de Montréal, Espace pour la Vie（蒙特利尔天文馆，生命空间）；Trottier Institute for Research on Exoplanets, Université de Montréal（特罗蒂尔系外行星研究所，蒙特利尔大学）；Department of Astrophysics, American Museum of Natural History（天体物理系，美国自然历史博物馆）；Department of Astronomy, Columbia University（天文学系，哥伦比亚大学）；School of Physical Sciences, The Open University（物理科学学院，开放大学）
Spectroscopy of brown dwarf candidates in IC 348 and the determination of its substellar IMF down to planetary masses
上下文棕矮星代表了我们银河系中相当大的一部分恒星成分，并占据了恒星和行星质量制度之间的过渡。但是，对于这些组织的形成过程，没有达成一致意见。目标。我们对年轻的邻近星系团IC 348进行了一次大规模的调查，以揭示其低质量的褐矮星人口，并研究亚恒星区域的星系团性质。方法.使用加拿大-法国-夏威夷望远镜（CFHT）的MegaCam和WIRCam拍摄的深光学和近红外图像用于选择光度候选成员。对大部分候选人进行了光谱跟踪，以评估他们的年轻程度和成员资格。结果我们通过光谱确认了IC 348星系团的16个新成员，其中包括13颗褐矮星，这对该星系团的亚恒星普查做出了重大贡献，而以前只知道30颗褐矮星。新成员中有五个具有L0光谱类型，这是迄今为止在该集群中发现的最新类型的对象。在300万年前，演化模型估计这些褐矮星的质量约为木星的13倍。结合新成员和以前的星团普查，我们构建了IMF完整的13个木星质量。结论. IC 348的IMF很好地拟合了对数正态函数，与其他年轻星团相比，我们没有看到质量函数变化到行星质量的证据。
Discovery of a Highly Unequal-Mass Binary T Dwarf with Keck Laser Guide Star Adaptive Optics: A Coevality Test of Substellar Theoretical Models and Effective Temperatures
（节略）在野外棕矮星中，质量比高度不等的双星是很罕见的，已知的统计数据是q^（4.9+/-0.7）。然而，这样的系统可以测试的联合精度的演变和大气模型，在coevality的约束下（“等时线测试”）。我们使用目前已知的两个最极端的亚星双星，T1+T6 \eps Ind Bab双星和新发现的0.14”T2.0+T7.5双星，2 MASS 1209- 10 AB进行了这项测试。根据H-R图上各组分的位置，模型成功地表明这些系统是同时代的，内部年龄差分别为log（年龄）= 0.5{+0.4}{-0.3}和-0.8+/-1.3 dex。然而，从H-R图推导出的\eps Ind Bab的总质量（~80 Mjup）与报道的动力学质量不一致。这个问题，这是独立的假设年龄的系统，可以解释为一个~50-100 K的系统误差，在模型大气拟合;使两个质量测定一致导致推断年龄~6 Gyr的\eps Ind系统，比以前假设的。总的来说，这里研究的两个T矮星双星，以及最近在年龄和质量基准系统中T矮星的结果，在演化模型和/或模型大气中产生小（~100 K）误差的证据，但不是显着更大。最后，2 MASS 1209-10AB的二进制性质降低了其作为主要T3近红外光谱分型标准的实用性;我们建议SDSS 1206+28作为替代品。
We present the design and implementation of a medium-band near-IR filter tailored for detecting low-mass stars and brown dwarfs from the summit of Maunakea. The W-band filter is centered at 1.45 micron with a bandpass width of 6%, designed to measure the depth of the H2O water absorption prominent in objects with spectral types of M6 and later. When combined with standard J- and H-band photometry, the W-band filter is designed to determine spectral types to $\approx$1.4 subtypes for late-M and L dwarfs, largely independent of surface gravity and reddening. This filter's primary application is …
我们已经进行了近红外（NIR）自行调查，Sondage Infrarouge de Mouvement Propre，以发现太阳附近的超冷矮星（UCD）。该调查是通过在南半球的Cerro Tololo美洲天文台1.5 m望远镜和北半球的Mont-Mégantic天文台1.6 m望远镜上使用Caméra PAanoramique Proche-infraRouge对天空的$\sim28\%$进行成像来进行的，并将这些观测的源位置与两微米全天调查点源目录（2 MASS PSC）进行比较。使用额外的颜色标准来进一步区分不需要的天体物理源。我们提出了一个近红外光谱的后续行动的169 M，L和T矮星的结果。其中发现了2颗年轻的野棕矮星，6颗异常红色的M和L型矮星，25颗异常蓝色的M和L型矮星，2颗候选的未解决的L+T双星，以及24颗奇特的UCD。此外，我们还在已知的天体上增加了9个L/T转换矮星（L 6-T4.5）。
Substellar Objects in Nearby Young Clusters (SONYC) II: The Brown Dwarf Population of Rho Ophiuchi
SONYC（Substellar Objects in Nearby Young Clusters）是一个调查计划，旨在调查附近恒星形成区域中质量低于氘燃烧极限的褐矮星的频率和性质。在这第二篇论文中，我们提出的结果~ 100万年前的星团蛇夫座ρ，结合我们自己的深光学和近红外成像使用斯巴鲁测光从2微米全天巡天和斯皮策太空望远镜。在从iJK测光中选择的候选者中，我们已经通过低分辨率红外光谱确认了三个-包括一个质量接近氘极限的新棕矮星-作为可能的集群成员。我们还确定了27个亚恒星候选人与中红外过量一致的磁盘发射，其中16个是新的，11个是以前光谱确认的棕矮星。高消光率和多变的消光率使得在该区域获得完整的亚恒星星族很困难。然而，目前的数据表明，它的低质量恒星与褐矮星的比例与其他几个星团的报告相似，尽管高于Scholz等人2009年发现的NGC 1333。
We present preliminary trigonometric parallaxes of 184 late-T and Y dwarfs using observations from Spitzer (143), USNO (18), NTT (14), and UKIRT (9). To complete the 20-pc census of $\ge$T6 dwarfs, we combine these measurements with previously published trigonometric parallaxes for an additional 44 objects and spectrophotometric distance estimates for another 7. For these 235 objects, we estimate temperatures, sift into five 150K-wide $T_{\rm eff}$ bins covering the range 300-1050K, determine the completeness limit for each, and compute space densities. To anchor the high-mass end of the brown…
White dwarfs in the UKIDSS Large Area Survey: The Substellar Companion Fraction
我们提出了一个近红外测光搜索未解决的亚恒星同伴和碎片盘周围的白矮星在UKIRT红外深空大面积调查。我们交叉相关SDSS DR 4和McCook & Sion目录的白矮星与UKIDSS DR 8生产3109和163个独特的匹配分别。冷却模型适用于DA白矮星子样本的光学测光，并推广到近红外。然后与观测到的测光进行比较，以确定那些具有与冷伴星或碎片盘的存在相一致的近红外过量的恒星。在存在的地方，我们已经估计了任何假定的伴星的近似光谱类型，或者碎片盘温度的上限。我们总共确认了14-16个新的候选白矮星+极低质量恒星系统，9-11个候选白矮星+棕矮星系统，3个候选白矮星+碎片盘。我们对所有DA白矮星的未解决（<2英寸）伴星设定了下限，从而评估UKIDSS对此类物体的敏感性。我们使用该结果来估计f（WD+dL）>0.4+/-0.3%，f（WD+dT）>0.2%和f（WD+BD）>0.5+/-0.3%的未分辨二元分数。
We report the discovery of substellar objects in the young star cluster IC 348 and the neighboring Barnard 5 dark cloud, both at the eastern end of the Perseus star-forming complex. The substellar candidates are selected using narrowband imaging, i.e., on and off photometric technique with a filter centered around the water absorption feature at 1.45 microns, a technique proven to be efficient in detecting water-bearing substellar objects. Our spectroscopic observations confirm three brown dwarfs in IC 348. In addition, the source WBIS 03492858+3258064, reported in this work, is the first conf…
Toward a Spectroscopic Census of White Dwarfs Within 40 parsecs of the Sun
我们目前的初步调查结果，旨在显着增加光谱确认的白矮星的本地普查的范围和完整性。目前对附近白矮星的普查只完成了大约20秒差距的太阳，一个包括大约130个白矮星的体积，样本太小，无法进行详细的统计分析。这次普查主要是基于对具有非常大自行的恒星的后续调查。我们在这里描述的基础上的一种方法，将导致一个目录的白矮星在40秒差距的太阳和天球赤道以北，从而增加了8倍的北部天空普查的范围。白矮星候选人确定从SUPERBLINK自行数据库，使我们能够调查恒星自行限制mu>40 mas yr-1，同时尽量减少附近物体的运动学偏差。选择标准和距离估计是基于颜色幅度和减少自行图的组合。我们的后续光谱观测活动迄今已发现了193颗新的白矮星，其中我们确认了127颗DA星（包括9颗DA+dM星和4颗磁性星）、1颗DB星、56颗DC星、3颗DQ星和6颗DZ星。我们进行光谱分析的子样本的84个DA，并提供其大气参数。特别是，我们确定了11个新的白矮星的光谱距离在25 pc的太阳，包括5个候选人的D<20 pc的子集。
We present Spitzer 3.6$μ$m and 4.5$μ$m follow-up of 170 candidate extremely cool brown dwarfs newly discovered via the combination of WISE and NEOWISE imaging at 3$-$5$μ$m. CatWISE, a joint analysis of archival WISE and NEOWISE data, has improved upon the motion measurements of AllWISE by leveraging a $>$10$\times$ time baseline enhancement, from 0.5 years (AllWISE) to 6.5 years (CatWISE). As a result, CatWISE motion selection has yielded a large sample of previously unrecognized brown dwarf candidates, many of which have archival detections exclusively in the WISE 4.6$μ$m (W2) channel, sugges…
Deep H$α$ Imaging Survey of IC 348 with the Hubble Space Telescope: I. Accretion Properties of Stellar and Substellar Objects
University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；University of Virginia（弗吉尼亚大学）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）；Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森尼天体物理中心）；California Institute of Technology（加州理工学院）；Australian National University（澳大利亚国立大学）；University of Nevada, Las Vegas（内华达大学拉斯维加斯分校）
我们提出了一个普查的12,060光谱的蓝色物体（$(g-r)_0<-0.25$）在斯隆数字巡天（SDSS）数据发布8（DR 8）。作为数据发布的一部分，所有光谱都与恒星、星系和类星体的48个模板光谱进行了交叉相关，以确定最佳匹配。我们通过眼睛将蓝色光谱与SDSS DR 8中指定的模板进行了比较。其中10，856个物体与其指定的模板匹配，170个由于信噪比（S/N）低而无法分类，1034个被赋予新的分类。我们确认了7458颗DA白矮星，1145颗DB白矮星，273颗较为罕见的白矮星（包括碳、DZ、DQ和磁），294颗亚矮星O星，648颗亚矮星B星，679颗蓝色水平分支星，1026颗蓝色离散星，13颗激变变星，129颗白矮星- M矮星双星，36颗光谱与DO白矮星相似的天体，179个类星体和10个星系。我们提供了这些天体的两个表格，与模板匹配的样本光谱，显示按眼睛分组的所有光谱的图，以及显示每个分类的位置，颜色，视星等，自行等的诊断图。未来的调查将能够使用类似于我们识别的每个类别中的恒星的模板来自动分类蓝色恒星，包括罕见类型。
Very Low-Mass Stellar and Substellar Companions to Solar-like Stars From MARVELS VI: A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646
Distinguishing classes within substellar objects and understanding their formation and evolution need larger samples of substellar companions such as exoplanets, brown dwarfs, and low-mass stars. In this paper, we look for substellar companions using radial velocity surveys of FGK stars with the SOPHIE spectrograph at the Observatoire de Haute-Provence. We assign here the radial velocity variations of 27 stars to their orbital motion induced by low-mass companions. We also constrained their plane-of-the-sky motion using HIPPARCOS and Gaia Data Release 1 measurements, which constrain the true m…
Very Low-mass Stellar and Substellar Companions to Solar-like Stars from Marvels III: A Short-Period Brown Dwarf Candidate Around An Active G0Iv Subgiant
Predicting the detection yields of giant planets and brown dwarfs with CSST astrometry
Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交大李政道研究所）；School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；School of Astronomy and Space Sciences, University of Chinese Academy of Sciences (UCAS)（中国科学院大学天文学与空间科学学院）；School of Physics and optoelectronic engineering, Anhui University（安徽大学物理与光电工程学院）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
