White dwarf pollution by hydrated planetary remnants: Hydrogen and Metals in WD J204713.76-125908.9
Matthew J. Hoskin, Odette Toloza, Boris T. Gänsicke, Roberto Raddi, Detlev Koester, Anna Pala, Christopher J. Manser, Jay Farihi, Maria Teresa Belmonte, Mark Ho… 展开作者
Matthew J. Hoskin, Odette Toloza, Boris T. Gänsicke, Roberto Raddi, Detlev Koester, Anna Pala, Christopher J. Manser, Jay Farihi, Maria Teresa Belmonte, Mark Hollands, Nicola Gentile Fusillo, Andrew Swan
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14 pages, 5 figures Accepted for publication in Monthly Notices of the Royal Astronomical Society
WD J204713.76-125908.9 is a new addition to the small class of white dwarfs with helium-dominated photospheres that exhibit strong Balmer absorption lines and atmospheric metal pollution. The exceptional abundances of hydrogen observed in these stars may be the result of accretion of water-rich rocky bodies. We obtained far-ultraviolet and optical spectroscopy of WD J204713.76-125908.9 using the Cosmic Origin Spectrograph on-board the Hubble Space Telescope and X-shooter on the Very Large Telescope, and identify photospheric absorption lines of nine metals: C, O, Mg, Si, P, S, Ca, Fe and Ni. The abundance ratios are consistent with the steady state accretion of exo-planetesimal debris rich in the volatile elements carbon and oxygen, and the transitional element sulphur, by factors of seventeen, two, and four respectively compared to bulk Earth. The parent body has a composition akin to Solar System carbonaceous chondrites, and the inferred minimum mass, $1.6 \times 10^{20}$ g, is comparable to an asteroid 23 km in radius. We model the composition of the disrupted parent body, finding from our simulations a median water mass fraction of eight per cent.
A widely-held assumption is that each single white dwarf containing observable rocky debris requires the presence of at least one terrestrial or giant planet to have gravitationally perturbed the progenitor of the debris into the star. However, these planets could have been previously been engulfed by the star or escaped the system, leaving behind asteroids, boulders, cobbles, pebbles, sand and dust. These remaining small bodies could then persist throughout the host star's evolution into a white dwarf at ~2-100 au scales, and then be radiatively dragged into the white dwarf without the help o…
Tracing outer planetary systems through white dwarf pollution in wide binaries
Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Universidad de Valparaíso（瓦尔帕莱索大学）；NOIRLab（美国国家光学红外天文研究实验室）；University of Cambridge（剑桥大学）；Université de Montréal（蒙特利尔大学）
The Effects of Magnetic Accretion on the Spatial Extent of White Dwarf Pollution
JILA and Dept. of Astrophysical and Planetary Sciences, CU Boulder（科罗拉多大学博尔德分校天体物理与行星科学系及JILA）；Dept. of Astronomy, University of Michigan（密歇根大学天文学系）；Center for Astrophysics — Harvard & Smithsonian（哈佛史密森尼天体物理中心）
How a Close-in Planet Protects its White Dwarf Host from Pollution
School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics, Ministry of Education（教育部现代天文与天体物理重点实验室）；School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）
Fates of the sub-stellar objects (FOSSO) II. Evidence for Suppression of Metal Pollution in White Dwarfs by Close Substellar Companions
School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）；CSST Science Center for the Guangdong-Hong Kong-Macau Great Bay Area, Sun Yat-sen University（中山大学粤港澳大湾区子午线工程科学中心）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）
Pre-MAP Search for Transiting Objects Orbiting White Dwarfs
白矮星大气中的金属污染可能是行星物体的吸积残余物。在发现了经过WD 1145+017的解体行星天体（Vanderburg et al. 2015）之后，华盛顿大学天文学预科项目（Pre-MAP）的本科生受到启发，收集最明亮的白矮星的测光，以寻找其他金属污染的白矮星周围的类似过境天体。之前的调查还没有发现一颗围绕白矮星运行的凌日行星，但白矮星仍然是寻找小型岩石行星材料的有吸引力的目标。由于一颗典型的白矮星是地球大小的，因此地球大小的行星的凌日深度可能超过50%，因此即使是低信噪比的测光也有机会发现凌日物质。我们在SDSS DR 10白矮星目录中发现了明亮的、北方的、金属污染的白矮星，并在阿帕奇角天文台用天体物理研究联合会小孔径望远镜（ARCSAT）的0.5米望远镜观测了五个目标。ARCSAT测光有足够的精度来探测短轨道周期的月球大小或更大的物体，尽管没有探测到这些目标的行星。我们期待着可能发现行星围绕白矮星运行的调查，如美国宇航局的TESS，欧空局的PLATO和Evryscope。
WD 1054-226 revisited: a stable transiting debris system
Observatoire Astronomique de l’Université de Genève（日内瓦大学天文台）；Lund University（隆德大学）；Universidad de La Laguna (ULL)（拉帕鲁纳大学）；Instituto de Astrofísica de Canarias (IAC)（加那利天体物理研究所）；McDonald Observatory（麦克唐纳天文台）；The University of Tokyo（东京大学）
The MIRI Excess around Degenerates (MEAD) Survey II: A Probable Planet detected via IR Excess around WD 0644+025
University of Oklahoma（俄克拉荷马大学）；Space Telescope Science Institute（太空望远镜科学研究所）；Smith College（史密斯学院）；Université de Montréal（蒙特利尔大学）；University of California San Diego（加利福尼亚大学圣地亚哥分校）；Smithsonian Astrophysical Observatory（史密森尼天体物理台）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；Wesleyan University（卫斯理安大学）
