我们确定在一个均匀的方式的金属丰度和个人的丰度的大样本的演化恒星,有和没有已知的行星同伴。我们的方法是基于高分辨率阶梯光谱的分析。金属丰度分布表明,拥有行星的巨恒星并不优先富含金属,其丰度模式与没有已知行星伴星的巨恒星相似。然而,我们已经发现,在这个样本中,金属丰度分布和恒星质量之间有很强的关系。结果表明,具有行星的质量较小的巨星(M < 1.5 Msun)并不富含金属,但是,具有行星的质量较大的(M > 1.5 Msun)、年龄小于2 Gyr的巨星样品的金属丰度要高于没有行星的类似恒星样品。至于其他化学元素,质量域M < 1.5 Msun的有行星和没有行星的巨星显示出类似的丰度模式。然而,质量M > 1.5 Msun的行星和非行星宿主在某些元素的丰度上显示出差异,特别是Na,Co和Ni。此外,我们发现样本的次巨星的行星是金属丰富的显示类似的金属丰度主序星主机。质量域M < 1.5 Msun的巨行星宿主没有金属富集的事实很难解释。鉴于这些恒星与次巨星和主序星的恒星参数相似,低质量巨星缺乏富含金属的特征可以解释为,如果起源于主序星中的污染场景,当恒星完全对流时被抹去。然而,没有物理上的理由说明它应该对质量为M1.5 Msun的巨星起作用< 1.5 Msun but is not observed for giants with M >。
英文摘要:
We determine in a homogeneous way the metallicity and individual abundances of a large sample of evolved stars, with and without known planetary companions. Our methodology is based on the analysis of high-resolution echelle spectra. The metallicity distributions show that giant stars hosting planets are not preferentially metal-rich having similar abundance patterns to giant stars without known planetary companions. We have found, however, a very strong relation between the metallicity distribution and the stellar mass within this sample. We show that the less massive giant stars with planets (M < 1.5 Msun) are not metal rich, but, the metallicity of the sample of massive (M > 1.5 Msun), young (age < 2 Gyr) giant stars with planets is higher than that of a similar sample of stars without planets. Regarding other chemical elements, giant stars with and without planets in the mass domain M < 1.5 Msun show similar abundance patterns. However, planet and non-planet hosts with masses M > 1.5 Msun show differences in the abundances of some elements, specially Na, Co, and Ni. In addition, we find the sample of subgiant stars with planets to be metal rich showing similar metallicities to main-sequence planet hosts. The fact that giant planet hosts in the mass domain M < 1.5 Msun do not show metal-enrichment is difficult to explain. Given that these stars have similar stellar parameters to subgiants and main-sequence planet hosts, the lack of the metal-rich signature in low-mass giants could be explained if originated from a pollution scenario in the main sequence that gets erased as the star become fully convective. However, there is no physical reason why it should play a role for giants with masses M < 1.5 Msun but is not observed for giants with M > 1.5 Msun.
A Dichotomy of the Mass-Metallicity Relation of Exoplanetary Atmospheres Demarcated by their Birthplace
Division of Science, National Astronomical Observatory of Japan(日本国立天文台科学部);Graduate Institute for Advanced Studies, SOKENDAI(综合研究大学院大学);Astrobiology Center(天体生物学中心);Department of Earth and Planetary Science, The University of Tokyo(东京大学地球行星科学系);Department of Earth and Planetary Sciences, Institute of Science Tokyo(东京科学大学地球行星科学系);UTokyo Organization for Planetary Space Science (UTOPS), University of Tokyo(东京大学宇宙行星科学研究组织);Kapteyn Astronomical Institute, University of Groningen(格罗宁根大学卡普坦天文研究所)
Can we really detect planets around evolved massive stars?
大质量恒星周围行星的发现对于理解行星形成和演化是如何受到不同恒星环境的制约是很重要的。然而,目前的行星搜索调查未能发现大质量演化恒星周围的行星。这种行星的缺乏可能是这些天体周围行星形成的特殊性的结果。另一种可能是,随着恒星的演化,恒星抖动的增加可能会阻碍对演化中的大质量恒星周围行星的探测。在这个项目中,我们的目标是疏散星团中进化恒星周围的行星,其中大多数质量超过2 M $_\odot$。我们提出了三个对象的情况下,长期(即年)和高振幅RV信号可能恒星起源模仿行星的存在。
Atmospheric metal enrichment (i.e., elements heavier than helium, also called "metallicity") is a key diagnostic of the formation of giant planets. The giant planets of the solar system exhibit an inverse relationship between mass and both their bulk metallicities and atmospheric metallicities. Extrasolar giant planets also display an inverse relationship between mass and bulk metallicity. However, there is significant scatter in the relationship and it is not known how atmospheric metallicity correlates with either planet mass or bulk metallicity. Here we show that the Saturn-mass exoplanet H…
New and updated stellar parameters for 71 evolved planet hosts. On the metallicity - giant planet connection
目前仍有争议的是,著名的矮恒星金属丰度-巨行星相关性是否也适用于巨恒星。因此,精确的金属丰度非常重要。不同的方法可以提供不同的结果,导致行星宿主分析的差异。为了研究不同的分析方法对演化恒星金属丰度标度的影响,我们比较了不同的铁谱线列表,用于演化恒星的大气参数推导。因此,我们使用了71颗演化恒星的样本。有了这些新的均匀参数,我们重新审视了演化恒星的金属丰度-巨行星联系。基于局部热力学平衡(LTE)下的Kurucz模式,通过MOOG程序进行光谱分析,以获得大气参数。使用了两个不同的铁线列表集,一个是一般的冷FGK恒星,另一个是巨大的FGK恒星。使用Padova模型通过等时线拟合计算质量。然后对演化恒星和红巨星的各种不同样本的金属丰度分布进行了科尔莫戈罗夫-斯米尔诺夫检验(KS检验)。所有的参数都可以用一个专门为冷的和类似太阳的恒星设计的线列表集进行比较,以提供更准确的温度。使用此线路列表集导出的所有参数均为首选,因此可用于未来分析。我们发现,进化的行星宿主比拥有巨行星的矮星更缺乏金属。然而,在寻找行星的巨大恒星样本中存在偏见。由于颜色的限制,富含金属的低重力恒星被排除在样本之外,这使得很难将矮星与巨星进行比较。此外,相对于没有行星的红巨星,没有发现有行星的红巨星($\log g < 3.0$ \,dex)的金属丰度增强。
Architectures of Planetary Systems II: Trends with Host Star Mass and Metallicity
The Catholic University of America(天主教大学);NASA Goddard Space Flight Center(NASA戈达德太空飞行中心);Center for Research and Exploration in Space Science and Technology, NASA/GSFC(NASA/戈达德太空飞行中心空间科学与技术研究与探索中心);University of Wisconsin-Madison(威斯康星大学麦迪逊分校);University of Michigan(密歇根大学)
No correlation between the Transit-Depth Metallicity of Kepler gas giant confirmed and candidates planets: A Bayesian Approach
以前试图研究开普勒气体巨行星的凌日深度和恒星金属丰度之间的相关性,导致了不同的结果。据报道,开普勒(Q1-Q12)气态巨行星候选者与开普勒输入星表(KIC)中的[Fe/H]值和半径估计为5- 20 R $_\odot$之间存在微弱的显著负相关。随着最后一个开普勒目录(Q1-Q17)的发布,我们现在拥有最大的系外行星均匀样本。这使得能够对这种相关性进行可靠的统计分析。在目前的工作中,我们修改这种相关性,贝叶斯框架内,两个大的同质样本:确认和完成。我们扩展了一个层次模型,以考虑所研究的样本中的假阳性。我们的统计分析表明凌日深度与恒星金属丰度之间没有相关性。我们没有发现这种相关性的证据,这一事实将对行星形成理论和巨行星的内部结构产生影响。
Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. III. HD 5583 and BD+15 2375 - two cool giants with warm companions
演化恒星是理解行星形成机制对恒星质量的依赖性和深入探索恒星-行星相互作用机制的关键。在过去的十年中,我们已经监测了大约1000颗进化恒星的径向速度变化,以寻找宾夕法尼亚州立大学-托伦天文学行星搜索中心的Hobby-Eberly望远镜下的低质量同伴。根据TAPAS项目,在3.6米国家伽利略望远镜上使用HARPS-N跟踪了需要更高RV精度测量的选定潜在候选者。我们的目标是探测演化恒星周围的行星系,以便能够对这些系统的频率和内在性质进行合理的统计,并对选定的行星系进行深入研究,并提供恒星-行星相互作用过程的证据。对于HD 5583,我们使用Hobby-Eberly望远镜(HET)在2313天内收集了14个时期的精确RV测量数据,并在976天内收集了22个时期的超精确HARPS-N数据。对于BD+15 2375,我们收集了超过3286天的24个HET数据和超过902天的25个HARPS-S数据。我们报告发现了两个行星质量物体绕两颗演化的红巨星运行:HD~5583在0.529天文单位处有一个近圆轨道的伴星,它的轨道半径为5.78 M,轨道半径为$_{J}$(e=0.076),是用RV技术探测到的一颗巨星最近的伴星,BD+15~2735,它的m sin i= 1.06 M $_{J}$保持着迄今为止发现的最轻行星绕演化恒星运行的记录(在圆e=0.001,0.576 AU的轨道上)。这是TAPA…
Giant planets on short-period orbits are predicted to be inflated and eventually engulfed by their host stars. However, the detailed timescales and stages of these processes are not well known. Here we present the discovery of three hot Jupiters (P $<$ 10 d) orbiting evolved, intermediate-mass stars ($M_\star$ $\approx$ 1.5 M$_\odot$, 2 R$_\odot$ $<$ $R_\star < $ 5 R$_\odot$). By combining \tess photometry with ground-based photometry and radial velocity measurements, we report masses and radii for these three planets between 0.4 and 1.8 M$_\mathrm{J}$ and 0.8 and 1.8 R$_\mathrm{J}$. \planet h…
A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
We report the detection of a double planetary system around the evolved intermediate-mass star HD 47366 from precise radial-velocity measurements at Okayama Astrophysical Observatory, Xinglong Station, and Australian Astronomical Observatory. The star is a K1 giant with a mass of 1.81+-0.13M_sun, a radius of 7.30+-0.33R_sun, and solar metallicity. The planetary system is composed of two giant planets with minimum mass of 1.75^{+0.20}_{-0.17}Mjup and 1.86^{+0.16}_{-0.15}Mjup, orbital period of 363.3^{+2.5}_{-2.4} d and 684.7^{+5.0}_{-4.9} d, and eccentricity of 0.089^{+0.079}_{-0.060} and 0.278…
Uniform Metallicity Measurements of M Dwarf Planet Hosts Support Metallicity-Dependent Sub-Neptune Formation
McMaster University(麦克马斯特大学);University of California, Berkeley(加州大学伯克利分校);California Institute of Technology(加州理工学院);San Francisco State University(旧金山州立大学);Georgia State University(佐治亚州立大学);RECONS Institute(RECONS研究所);Flatiron Institute(平顿研究所)
We report the discovery of a triple-giant-planet system around an evolved star HD 184010 (HR 7421, HIP 96016). This discovery is based on observations from Okayama Planet Search Program, a precise radial velocity survey, undertaken at Okayama Astrophysical Observatory between 2004 April and 2021 June. The star is K0 type and located at beginning of the red-giant branch. It has a mass of $1.35_{-0.21}^{+0.19} M_{\odot}$, a radius of $4.86_{-0.49}^{+0.55} R_{\odot}$, and a surface gravity $\log g$ of $3.18_{-0.07}^{+0.08}$. The planetary system is composed of three giant planets in a compact con…
While it is well established that giant-planet occurrence rises rapidly with host star metallicity, it is not yet clear if small-planet occurrence around late-type dwarf stars depends on host star metallicity. Using the Kepler Data Release 25 planet candidate list and its completeness data products, we explore planet occurrence as a function of metallicity in the Kepler field's late-type dwarf stellar population. We find that planet occurrence increases with metallicity for all planet radii $R_{\mathrm{p}}$ down to at least $R_{\mathrm{p}}\approx2~R_{\oplus}$ and that in the range $2~R_{\oplus…
We present a basic, fast, and flexible planet formation model, called SimAb (Simulating Abundances), to form giant planets and study their primary atmospheric composition soon after their formation. In SimAb we introduce parameters to simplify the assumptions about the complex physics involved in the formation of a planet. This approach allows us to trace and understand the influence of complex physical processes on the formed planets. We focus on the C/O ratio and the metallicity of the planetary atmosphere as an indicator of their compositions. We show that the initial protoplanet core mass …
The fate of planets around rapidly evolving stars is not well understood. Previous studies have suggested that relative to the main sequence population, planets transiting evolved stars ($P$ $<$ 100 d) tend to have more eccentric orbits. Here we present the discovery of TOI-4582 b, a 0.94 $\pm$ 0.12 R$_\mathrm{J}$, 0.53 $\pm$ 0.05 M$_\mathrm{J}$ planet orbiting an intermediate-mass subgiant star every 31.034 days. We find that this planet is also on a significantly eccentric orbit ($e$ = 0.51 $\pm$ 0.05). We then compare the population of planets found transiting evolved (log$g$ $<$ 3.8) stars…