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首页> 外文期刊>The Astrophysical journal >ESTIMATES OF THE PLANET YIELD FROM GROUND-BASED HIGH-CONTRAST IMAGING OBSERVATIONS AS A FUNCTION OF STELLAR MASS
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ESTIMATES OF THE PLANET YIELD FROM GROUND-BASED HIGH-CONTRAST IMAGING OBSERVATIONS AS A FUNCTION OF STELLAR MASS

机译:基于地面高对比度成像观测的行星产量估算值(基于星体质量)

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We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, β Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple formation mechanisms are at work. Upon relaxing our assumption that planets in ultra-wide (a 100 AU) orbits resemble the RV sample, our simulations suggest that the companions found orbiting late-type stars (AB Pic, 1RXSJ1609, GSC 06214, etc.) are consistent with a formation channel distinct from that of RV planets. These calculations explain why planets have thus far been imaged preferentially around A-stars and K-, M-stars, but no spectral types in between, despite concerted efforts targeting F-, G-stars.
机译:我们使用蒙特卡洛模拟来估算使用当前和即将推出的高对比度成像仪器可以直接在太阳附近探测到的太阳系外行星的数量。我们的计算考虑了控制对行星成像的可能性的重要因素,包括太阳附近恒星的统计特性,恒星与行星特性之间的相关性,观测效应以及选择标准。我们考虑了几种不同的,有偏见的和无偏见的地面勘测,并将产生的行星产量表示为恒星质量的函数。根据年青和视觉亮度来选择目标,我们发现要重现迄今为止的高对比度成像结果(即HR 8799,βPic),就需要恒星质量与行星属性之间有很强的相关性。利用最近的径向速度(RV)调查得出的气体巨型行星发生率的经验发现,我们的模拟结果表明,将多普勒行星种群的天真外推到高对比度仪器可及的半长轴上,这在模拟与使用当今的对比水平进行观察。除了本质上还年轻,足够明亮以用作自适应光学校正的信标外,A星还具有很高的行星发生率和形成宽轨道大质量行星的倾向,使其成为理想的目标。造成大质量恒星周围产生大量可探测行星的相同效应共同减少了低质量恒星的轨道数量。但是,在年轻的恒星群的情况下,目标的年龄大致相同并且位于大致相同的距离,由于与少量统计数据有关的观测偏差,MK恒星可以轻松地主导探测次数。在这种特殊情况下,低质量恒星产生最多的行星探测的程度取决于是否有多种形成机制起作用。在放宽我们认为超宽(> 100 AU)轨道上的行星类似于RV样本的假设后,我们的模拟表明,同伴发现了绕后型恒星(AB Pic,1RXSJ1609,GSC 06214等)运行的轨道与形成通道不同于RV行星。这些计算解释了为何尽管迄今为止针对F和G恒星进行了共同努力,但为什么到目前为止对A恒星和K恒星,M恒星进行了优先成像,而两者之间却没有光谱类型。

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