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arXiv 1503.03173astro-ph.EP
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根据斯皮策和后续观察的组合估计开普勒候选者的低假阳性率

Low False-Positive Rate of Kepler Candidates Estimated From A Combination Of Spitzer And Follow-Up Observations

Jean-Michel Désert, David Charbonneau, Guillermo Torres, Francois Fressin, Sarah Ballard, Stephen T. Bryson, Heather A. Knutson, Natalie M. Batalha, William J. … 展开作者

Jean-Michel Désert, David Charbonneau, Guillermo Torres, Francois Fressin, Sarah Ballard, Stephen T. Bryson, Heather A. Knutson, Natalie M. Batalha, William J. Borucki, Timothy M. Brown, Drake Deming, Eric B. Ford, Jonathan J. Fortney, Ronald L. Gilliland, David W. Latham, Sara Seager

摘要:

NASA的开普勒任务已经提供了数千颗过境行星候选者,但只有一小部分被确认为真正的行星。因此,关于这些候选者的最基本问题是真正行星的比例。估计整个开普勒样本的误报率对于推导行星出现率是必要的。我们提出的结果,从两个大的观测活动,进行了斯皮策望远镜在开普勒任务。这些观测致力于估计开普勒候选者中的假阳性率(FPR)。我们选择了一个子样本的51名候选人,跨越广泛的恒星,轨道和行星参数空间,我们观察他们的凌日与斯皮策在4.5微米。我们使用这些观测来测量候选者的过境深度和红外强度。一个依赖于带通的深度警告我们,一个可能是观测到的日食的来源的混合星的潜在存在:一个假阳性的场景。对于大多数候选者(85%),与开普勒测量的过境深度与斯皮策测量的深度一致,预期行星物体,而我们发现,最不一致的测量是由于存在未解决的恒星稀释测光。斯皮策限制自己的产量FPR在5- 40%之间,取决于KOI。通过考虑开普勒场恒星的人口,并结合后续观测(成像)时,我们发现,我们的样本的整体FPR是低的。在3 sigma的置信水平下,我们样本的FPR的测量上限为8.8%。这一观测结果使用了开普勒观测没有研究过的行星凌日信号的消色差特性,提供了一个独立的迹象,表明开普勒的假阳性率很低。

英文摘要:

(Abridged) NASA's Kepler mission has provided several thousand transiting planet candidates, yet only a small subset have been confirmed as true planets. Therefore, the most fundamental question about these candidates is the fraction of bona fide planets. Estimating the rate of false positives of the overall Kepler sample is necessary to derive the planet occurrence rate. We present the results from two large observational campaigns that were conducted with the Spitzer telescope during the the Kepler mission. These observations are dedicated to estimating the false positive rate (FPR) amongst the Kepler candidates. We select a sub-sample of 51 candidates, spanning wide ranges in stellar, orbital and planetary parameter space, and we observe their transits with Spitzer at 4.5 microns. We use these observations to measures the candidate's transit depths and infrared magnitudes. A bandpass-dependent depth alerts us to the potential presence of a blending star that could be the source of the observed eclipse: a false-positive scenario. For most of the candidates (85%), the transit depths measured with Kepler are consistent with the depths measured with Spitzer as expected for planetary objects, while we find that the most discrepant measurements are due to the presence of unresolved stars that dilute the photometry. The Spitzer constraints on their own yield FPRs between 5-40%, depending on the KOIs. By considering the population of the Kepler field stars, and by combining follow-up observations (imaging) when available, we find that the overall FPR of our sample is low. The measured upper limit on the FPR of our sample is 8.8% at a confidence level of 3 sigma. This observational result, which uses the achromatic property of planetary transit signals that is not investigated by the Kepler observations, provides an independent indication that Kepler's false positive rate is low.

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