分类： 天文学 >> 天文学 提交时间： 2023-02-19
Su-Su Shan
Fan Yang
You-Jun Lu
Xing Wei
Wen-Wu Tian
Hai-Yan Zhang
Rui Guo
Xiao-Hong Cui
Ai-Yuan Yang
Bo Zhang
Ji-Feng Liu
摘要： A precise transit ephemeris serves as the premise for follow-up exoplanet observations. We compare TESS Objects of Interest (TOI) transit timings of 262 hot Jupiters with the archival ephemeris and find 31 of them having TOI timing offsets, among which WASP-161b shows the most significant offset of -203.7$\pm$4.1 minutes. The median value of these offsets is 17.8 minutes, equivalent to 3.6 $\sigma$. We generate TESS timings in each sector for these 31 hot Jupiters, using a self-generated pipeline. The pipeline performs photometric measurements to TESS images and produces transit timings by fitting the light curves. We refine and update the previous ephemeris, based on these TESS timings (uncertainty $\sim$ 1 minute) and a long timing baseline ($\sim 10$ years). Our refined ephemeris gives the transit timing at a median precision of 0.82 minutes until 2025 and 1.21 minutes until 2030. We regard the timing offsets mainly originating from the underestimated ephemeris uncertainty. All the targets with timing offset larger than 10$\sigma$ present earlier timings than the prediction, which cannot be due to underestimated ephemeris uncertainty, apsidal precision, or R$\o$mer effect as those effects should be unsigned. For some particular targets, timing offsets are likely due to tidal dissipation. Our sample leads to the detection of period decaying candidates of WASP-161b and XO-3b reported previously.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Zhen-Zhao Tao
Hai-Chen Zhao
Tong-Jie Zhang
Vishal Gajjar
Yan Zhu
You-Ling Yue
Hai-Yan Zhang
Wen-Fei Liu
Shi-Yu Li
Jian-Chen Zhang
Cong Liu
Hong-Feng Wang
Ran Duan
Lei Qian
Cheng-Jin Jin
Di Li
Andrew Siemion
Peng Jiang
Dan Werthime
Jeff Cobb
摘要： As a major approach to looking for life beyond the Earth, the search for extraterrestrial intelligence (SETI) is committed to detecting technosignatures such as engineered radio signals that are indicative of technologically capable life. In this paper, we report a targeted SETI campaign employing an observation strategy named multi-beam coincidence matching (MBCM) at the Five-hundred-meter Aperture Spherical radio Telescope (FAST) towards 33 known exoplanet systems, searching for ETI narrow-band drifting signals across 1.05-1.45 GHz in two orthogonal linear polarization directions separately. A signal at 1140.604 MHz detected from the observation towards Kepler-438 originally peaked our interest because its features are roughly consistent with assumed ETI technosignatures. However, evidences such as its polarization characteristics are almost able to eliminate the possibility of an extraterrestrial origin. Our observations achieve an unprecedented sensitivity since the minimum equivalent isotropic radiated power (EIRP) we are able to detect reaches 1.48 x10^9 W.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Su-Su Shan
Fan Yang
You-Jun Lu
Xing Wei
Wen-Wu Tian
Hai-Yan Zhang
Rui Guo
Xiao-Hong Cui
Ai-Yuan Yang
Bo Zhang
Ji-Feng Liu
摘要： A precise transit ephemeris serves as the premise for follow-up exoplanet observations. We compare TESS Objects of Interest (TOI) transit timings of 262 hot Jupiters with the archival ephemeris and find 31 of them having TOI timing offsets, among which WASP-161b shows the most significant offset of -203.7$\pm$4.1 minutes. The median value of these offsets is 17.8 minutes, equivalent to 3.6 $\sigma$. We generate TESS timings in each sector for these 31 hot Jupiters, using a self-generated pipeline. The pipeline performs photometric measurements to TESS images and produces transit timings by fitting the light curves. We refine and update the previous ephemeris, based on these TESS timings (uncertainty $\sim$ 1 minute) and a long timing baseline ($\sim 10$ years). Our refined ephemeris gives the transit timing at a median precision of 0.82 minutes until 2025 and 1.21 minutes until 2030. We regard the timing offsets mainly originating from the underestimated ephemeris uncertainty. All the targets with timing offset larger than 10$\sigma$ present earlier timings than the prediction, which cannot be due to underestimated ephemeris uncertainty, apsidal precision, or R$\o$mer effect as those effects should be unsigned. For some particular targets, timing offsets are likely due to tidal dissipation. Our sample leads to the detection of period decaying candidates of WASP-161b and XO-3b reported previously.
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