text: 373,42,1309224864276975616,4365927557,Dr. Jake Turner 🌅,"****New Paper Alert**  Today my group at @Cornell @CSInst (@AstroAndrew123, @DrRayJay, & I) published a new paper using @NASA_TESS data  ""TESS Observations of the Hot Jupiter Exoplanet XO-6b: No Evidence of Transit Timing Variations""  <LINK> THREAD 1/8 <LINK> XO-6b is a typical hot Jupiter that orbits a F5V-type star. Previous ground-based observations by Garai et al. 2020 (<LINK>) find transit timing variations (TTvs) with an amplitude of 14 min & period of 450 days 2/8 <LINK> Inspired by the possible TTVs from XO-6b, we looked at the system with NASA's TESS (@NASA_TESS) mission.  TESS is perfect for this study because it has really good photometric and timing precision.  More on the timing verification from TESS: <LINK> 2/8 <LINK> The @NASA_TESS light curves of XO-6b were exquisite in precision allowing for us to characterize the system with much greater detail than ever before. 3/8 <LINK> We fit the individual and combined light curves with EXOMOP, a transit fitting code I developed in my PhD. All the fits individual fits were consistent with each other.  More details on code: <LINK> 4/8 <LINK> The main result of our paper: - We find no evidence for TTVs: we can rule out TTVs &gt; 2.5 minutes at the 3σ level. - We rule out the previous claim of TTVs by 10σ 5/8 <LINK> The cause of the tension between our results & those of Garai et al. (2020) is not clear but it may be due to unknown timing errors in their ground-based data.  - A few of the smaller TTVs could be related to barycentric corrections, the larger ones must have other causes. 6/8 <LINK> Careful absolute telescope clock calibrations are important to adequately schedule future atmospheric characterization observations on JWST, etc.. Our study shows we need to be careful cause ground-based telescopes will definitely play a role (see <LINK>) 7/8 In conclusion: Our findings highlight @NASA_TESS's capabilities for robust follow-up, and confirm that TTVs are rarely seen in hot Jupiters, unlike is the case with small planets.  You can find the paper free here: <LINK> 8/8",https://arxiv.org/abs/2009.10781,"From previous ground-based observations, the hot Jupiter exoplanet XO-6b was reported to exhibit apparently periodic transit timing variations (TTVs), with a semi-amplitude of 14 minutes and a period of about 450 days. These variations were interpreted as being due to a resonant perturbation between XO-6b and a hitherto unknown low-mass planet orbiting the same star. To understand this enigmatic planetary system better, we analysed three sectors of data, spanning over seven months, from the Transiting Exoplanet Survey Satellite (TESS), which produces high-quality light curves that are well suited to characterizing exoplanets and searching for TTVs. Here we present an updated orbital period of 3.7649893 $\pm$ 0.0000037 days and a transit epoch of 2456652.7157 $\pm$ 0.0022 BJD$_{TDB}$. The planetary parameters we report, while consistent with their discovery values, have greatly improved precision. Notably, we find no evidence for TTVs: we can rule out TTVs $\gtrsim$ 2.5 minutes at the 3$\sigma$ level. Therefore, the TESS data have sufficient precision and time baseline to reveal readily the previously reported TTVs of approximately 10 minutes. Our findings highlight TESS's capabilities for robust follow-up, and confirm that TTVs are rarely seen in hot Jupiters, unlike is the case with small planets. ","TESS Observations of the Hot Jupiter Exoplanet XO-6b: No Evidence of