- ID:
- ivo://CDS.VizieR/J/A+A/658/A170
- Title:
- TRAPPIST-1 best-fit parameters
- Short Name:
- J/A+A/658/A170
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We analyze solutions drawn from the recently published posterior distribution of the TRAPPIST-1 system, which consists of seven Earth-size planets appearing to be in a resonant chain around a red dwarf. We show that all the planets are simultaneously in 2-planet and 3-planet resonances, apart from the innermost pair for which the 2-planet resonant angles circulate. By means of a frequency analysis, we highlight that the transit-timing variation (TTV) signals possess a series of common periods varying from days to decades, which are also present in the variations of the dynamical variables of the system. Shorter periods (e.g., the TTVs characteristic timescale of 1.3yr) are associated with 2-planet mean-motion resonances, while longer periods arise from 3-planet resonances. By use of N-body simulations with migration forces, we explore the origin of the resonant chain of TRAPPIST-1 and find that for particular disc conditions, a chain of resonances -- similar to the observed one -- can be formed which accurately reproduces the observed TTVs. Our analysis suggests that while the 4-yr collected data of observations hold key information on the 2-planet resonant dynamics, further monitoring of TRAPPIST-1 will soon provide signatures of three-body resonances, in particular the 3.3 and 5.1yr periodicities expected for the current best-fit solution. Additional observations would help to assess whether the innermost pair of planets is indeed resonant (its proximity to the 8:5 resonance being challenging to explain), and therefore give additional constraints on formation scenarios.
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- ID:
- ivo://CDS.VizieR/J/A+A/658/A133
- Title:
- TRAPPIST-1 h NIR spectrum
- Short Name:
- J/A+A/658/A133
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The TRAPPIST-1 planetary system is favorable for transmission spectroscopy and offers the unique opportunity to study rocky-planets with possibly non-primary envelopes. We present here the transmission spectrum of the seventh planet of the TRAPPIST-1 system, TRAPPIST-1 h (R_P_=0.752R_{Earth}_, Teq=173K) using Hubble Space Telescope (HST), Wide Field Camera 3 Grism 141 (WFC3/G141) data. Our purpose is to reduce the HST observations of the seventh planet of TRAPPIST-1 system and by testing simple atmospheric hypothesis put new constraint on the composition and the nature of the planet. First we extracted and corrected the raw data to obtain a transmission spectrum in the Near-IR band (1.1-1.7um). TRAPPIST-1 is a cold M-dwarf and its activity could affect the transmission spectrum. We correct for stellar modulations using three different stellar contamination models, while some fit better the data, they are statistically not significant and the conclusion remains unchanged concerning the presence or not of an atmosphere. Finally, using a Bayesian atmospheric retrieval code we put new constraints on the atmosphere composition of TRAPPIST-1h. According to the retrieval analysis, there is no evidence of molecular absorption in the Near-InfraRed (NIR) spectrum. This suggests the presence of a high cloud deck or a layer of photochemical hazes in a primary atmosphere or a secondary atmosphere dominated by heavy species like nitrogen. This result could even be the consequence of the lack of an atmosphere as the spectrum is better fitted using a flat-line. Variations of transit depth around 1.3um are likely due to remaining scattering noise and results are not improved while changing the spectral resolution. TRAPPIST-1 h has probably lost its atmosphere or possesses a layer of clouds and hazes blocking the NIR signal. We can not distinguish yet between a primary cloudy or a secondary clear envelope using HST/WFC3 data but we can reject, in most cases with more than 3{sigma} confidence, the hypothesis of a clear atmosphere dominated by hydrogen and helium. By testing forced secondary atmospheric scenario, we find that a CO-rich atmosphere (i.e with a volume mixing ratio of 0.2) is one of the best fit to the spectrum with a Bayes Factor of 1.01 corresponding to a 2.1{sigma} detection.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A112
- Title:
- TRAPPIST-1 transit timings
- Short Name:
- J/A+A/640/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With more than 1000 hours of observation from Feb 2016 to Oct 2019, the Spitzer Exploration Program Red Worlds (ID: 13067, 13175 and 14223) exclusively targeted TRAPPIST-1, a nearby (12pc) ultracool dwarf star, finding that it is orbited by seven transiting Earth-sized planets. At least three of these planets orbit within the classical habitable zone of the star, and all of them are well-suited for a detailed atmospheric characterization with the upcoming JWST. The main goals of the Spitzer Red Worlds program were (1) to explore the system for new transiting planets, (2) to intensively monitor the planets' transits to yield the strongest possible constraints on their masses, sizes, compositions, and dynamics, and (3) to assess the infrared variability of the host star. In this paper, we present the global results of the project. We analyzed 88 new transits and combined them with 100 previously analyzed transits, for a total of 188 transits observed at 3.6 or 4.5um. For a comprehensive study, we analyzed all light curves both individually and globally. We also analyzed 29 occultations (secondary eclipses) of planet b and eight occultations of planet c observed at 4.5um to constrain the brightness temperatures of their daysides. We identify several orphan transit-like structures in our Spitzer photometry, but all of them are of low significance. We do not confirm any new transiting planets. We do not detect any significant variation of the transit depths of the planets throughout the different campaigns. Comparing our individual and global analyses of the transits, we estimate for TRAPPIST-1 transit depth measurements mean noise floors of ~35 and 25ppm in channels 1 and 2 of Spitzer/IRAC, respectively. We estimate that most of this noise floor is of instrumental origins and due to the large inter-pixel inhomogeneity of IRAC InSb arrays, and that the much better interpixel homogeneity of JWST instruments should result in noise floors as low as 10ppm, which is low enough to enable the atmospheric characterization of the planets by transit transmission spectroscopy. Our analysis reveals a few outlier transits, but we cannot conclude whether or not they correspond to spot or faculae crossing events. We construct updated broadband transmission spectra for all seven planets which show consistent transit depths between the two Spitzer channels. Although we are limited by instrumental precision, the combined transmission spectrum of planet b to g tells us that their atmospheres seem unlikely to be CH_4_-dominated. We identify and model five distinct high energy flares in the whole dataset, and discuss our results in the context of habitability. Finally, we fail to detect occultation signals of planets b and c at 4.5um, and can only set 3{sigma} upper limits on their dayside brightness temperatures (611K for b 586K for c).
- ID:
- ivo://CDS.VizieR/J/A+A/656/A88
- Title:
- TrES-5 photometric timeseries
- Short Name:
- J/A+A/656/A88
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The orbital motion of the transiting hot Jupiter TrES-5 b was reported to be perturbed by a planetary companion on a nearby orbit. Such compact systems do not frequently occur in nature, and learning their orbital architecture could shed some light on hot Jupiters' formation processes. We acquired fifteen new precise photometric time series for twelve transits of TrES-5 b between June 2019 and October 2020 using 0.9-2.0m telescopes. The method of precise transit timing was employed to verify the deviation of the planet from the Keplerian motion. Although our results show no detectable short-time variation in the orbital period of TrES-5 b and the existence of the additional nearby planet is not confirmed, the new transits were observed about two minutes earlier than expected. We conclude that the orbital period of the planet could vary in a long timescale. We found that the most likely explanation of the observations is the line-of-sight acceleration of the system's barycentre due to the orbital motion induced by a massive, wide-orbiting companion.
- ID:
- ivo://CDS.VizieR/J/AJ/161/24
- Title:
- TRICERATOPS predictions for 384 TOIs
- Short Name:
- J/AJ/161/24
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- We present TRICERATOPS, a new Bayesian tool that can be used to vet and validate TESS Objects of Interest (TOIs). We test the tool on 68 TOIs that have been previously confirmed as planets or rejected as astrophysical false positives. By looking in the false-positive probability (FPP)-nearby false-positive probability (NFPP) plane, we define criteria that TOIs must meet to be classified as validated planets (FPP<0.015 and NFPP<10^-3^), likely planets (FPP<0.5 and NFPP<10^-3^), and likely nearby false positives (NFPP>10^-1^). We apply this procedure on 384 unclassified TOIs and statistically validate 12, classify 125 as likely planets, and classify 52 as likely nearby false positives. Of the 12 statistically validated planets, 9 are newly validated. TRICERATOPS is currently the only TESS vetting and validation tool that models transits from nearby contaminant stars in addition to the target star. We therefore encourage use of this tool to prioritize follow-up observations that confirm bona fide planets and identify false positives originating from nearby stars.
- ID:
- ivo://CDS.VizieR/J/other/RAA/19.41
- Title:
- TTVs & linear ephemerides of Kepler exoplanets
- Short Name:
- J/other/RAA/19.4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined new linear ephemerides of transiting exoplanets using long-cadence de-trended data from quarters Q1 to Q17 of Kepler mission. We analysed TTV diagrams of 2098 extrasolar planets. The TTVs of 121 objects were excluded (because of insufficient data-points, influence of stellar activity, etc). Finally, new linear ephemerides of 1977 exoplanets from Kepler archive are presented. The significant linear trend was observed on TTV diagrams of approximately 35% of studied exoplanets. Knowing correct linear ephemeris is principal for successful follow-up observations of transits. Residual TTV diagrams of 64 analysed exoplanets shows periodic variation, 43 of these TTV planets were not reported yet.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A43
- Title:
- Two super-Earths orbiting TOI-402
- Short Name:
- J/A+A/627/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V=9.1 K1 dwarf also known as HD15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21R_{Earth}_, respectively. This star was observed prior to the TESS detection as part of the radial-velocity (RV) search for planets using the HARPS spectrometer, and 85 precise RV measurements were obtained before the launch of TESS over a period of 14 years. In this paper, we analyse the HARPS RV measurements in hand to confirm the planetary nature of these two signals. HD15337 happens to present a stellar activity level similar to the Sun, with a magnetic cycle of similar amplitude and RV measurements that are affected by stellar activity. By modelling this stellar activity in the HARPS radial velocities using a linear dependence with the calcium activity index log(R'_HK_), we are able, with a periodogram approach, to confirm the periods and the planetary nature of TOI-402.01 and TOI-402.02. We then derive robust estimates from the HARPS RVs for the orbital parameters of these two planets by modelling stellar activity with a Gaussian process and using the marginalised posterior probability density functions obtained from our analysis of TESS photometry for the orbital period and time of transit. By modelling TESS photometry and the stellar host characteristics, we find that TOI-402.01 and TOI-402.02 have periods of 4.75642+/-0.00021 and 17.1784+/-0.0016 days and radii of 1.70+/-0.06 and 2.52+/-0.11 (precision 3.6 and 4.2%), respectively. By analysing the HARPS RV measurements, we find that those planets are both super-Earths with masses of 7.20+/-0.81 and 8.79+/-1.68 (precision 11.3 and 19.1%), and small eccentricities compatible with zero at 2{sigma}. Although having rather similar masses, the radii of these two planets are very different, putting them on different sides of the radius gap. By studying the temporal evolution under X-ray and UV (XUV) driven atmospheric escape of the TOI-402 planetary system, we confirm, under the given assumptions, that photo-evaporation is a plausible explanation for this radius difference. Those two planets, being in the same system and therefore being in the same irradiation environment are therefore extremely useful for comparative exoplanetology across the evaporation valley and thus bring constraints on the mechanisms responsible for the radius gap.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A170
- Title:
- Ultracool dwarf K2 light curves
- Short Name:
- J/A+A/641/A170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the discovery of a planetary system around the ultracool dwarf TRAPPIST-1, there has been a surge of interest in such stars as potential planet hosts. Planetary systems around ultracool dwarfs represent our best chance of characterising temperate rocky-planet atmospheres with the James Webb Space Telescope. However, TRAPPIST-1 remains the only known system of its kind and the occurrence rate of planets around ultracool dwarfs is still poorly constrained. We seek to perform a complete transit search on the ultracool dwarfs observed by NASA's K2 mission, and use the results to constrain the occurrence rate of planets around these stars. We filter and characterise the sample of ultracool dwarfs observed by K2 by fitting their spectral energy distributions and using parallaxes from Gaia. We build an automatic pipeline to perform photometry, detrend the light curves, and search for transit signals. Using extensive injection-recovery tests of our pipeline, we compute the detection sensitivity of our search, and thus the completeness of our sample. We infer the planetary occurrence rates within a hierarchical Bayesian model (HBM) to treat uncertain planetary parameters.With the occurrence rate parametrised by a step-wise function, we present a convenient way to directly marginalise over the second level of our HBM (the planetary parameters). Our method is applicable generally and can greatly speed up inference with larger catalogues of detected planets. We detect one planet in our sample of 702 ultracool dwarfs: a previously validated mini-Neptune. We thus infer a mini-Neptune (2-4R_{Earth}_) occurrence rate of {eta}=0.20^+0.16^_0.11_ within orbital periods of 1-20 days. For super-Earths (1-2R_{Earth}_) and ice or gas giants (4-6R_{Earth}_) within 1-20 days, we place 95% credible intervals of {eta}<1.14 and {eta}<0.29, respectively. If TRAPPIST-1-like systems were ubiquitous, we would have a 96% chance of finding at least one.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A205
- Title:
- Ultra-hot Jupiter WASP-121b transits
- Short Name:
- J/A+A/635/A205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-hot Jupiters offer interesting prospects for expanding our theories on dynamical evolution and the properties of extremely irradiated atmospheres. In this context, we present the analysis of new optical spectroscopy for the transiting ultra-hot Jupiter WASP-121b. We first refine the orbital properties of WASP-121b, which is on a nearly polar (obliquity Psi^North^=88.1+/-0.25{deg} or Psi^South^=91.11+/-0.20{deg}) orbit, and exclude a high differential rotation for its fast-rotating (P<1.13-days), highly inclined (i*^North_=8.1^+3.0^_-2.6_{deg} or i*_South_=171.9^+2.5^_-3.4_{deg}) star. We then present a new method that exploits the reloaded Rossiter-McLaughlin technique to separate the contribution of the planetary atmosphere and of the spectrum of the stellar surface along the transit chord. Its application to HARPS transit spectroscopy of WASP-121b reveals the absorption signature from metals, likely atomic iron, in the planet atmospheric limb. The width of the signal (14.3+/-1.2km/s) can be explained by the rotation of the tidally locked planet. Its blueshift (-5.2+/-0.5km/s) could trace strong winds from the dayside to the nightside, or the anisotropic expansion of the planetary thermosphere.
- ID:
- ivo://CDS.VizieR/J/AJ/156/78
- Title:
- 44 validated planets from K2 Campaign 10
- Short Name:
- J/AJ/156/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 44 validated planets from the 10th observing campaign of the NASA K2 mission, as well as high-resolution spectroscopy and speckle imaging follow-up observations. These 44 planets come from an initial set of 72 vetted candidates, which we subjected to a validation process incorporating pixel-level analyses, light curve analyses, observational constraints, and statistical false positive probabilities. Our validated planet sample has median values of R_p_=2.2 R_{Earth}_, P_orb_=6.9 days, T_eq_=890 K, and J=11.2 mag. Of particular interest are four ultra-short period planets (P_orb_~<1 day), 16 planets smaller than 2 R_{Earth}_, and two planets with large predicted amplitude atmospheric transmission features orbiting infrared-bright stars. We also present 27 planet candidates, most of which are likely to be real and worthy of further observations. Our validated planet sample includes 24 new discoveries and has enhanced the number of currently known super-Earths (R_p_~1-2 R_{Earth}_), sub-Neptunes (R_p_~2-4 R_{Earth}_), and sub-Saturns (R_p_~4-8 R_{Earth}_) orbiting bright stars (J=8-10 mag) by ~4%, ~17%, and ~11%, respectively.
