- ID:
- ivo://CDS.VizieR/J/A+A/657/A102
- Title:
- Transit events of 4 extrasolar planets
- Short Name:
- J/A+A/657/A102
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Meter-sized ground-based telescopes are frequently used today for the follow-up of extrasolar planet candidates. While the transit signal of a Jupiter-sized object can typically be detected to a high level of confidence with small telescope apertures as well, the shallow transit dips of planets with the size of Neptune and smaller are more challenging to reveal. We employ new observational data to illustrate the photometric follow-up capabilities of meter-sized telescopes for shallow exoplanet transits. We describe in detail the capability of distinguishing the photometric signal of an exoplanet transit from an underlying trend in the light curve. The transit depths of the six targets we observed, Kepler-94b, Kepler-63b, K2-100b, K2-138b, K2-138c, and K2-138e, range from 3.9ppt down to 0.3ppt. For five targets of this sample, we provide the first ground-based photometric follow-up. The timing of three targets is precisely known from previous observations, and the timing of the other three targets is uncertain and we aim to constrain it. We detect or rule out the transit features significantly in single observations for the targets that show transits of 1.3ppt or deeper. The shallower transit depths of two targets of 0.6 and 0.8ppt were detected tentatively in single light curves, and were detected significantly by repeated observations. Only for the target of the shallowest transit depth of 0.3ppt were we unable to draw a significant conclusion despite combining five individual light curves. An injection-recovery test on our real data shows that we detect transits of 1.3ppt depth significantly in single light curves if the transit is fully covered, including out-of-transit data toward both sides, in some cases down to 0.7ppt depth. For Kepler-94b, Kepler-63b, and K2-100b, we were able to verify the ephemeris. In the case of K2-138c with a 0.6ppt deep transit, we were able to refine it, and in the case of K2-138e, we ruled out the transit in the time interval of more than +/-1.5{sigma} of its current literature ephemeris.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/506/3810
- Title:
- 7 transiting exoplanets CHEOPS light curves
- Short Name:
- J/MNRAS/506/3810
- Date:
- 03 Dec 2021 00:34:45
- Publisher:
- CDS
- Description:
- We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain combining multiple transits together. We reached the highest precision on the transit time of about 13-16s for the brightest target (WASP-38, G=9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G>=11 we obtained a timing precision of ~2min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/1107
- Title:
- Transiting planet candidates in HATNet field 205
- Short Name:
- J/ApJ/704/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-8b, a transiting planet with mass M_p_=1.52^+0.18^_-0.16_M_J_, radius R_p_=1.50^+0.08^_-0.06_R_J_, and photometric period P=3.076days. HAT-P-8b has a somewhat inflated radius for its mass, and a somewhat large mass for its period. The host star is a solar-metallicity F dwarf, with mass M_*_=1.28+/-0.04M_{sun}_ and R_*_=1.58^+0.08^_-0.06R_{sun}_. HAT-P-8b was initially identified as one of the 32 transiting-planet candidates in HATNet field G205. We describe the procedures that we have used to follow up these candidates with spectroscopic and photometric observations, and we present a status report on our interpretation for 28 of the candidates. Eight are eclipsing binaries with orbital solutions whose periods are consistent with their photometric ephemerides; two of these spectroscopic orbits are single-lined and six are double-lined.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A107
- Title:
- 231 transiting planets eccentricity and mass
- Short Name:
- J/A+A/602/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carried out a Bayesian homogeneous determination of the orbital parameters of 231 transiting giant planets (TGPs) that are alone or have distant companions; we employed differential evolution Markov chain Monte Carlo methods to analyse radial-velocity (RV) data from the literature and 782 new high-accuracy RVs obtained with the HARPS-N spectrograph for 45 systems over ~3 years. Our work yields the largest sample of systems with a transiting giant exoplanet and coherently determined orbital, planetary, and stellar parameters. We found that the orbital parameters of TGPs in non-compact planetary systems are clearly shaped by tides raised by their host stars. Indeed, the most eccentric planets have relatively large orbital separations and/or high mass ratios, as expected from the equilibrium tide theory. This feature would be the outcome of planetary migration from highly eccentric orbits excited by planet-planet scattering, Kozai-Lidov perturbations, or secular chaos. The distribution of {alpha}=a/a_R_, where a and a_R_ are the semi-major axis and the Roche limit, for well-determined circular orbits peaks at 2.5; this agrees with expectations from the high-eccentricity migration (HEM), although it might not be limited to this migration scenario. The few planets of our sample with circular orbits and {alpha}>5 values may have migrated through disc-planet interactions instead of HEM. By comparing circularisation times with stellar ages, we found that hot Jupiters with a<0.05au have modified tidal quality factors 10^5^<~Qp<~10^9^, and that stellar Qs>~10^6^-10^7^ are required to explain the presence of eccentric planets at the same orbital distance.
- ID:
- ivo://CDS.VizieR/J/AJ/157/218
- Title:
- Transiting planets near the snow line from Kepler
- Short Name:
- J/AJ/157/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive catalog of cool (period P>~2 yr) transiting planet candidates in the 4 yr light curves from the prime Kepler mission. Most of the candidates show only one or two transits and have largely been missed in the original Kepler Object of Interest catalog. Our catalog is based on all known such candidates in the literature, as well as new candidates from the search in this paper, and provides a resource to explore the planet population near the snow line of Sun-like stars. We homogeneously performed pixel-level vetting, stellar characterization with Gaia parallax and archival/Subaru spectroscopy, and light-curve modeling to derive planet parameters and to eliminate stellar binaries. The resulting clean sample consists of 67 planet candidates whose radii are typically constrained to 5%, in which 23 are newly reported. The number of Jupiter-sized candidates (29 with radius r>8 R_{Earth}_) in the sample is consistent with the Doppler occurrence. The smaller candidates are more prevalent (23 with 4<r/R_{Earth}_<8, 15 with r/R_{Earth}_<4) and suggest that long-period Neptune-sized planets are at least as common as the Jupiter-sized ones, although our sample is yet to be corrected for detection completeness. If the sample is assumed to be complete, these numbers imply the occurrence rate of 0.39+/-0.07 planets with 4<r/R_{Earth}_<14 and 2<P/yr<20 per FGK dwarf. The stars hosting candidates with r>4 R_{Earth}_ have systematically higher [Fe/H] than do the Kepler field stars, providing evidence that giant planet-metallicity correlation extends to P>2 yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/712/925
- Title:
- Transition circumstellar disks in Ophiuchus
- Short Name:
- J/ApJ/712/925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained millimeter-wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 26 Spitzer-selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d~125pc) and have spectral energy distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from <0.6 to 40M_JUP_ and accretion rates ranging from <10^-11^ to 10^-7^M_{sun}_/yr, but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes). Eight of our targets have stellar companions: six of them are binaries and the other two are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that nine of our 26 targets have low disk mass (<2.5M_JUP_) and negligible accretion (<10^-11^M_{sun}_/yr), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these nine non-accreting objects have fractional disk luminosities <10^-3^ and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining four accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A36
- Title:
- Transition disks around evolved stars
- Short Name:
- J/A+A/658/A36
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Post-AGB binaries are surrounded by massive disks of gas and dust that are similar to protoplanetary disks surrounding young stars. We assembled a catalog of all known Galactic post-AGB binaries with disks. We explore correlations between the different observables with the aim to learn more about potential disk-binary interactions. We compiled spectral energy distributions of 85 Galactic post-AGB binary systems. We built-up a color-color diagram to differentiate between the different disk morphologies traced by the characteristics of the infrared excess. We categorised different disk types and looked for correlations with other observational characteristics of these systems. 8 to 12% of our targets are surrounded by transition disks, i.e. disks having no or low near-infrared excesses. We find a strong link between these transition disks and the depletion of refractory elements seen on the surface of the post-AGB star. We interpret this correlation as evidence for the presence of a mechanism that stimulates the dust and gas separation within the disk and which also produces the transition disk structure. We propose that such a mechanism can be a giant planet carving a hole in the disk which traps the dust in the outer disk parts. We propose two disk evolutionary scenarios, depending on the presence of such a giant planet in the disk. We advocate that giant planets can successfully explain the correlation between the transition disks and the depletion of refractory materials observed in post-AGB binaries. If the planetary scenario is confirmed, disks around post-AGB binaries could be a unique laboratory to test planet-disk interactions and their influence on the late evolution of binary stars. Whether the planets are first or second generation also remains to be studied. We argue that these disks are the perfect place to study planet formation scenarios in an unprecedented parameter space.
- ID:
- ivo://CDS.VizieR/J/AJ/156/218
- Title:
- Transit light curves of TRAPPIST-1 planets
- Short Name:
- J/AJ/156/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The TRAPPIST-1 planetary system provides an exceptional opportunity for the atmospheric characterization of temperate terrestrial exoplanets with the upcoming James Webb Space Telescope (JWST). Assessing the potential impact of stellar contamination on the planets' transit transmission spectra is an essential precursor to this characterization. Planetary transits themselves can be used to scan the stellar photosphere and to constrain its heterogeneity through transit depth variations in time and wavelength. In this context, we present our analysis of 169 transits observed in the optical from space with K2 and from the ground with the SPECULOOS and Liverpool telescopes. Combining our measured transit depths with literature results gathered in the mid-/near-IR with Spitzer/IRAC and HST/WFC3, we construct the broadband transmission spectra of the TRAPPIST-1 planets over the 0.8-4.5 {mu}m spectral range. While planet b, d, and f spectra show some structures at the 200-300 ppm level, the four others are globally flat. Even if we cannot discard their instrumental origins, two scenarios seem to be favored by the data: a stellar photosphere dominated by a few high-latitude giant (cold) spots, or, alternatively, by a few small and hot (3500-4000 K) faculae. In both cases, the stellar contamination of the transit transmission spectra is expected to be less dramatic than predicted in recent papers. Nevertheless, based on our results, stellar contamination can still be of comparable or greater order than planetary atmospheric signals at certain wavelengths. Understanding and correcting the effects of stellar heterogeneity therefore appears essential for preparing for the exploration of TRAPPIST-1 with JWST.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/46
- Title:
- Transit metric for Q1-Q17 Kepler candidates
- Short Name:
- J/ApJ/812/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a new metric that uses machine learning to determine if a periodic signal found in a photometric time series appears to be shaped like the signature of a transiting exoplanet. This metric uses dimensionality reduction and k-nearest neighbors to determine whether a given signal is sufficiently similar to known transits in the same data set. This metric is being used by the Kepler Robovetter to determine which signals should be part of the Q1-Q17 DR24 catalog of planetary candidates. The Kepler Mission reports roughly 20000 potential transiting signals with each run of its pipeline, yet only a few thousand appear to be sufficiently transit shaped to be part of the catalog. The other signals tend to be variable stars and instrumental noise. With this metric, we are able to remove more than 90% of the non-transiting signals while retaining more than 99% of the known planet candidates. When tested with injected transits, less than 1% are lost. This metric will enable the Kepler mission and future missions looking for transiting planets to rapidly and consistently find the best planetary candidates for follow-up and cataloging.
- ID:
- ivo://CDS.VizieR/J/AJ/154/64
- Title:
- Transit times of Kepler-448b and Kepler-693b
- Short Name:
- J/AJ/154/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I report the discovery of non-transiting close companions to two transiting warm Jupiters (WJs), Kepler-448/KOI-12b (orbital period P=17.9days, radius R_p_=1.23_-0.05_^+0.06^R_Jup_) and Kepler-693/KOI-824b (P=15.4days, R_p_=0.91+/-0.05R_Jup_), via dynamical modeling of their transit timing and duration variations (TTVs and TDVs). The companions have masses of 22_-5_^+7^M_Jup_ (Kepler-448c) and 150_-40_^+60^M_Jup_ (Kepler-693c), and both are on eccentric orbits (e=0.65_-0.09_^+0.13^ for Kepler-448c and e=0.47_-0.06_^+0.11^ for Kepler-693c) with periastron distances of 1.5au. Moderate eccentricities are detected for the inner orbits as well (e=0.34_-0.07_^+0.08^ for Kepler-448b and e=0.2_-0.1_^+0.2^ for Kepler-693b). In the Kepler-693 system, a large mutual inclination between the inner and outer orbits (53_-9_^+7^deg or 134_-10_^+11^deg) is also revealed by the TDVs. This is likely to induce a secular oscillation in the eccentricity of the inner WJ that brings its periastron close enough to the host star for tidal star-planet interactions to be significant. In the Kepler-448 system, the mutual inclination is weakly constrained, and such an eccentricity oscillation is possible for a fraction of the solutions. Thus these WJs may be undergoing tidal migration to become hot Jupiters (HJs), although the migration via this process from beyond the snow line is disfavored by the close-in and massive nature of the companions. This may indicate that WJs can be formed in situ and could even evolve into HJs via high-eccentricity migration inside the snow line.