- ID:
- ivo://CDS.VizieR/J/AJ/158/87
- Title:
- 86 cool dwarfs observed during K2 Campaigns 1-17
- Short Name:
- J/AJ/158/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present revised stellar properties for 172 K2 target stars that were identified as possible hosts of transiting planets during Campaigns 1-17. Using medium-resolution near-infrared spectra acquired with the NASA Infrared Telescope Facility/SpeX and Palomar/TripleSpec, we found that 86 of our targets were bona fide cool dwarfs, 74 were hotter dwarfs, and 12 were giants. Combining our spectroscopic metallicities with Gaia parallaxes and archival photometry, we derived photometric stellar parameters and compared them to our spectroscopic estimates. Although our spectroscopic and photometric radius and temperature estimates are consistent, our photometric mass estimates are systematically {Delta}M_*_=0.11 M_{sun}_ (34%) higher than our spectroscopic mass estimates for the least massive stars (M_*,phot_<0.4 M_{sun}_). Adopting the photometric parameters and comparing our results to parameters reported in the Ecliptic Plane Input Catalog, our revised stellar radii are {Delta}R_*_=0.15 R_{sun}_ (40%) larger, and our revised stellar effective temperatures are roughly {Delta}T_eff_=65 K cooler. Correctly determining the properties of K2 target stars is essential for characterizing any associated planet candidates, estimating the planet search sensitivity, and calculating planet occurrence rates. Even though Gaia parallaxes have increased the power of photometric surveys, spectroscopic characterization remains essential for determining stellar metallicities and investigating correlations between stellar metallicity and planetary properties.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/619/A97
- Title:
- CoRoT transit catalogue
- Short Name:
- J/A+A/619/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CoRoT space mission observed 163665 stars over 26 stellar fields in the faint star channel. The exoplanet teams detected a total of 4123 transit-like features in the 177454 light curves. We present the complete re-analysis of all these detections carried out with the same softwares so that to ensure their homogeneous analysis. Although the vetting process involves some human evaluation, it also involves a simple binary flag system over basic tests: detection significance, presence of a secondary, difference between odd and even depths, colour dependence, V-shape transit, and duration of the transit. We also gathered the information from the large accompanying ground-based programme carried out on the planet candidates and checked how useful the flag system could have been at the vetting stage of the candidates. From the initial list of transit-like features, we identified and separated 824 false alarms of various kind, 2269 eclipsing binaries among which 616 are contact binaries and 1653 are detached ones, 37 planets and brown dwarfs, and 557 planet candidates. We provide the catalogue of all these transit-like features, including false alarms. For the planet candidates, the catalogue gives not only their transit parameters but also the products of their light curve modelling: reduced radius, reduced semi-major axis, and impact parameter, together with a summary of the outcome of follow-up observations when carried out and their current status. For the detached eclipsing binaries, the catalogue provides, in addition to their transit parameters, a simple visual classification. Among the planet candidates whose nature remains unresolved, we estimate that eight (within an error of three) planets are still to be identified. After correcting for geometric and sensitivity biases, we derived planet and brown dwarf occurrences and confirm disagreements with Kepler estimates, as previously reported by other authors from the analysis of the first runs: small-size planets with orbital period less than ten days are underabundant by a factor of three in the CoRoT fields whereas giant planets are overabundant by a factor of two. These preliminary results would however deserve further investigations using the recently released CoRoT light curves that are corrected of the various instrumental effects and a homogeneous analysis of the stellar populations observed by the two missions.
- ID:
- ivo://CDS.VizieR/J/AJ/159/41
- Title:
- Data for ~550 exoplanets using a neural network
- Short Name:
- J/AJ/159/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While thousands of exoplanets have been confirmed, the known properties about individual discoveries remain sparse and depend on detection technique. To utilize more than a small section of the exoplanet data set, tools need to be developed to estimate missing values based on the known measurements. Here, we demonstrate the use of a neural network that models the density of planets in a space of six properties that is then used to impute a probability distribution for missing values. Our results focus on planetary mass, which neither the radial velocity nor transit techniques for planet identification can provide alone. The neural network can impute mass across the four orders of magnitude in the exoplanet archive, and return a distribution of masses for each planet that can inform us about trends in the underlying data set. The average error on this mass estimate from a radial velocity detection is a factor of 1.5 of the observed value, and 2.7 for a transit observation. The mass of Proxima Centauri b found by this method is 1.6_-0.36_^+0.46^M{Earth}, where the upper and lower bounds are derived from the root mean square deviation from the log mass probability distribution. The network can similarly impute the other potentially missing properties, and we use this to predict planet radius for radial velocity measurements, with an average error of a factor 1.4 of the observed value. The ability of neural networks to search for patterns in multidimensional data means that such techniques have the potential to greatly expand the use of the exoplanet catalog.
- ID:
- ivo://CDS.VizieR/J/AJ/157/124
- Title:
- DAVE. I. Benchmarking K2 vetting tools
- Short Name:
- J/AJ/157/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have adapted the algorithmic tools developed during the Kepler mission to vet the quality of transit-like signals for use on the K2 mission data. Using the four sets of publicly available light curves at MAST, we produced a uniformly vetted catalog of 772 transiting planet candidates from K2 as listed at the NASA Exoplanet Archive in the K2 Table of Candidates. Our analysis marks 676 of these as planet candidates and 96 as false positives. All confirmed planets pass our vetting tests. Sixty of our false positives are new identifications, effectively doubling the overall number of astrophysical signals mimicking planetary transits in K2 data. Most of the targets listed as false positives in our catalog show either prominent secondary eclipses, transit depths suggesting a stellar companion instead of a planet, or significant photocenter shifts during transit. We packaged our tools into the open-source, automated vetting pipeline Discovery and Vetting of Exoplanets (DAVE), designed to streamline follow-up efforts by reducing the time and resources wasted observing targets that are likely false positives. DAVE will also be a valuable tool for analyzing planet candidates from NASA's TESS mission, where several guest-investigator programs will provide independent light-curve sets - and likely many more from the community. We are currently testing DAVE on recently released TESS planet candidates and will present our results in a follow-up paper.
- ID:
- ivo://CDS.VizieR/J/AJ/160/84
- Title:
- Depth-of-search & completness for 213 exoplanets
- Short Name:
- J/AJ/160/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Identifying which systems are more likely to host an imageable planet can play an important role in the construction of an optimized target list for future direct imaging missions, such as the planned Coronagraph Instrument (CGI) technology demonstration for the Nancy Grace Roman Space Telescope. For single-planet systems, the presence of an already detected exoplanet can severely restrict the target's stable region and should therefore be considered when searching for unknown companions. To do so, we first analyze the performance and robustness of several two-planet stability criteria by comparing them with long-term numerical simulations. We then derive the necessary formulation for the computation of (a, R) analytic stability maps, which can be used in conjunction with depth-of-search grids in order to define the stable-imageable region of a system. The dynamically stable completeness (i.e., the expected number of imageable and stable planets) can then be calculated via convolution with the selected occurrence grid, obtaining a metric that can be directly compared for imaging prioritization. Applying this procedure to all the currently known single-planet systems within a distance of 50pc, we construct a ranked target list based on the CGI's predicted performance and SAG13 occurrence rates. Finally, we evaluate the importance of considering the radial velocity data from past Doppler surveys in order to rule out entire regions of our parameter space where, if a planet existed, it would have certainly been detected by previous RV observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/1763
- Title:
- Detectability of radio emission from exoplanets
- Short Name:
- J/MNRAS/478/1763
- Date:
- 19 Jan 2022 00:23:37
- Publisher:
- CDS
- Description:
- Like the magnetized planets in our Solar system, magnetized exoplanets should emit strongly at radio wavelengths. Radio emission directly traces the planetary magnetic fields and radio detections can place constraints on the physical parameters of these features. Large comparative studies of predicted radio emission characteristics for the known population of exoplanets help to identify what physical parameters could be the key for producing bright, observable radio emission. Since the last comparative study, many thousands of exoplanets have been discovered. We report new estimates for the radio flux densities and maximum emission frequencies for the current population of known exoplanets orbiting pre-main-sequence and main-sequence stars with spectral types F-M. The set of exoplanets predicted to produce observable radio emission are Hot Jupiters orbiting young stars. The youth of these systems predicts strong stellar magnetic fields and/or dense winds, which are the key for producing bright, observable radio emission. We use a new all-sky circular polarization Murchison Widefield Array survey to place sensitive limits on 200MHz emission from exoplanets, with 3{sigma} values ranging from 4.0 to 45.0mJy. Using a targeted Giant Metrewave Radio Telescope observing campaign, we also report a 3{sigma} upper limit of 4.5mJy on the radio emission from V830 Tau b, the first Hot Jupiter to be discovered orbiting a pre-main-sequence star. Our limit is the first to be reported for the low-frequency radio emission from this source.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A7
- Title:
- Determining true mass of RV exoplanets with Gaia
- Short Name:
- J/A+A/645/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplan- ets lack a measurement of their true mass, in particular those detected as a result of radial-velocity (RV) variations of their host star. For those examples, only the minimum mass, or msini, is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane of the sky. The mass that is given in databases is generally that of an assumed edge-on system (~90{deg}), but many other inclinations are possible, even extreme values closer to 0{deg} (face-on). In such a case, the mass of the published object could be strongly underestimated by up to two orders of magnitude. In the present study, we use GASTON, a recently developed tool taking advantage of the voluminous Gaia astrometric database to constrain the inclination and true mass of several hundreds of published exoplanet candidates. We find 9 exoplanet candidates in the stellar or brown dwarf (BD) domain, among which 6 were never characterized. We show that 30 Ari B b, HD 141937 b, HD 148427 b, HD 6718 b, HIP 65891 b, and HD 16760 b have masses larger than 13.5 M_J_ at 3{sigma}. We also confirm the planetary nature of 27 exoplanets, including HD 10180 c, d and g. Studying the orbital periods, eccentricities, and host-star metallicities in the BD domain, we found distributions with respect to true masses consistent with other publications. The distribution of orbital periods shows of a void of BD detections below ~100d, while eccentricity and metallicity distributions agree with a transition between BDs similar to planets and BDs similar to stars in the range 40-50M_J_.
- ID:
- ivo://CDS.VizieR/J/AJ/158/141
- Title:
- Differential photometry & RVs of HAT-P-69 & HAT-P-70
- Short Name:
- J/AJ/158/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the Transiting Exoplanet Survey Satellite. HAT-P-69 b has a mass of 3.58_-0.58_^+0.58^ M_Jup_ and a radius of 1.676_-0.033_^+0.051^ R_Jup_ and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of 1.87_-0.10_^+0.15^ R_Jup_ and a mass constraint of <6.78 (3{sigma}) M_Jup_ and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47126 main-sequence stars brighter than T_mag_=10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41+/-0.10% within this sample, consistent with the rate measured by Kepler for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71+/-0.31% for G stars, 0.43+/-0.15% for F stars, and 0.26+/-0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A73
- Title:
- Discovery of the directly imaged planet YSES 2b
- Short Name:
- J/A+A/648/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the origin and formation pathway of wide-orbit gas giant planets, it is necessary to expand the limited sample of these objects. The mass of exoplanets derived with spectrophotometry, however, varies strongly as a function of the age of the system and the mass of the primary star. By selecting stars with similar ages and masses, the Young Suns Exoplanet Survey (YSES) aims to detect and characterize planetary-mass companions to solar-type host stars in the Scorpius-Centaurus association. Our survey is carried out with VLT/SPHERE with short exposure sequences on the order of 5-min per star per filter. The subtraction of the stellar point spread function (PSF) is based on reference star differential imaging (RDI) using the other targets (with similar colors and magnitudes) in the survey in combination with principal component analysis. Two astrometric epochs that are separated by more than one year are used to confirm co-moving companions by proper motion analysis. We report the discovery of YSES 2b, a co-moving, planetary-mass companion to the K1 star YSES 2 (TYC 8984-2245-1, 2MASS J11275535-6626046). The primary has a Gaia EDR3 distance of 110pc, and we derive a revised mass of 1.1M_{sun}_ and an age of approximately 14Myr. We detect the companion in two observing epochs southwest of the star at a position angle of 205{deg} and with a separation of ~1.05", which translates to a minimum physical separation of 115au at the distance of the system. Photometric measurements in the H and Ks bands are indicative of a late L spectral type, similar to the innermost planets around HR 8799. We derive a photometric planet mass of 6.3^+1.6^_-0.9_M_{Jup}_ using AMES-COND and AMES-dusty evolutionary models; this mass corresponds to a mass ratio of q=(0.5+/-0.1)% with the primary. This is the lowest mass ratio of a direct imaging planet around a solar-type star to date. We discuss potential formation mechanisms and find that the current position of the planet is compatible with formation by disk gravitational instability, but its mass is lower than expected from numerical simulations. Formation via core accretion must have occurred closer to the star, yet we do not find evidence that supports the required outward migration, such as via scattering off another undiscovered companion in the system. We can exclude additional companions with masses greater than 13M_{Jup}_ in the full field of view of the detector (0.15"<{rho}<5.50"), at 0.5" we can rule out further objects that are more massive than 6M_{Jup}_, and for projected separations {rho}>2arcsec we are sensitive to planets with masses as low as 2M_{Jup}_. YSES 2b is an ideal target for follow-up observations to further the understanding of the physical and chemical formation mechanisms of wide-orbit Jovian planets. The YSES strategy of short snapshot observations (<=5min) and PSF subtraction based on a large reference library proves to be extremely efficient and should be considered for future direct imaging surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/155/165
- Title:
- Dissipation in exoplanet hosts from tidal spin-up
- Short Name:
- J/AJ/155/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stars with hot Jupiters (HJs) tend to rotate faster than other stars of the same age and mass. This trend has been attributed to tidal interactions between the star and planet. A constraint on the dissipation parameter Q_*_' follows from the assumption that tides have managed to spin up the star to the observed rate within the age of the system. This technique was applied previously to HATS-18 and WASP-19. Here, we analyze the sample of all 188 known HJs with an orbital period <3.5 days and a "cool" host star (T_eff_<6100 K). We find evidence that the tidal dissipation parameter (Q_*_') increases sharply with forcing frequency, from 10^5^ at 0.5 day^-1^ to 10^7^ at 2 day^-1^. This helps to resolve a number of apparent discrepancies between studies of tidal dissipation in binary stars, HJs, and warm Jupiters. It may also allow for a HJ to damp the obliquity of its host star prior to being destroyed by tidal decay.
