- ID:
- ivo://CDS.VizieR/J/ApJ/738/170
- Title:
- False positive Kepler planet candidates
- Short Name:
- J/ApJ/738/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a framework to conservatively estimate the probability that any particular planet-like transit signal observed by the Kepler mission is in fact a planet, prior to any ground-based follow-up efforts. We use Monte Carlo methods based on stellar population synthesis and Galactic structure models, and report false positive probabilities (FPPs) for every Kepler Object of Interest, assuming a 20% intrinsic occurrence rate of close-in planets in the radius range 0.5R_{earth}_<R_p_<20R_{earth}_. Nearly 90% of the 1235 candidates have FPP<10%, and over half have FPP<5%. This probability varies with the magnitude and Galactic latitude of the target star, and with the depth of the transit signal - deeper signals generally have higher FPPs than shallower signals. We establish that a single deep high-resolution image will be an effective follow-up tool for the shallowest (Earth-sized) transits, providing the quickest route toward probabilistically validating the smallest candidates by potentially decreasing the FPP of an Earth-sized transit around a faint star from >10% to <1%. Since Kepler has detected many more planetary signals than can be positively confirmed with ground-based follow-up efforts in the near term, these calculations will be crucial to using the ensemble of Kepler data to determine population characteristics of planetary systems. We also describe how our analysis complements the Kepler team's more detailed BLENDER false positive analysis for planet validation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/822/86
- Title:
- False positive probabilities for Q1-Q17 DR24 KOIs
- Short Name:
- J/ApJ/822/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present astrophysical false positive probability calculations for every Kepler Object of Interest (KOI) --the first large-scale demonstration of a fully automated transiting planet validation procedure. Out of 7056 KOIs, we determine that 1935 have probabilities vespa (Morton T.D. 2015ascl.soft03011M), a publicly available Python package that is able to be easily applied to any transiting exoplanet candidate.
- ID:
- ivo://CDS.VizieR/J/A+A/415/1153
- Title:
- [Fe/H] for 98 extra-solar planet-host stars
- Short Name:
- J/A+A/415/1153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar parameters and metallicities, obtained from a detailed spectroscopic analysis, for a large sample of 98 stars known to be orbited by planetary mass companions (almost all known targets), as well as for a volume-limited sample of 41 stars not known to host any planet. For most of the stars the stellar parameters are revised versions of the ones presented in our previous work. However, we also present parameters for 18 stars with planets not previously published, and a compilation of stellar parameters for the remaining 4 planet-hosts for which we could not obtain a spectrum. A comparison of our stellar parameters with values of Teff, logg, and [Fe/H] available in the literature shows a remarkable agreement. In particular, our spectroscopic logg values are now very close to trigonometric logg estimates based on Hipparcos parallaxes. The derived [Fe/H] values are then used to confirm the previously known result that planets are more prevalent around metal-rich stars.
- ID:
- ivo://CDS.VizieR/J/AJ/152/158
- Title:
- Final Kepler transiting planet search (DR25)
- Short Name:
- J/AJ/152/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of the final Kepler Data Processing Pipeline search for transiting planet signals in the full 17-quarter primary mission data set. The search includes a total of 198709 stellar targets, of which 112046 were observed in all 17 quarters and 86663 in fewer than 17 quarters. We report on 17230 targets for which at least one transit signature is identified that meets the specified detection criteria: periodicity, minimum of three observed transit events, detection statistic (i.e., signal-to-noise ratio) in excess of the search threshold, and passing grade on three statistical transit consistency tests. Light curves for which a transit signal is identified are iteratively searched for additional signatures after a limb-darkened transiting planet model is fitted to the data and transit events are removed. The search for additional planets adds 16802 transit signals for a total of 34032; this far exceeds the number of transit signatures identified in prior pipeline runs. There was a strategic emphasis on completeness over reliability for the final Kepler transit search. A comparison of the transit signals against a set of 3402 well-established, high-quality Kepler Objects of Interest yields a recovery rate of 99.8%. The high recovery rate must be weighed against a large number of false-alarm detections. We examine characteristics of the planet population implied by the transiting planet model fits with an emphasis on detections that would represent small planets orbiting in the habitable zone of their host stars.
- ID:
- ivo://CDS.VizieR/J/AJ/144/19
- Title:
- Follow-up photometry for HAT-P-34 through HAT-P-37
- Short Name:
- J/AJ/144/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four transiting extrasolar planets (HAT-P-34b-HAT-P-37b) with masses ranging from 1.05 to 3.33M_J_ and periods from 1.33 to 5.45days. These planets orbit relatively bright F and G dwarf stars (from V=10.16 to V=13.2). Of particular interest is HAT-P-34b which is moderately massive (3.33M_J_), has a high eccentricity of e=0.441+/-0.032 at a period of P=5.452654+/-0.000016days, and shows hints of an outer component. The other three planets have properties that are typical of hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A100
- Title:
- Four new SDSS eclipsing systems
- Short Name:
- J/A+A/510/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of nine cataclysmic variable stars identified by the Sloan Digital Sky Survey, aimed at measuring the orbital periods of these systems. Four of these objects show deep eclipses, from which we measure their orbital periods. The light curves of three of the eclipsing systems are also analysed using the LCURVE code, and their mass ratios and orbital inclinations determined. SDSS J075059.97+141150.1 has an orbital period of 134.1564+/-0.0008min, making it a useful object with which to investigate the evolutionary processes of cataclysmic variables. SDSS J092444.48+080150.9 has a period of 131.2432+/-0.0014min and is probably magnetic. The white dwarf ingress and egress phases are very deep and short, and there is no clear evidence that this object has an accretion disc. SDSS J115207.00+404947.8 and SDSS J152419.33+220920.1 are nearly identical twins, with periods of 97.5+/-0.4 and 93.6+/-0.5min and mass ratios of 0.14+/-0.03 and 0.17+/-0.03, respectively. Their eclipses have well-defined white dwarf and bright spot ingress and egress features, making them excellent candidates for detailed study. All four of the orbital periods presented here are shorter than the 2-3 hour period gap observed in the known population of cataclysmic variables.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A93
- Title:
- Four new transiting planets
- Short Name:
- J/A+A/572/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characterization of four new transiting extrasolar planets is presented here. KOI-188b and KOI-195b are bloated hot Saturns, with orbital periods of 3.8 and 3.2-days, and masses of 0.25 and 0.34M_Jup_, respectively. They are located in the low-mass range of known transiting, giant planets. KOI-192b has a similar mass (0.29M_Jup_) but a longer orbital period of 10.3 days. This places it in a domain where only few planets are known. KOI-830b, finally, with a mass of 1.27M_Jup_ and a period of 3.5-days, is a typical hot Jupiter. The four planets have radii of 0.98, 1.09, 1.2, and 1.08R_Jup_, respectively. We detected no significant eccentricity in any of the systems, while the accuracy of our data does not rule out possible moderate eccentricities. The four objects were first identified by the Kepler Team as promising candidates from photometry of the Kepler satellite. We establish here their planetary nature thanks to the radial velocity follow-up we secured with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. The combined analyses of the whole datasets allow us to fully characterize the four planetary systems. These new objects increase the number of well-characterized exoplanets for statistics, and provide new targets for individual follow-up studies. The pre-screening we performed with the SOPHIE spectrograph at the Observatoire de Haute-Provence as part of that study also allowed us to conclude that a fifth candidate, KOI-219.01, is not a planet but is a false positive.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/2127
- Title:
- Fundamental parameters of Kepler stars
- Short Name:
- J/MNRAS/452/2127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction of individual pulsation frequencies. We implement a new Bayesian scheme that is flexible in its input to process individual oscillation frequencies, combinations of them, and average asteroseismic parameters, and derive robust fundamental properties for these targets. Applying this scheme to grids of evolutionary models yields stellar properties with median statistical uncertainties of 1.2 per cent (radius), 1.7 per cent (density), 3.3 per cent (mass), 4.4 per cent (distance), and 14 per cent (age), making this the exoplanet host-star sample with the most precise and uniformly determined fundamental parameters to date. We assess the systematics from changes in the solar abundances and mixing-length parameter, showing that they are smaller than the statistical errors. We also determine the stellar properties with three other fitting algorithms and explore the systematics arising from using different evolution and pulsation codes, resulting in 1 per cent in density and radius, and 2 per cent and 7 per cent in mass and age, respectively. We confirm previous findings of the initial helium abundance being a source of systematics comparable to our statistical uncertainties, and discuss future prospects for constraining this parameter by combining asteroseismology and data from space missions. Finally, we compare our derived properties with those obtained using the global average asteroseismic observables along with effective temperature and metallicity, finding excellent level of agreement. Owing to selection effects, our results show that the majority of the high signal-to-noise ratio asteroseismic Kepler host stars are older than the Sun.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/4395
- Title:
- Fundamental properties of giant gas planets
- Short Name:
- J/MNRAS/445/4395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is already stated in the previous studies that the radius of the giant planets is affected by stellar irradiation. The confirmed relation between radius and incident flux depends on planetary mass intervals. In this study, we show that there is a single relation between radius and irradiated energy per gram per second (l-), for all mass intervals. There is an extra increase in radius of planets if l- is higher than 1100 times energy received by the Earth (l_{earth}_). This is likely due to dissociation of molecules. The tidal interaction as a heating mechanism is also considered and found that its maximum effect on the inflation of planets is about 15 percent. We also compute age and heavy element abundances from the properties of host stars, given in the TEPCat catalogue (Southworth). The metallicity given in the literature is as [Fe/H]. However, the most abundant element is oxygen, and there is a reverse relation between the observed abundances [Fe/H] and [O/Fe]. Therefore, we first compute [O/H] from [Fe/H] by using observed abundances, and then find heavy element abundance from [O/H]. We also develop a new method for age determination. Using the ages we find, we analyse variation of both radius and mass of the planets with respect to time, and estimate the initial mass of the planets from the relation we derive for the first time. According to our results, the highly irradiated gas giants lose 5 percent of their mass in every 1Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/9
- Title:
- GALEX observations of exoplanet host stars
- Short Name:
- J/ApJ/766/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the far-UV (FUV) and near-UV (NUV) photometry from the NASA Galaxy Evolution Explorer (GALEX), we searched for evidence of increased stellar activity due to tidal and/or magnetic star-planet interactions (SPI) in the 272 known FGK planetary hosts observed by GALEX. With the increased sensitivity of GALEX, we are able probe systems with lower activity levels and at larger distances than what has been done to date with X-ray satellites. We compared samples of stars with close-in planets (a<0.1AU) to those with far-out planets (a>0.5AU) and looked for correlations of excess activity with other system parameters. This statistical investigation found no clear correlations with a, M_p_, or M_p_/a, in contrast to some X-ray and CaII studies. However, there is tentative evidence (at a level of 1.8{sigma}) that stars with radial-velocity-(RV)-detected close-in planets are more FUV-active than stars with far-out planets, in agreement with several published X-ray and Ca II results. The case is strengthened to a level of significance to 2.3{sigma} when transit-detected close-in planets are included. This is most likely because the RV-selected sample of stars is significantly less active than the field population of comparable stars, while the transit-selected sample is similarly active. Given the factor of 2-3 scatter in fractional FUV luminosity for a given stellar effective temperature, it is necessary to conduct a time-resolved study of the planet hosts in order to better characterize their UV variability and generate a firmer statistical result.
