- ID:
- ivo://CDS.VizieR/J/ApJ/791/10
- Title:
- Radius distribution of planets around cool stars
- Short Name:
- J/ApJ/791/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We calculate an empirical, non-parametric estimate of the shape of the period-marginalized radius distribution of planets with periods less than 150 days using the small yet well-characterized sample of cool (T_eff_< 4000 K) dwarf stars in the Kepler catalog. In particular, we present and validate a new procedure, based on weighted kernel density estimation, to reconstruct the shape of the planet radius function down to radii smaller than the completeness limit of the survey at the longest periods. Under the assumption that the period distribution of planets does not change dramatically with planet radius, we show that the occurrence of planets around these stars continues to increase to below 1 R_{sun}_, and that there is no strong evidence for a turnover in the planet radius function. In fact, we demonstrate using many iterations of simulated data that a spurious turnover may be inferred from data even when the true distribution continues to rise toward smaller radii. Finally, the sharp rise in the radius distribution below ~3 R_{sun}_ implies that a large number of planets await discovery around cool dwarfs as the sensitivities of ground-based transit surveys increase.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/152/18
- Title:
- Robo-AO Kepler planetary candidate survey. II.
- Short Name:
- J/AJ/152/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high angular resolution, visible light, laser adaptive optics (AOs) imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to {Delta}m{approx}6 that contribute to Kepler's measured light curves. We found 203 companions within ~4'' of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby star probability for this sample of Kepler planet candidate host stars to be 10.6%+/-1.1% at angular separations up to 2.5'', significantly higher than the 7.4%+/-1.0% probability discovered in our initial sample of 715 stars; we find the probability increases to 17.6%+/-1.5% out to a separation of 4.0''. The median position of Kepler Objects of Interest (KOIs) observed in this survey are 1.1{deg} closer to the galactic plane, which may account for some of the nearby star probability enhancement. We additionally detail 50 Keck AO images of Robo-AO observed KOIs in order to confirm 37 companions detected at a <5{sigma} significance level and to obtain additional infrared photometry on higher significance detected companions.
- ID:
- ivo://CDS.VizieR/J/ApJ/801/3
- Title:
- Rotation periods for Q3-Q14 KOIs
- Short Name:
- J/ApJ/801/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observed amplitude of the rotational photometric modulation of a star with spots should depend on the inclination of its rotational axis relative to our line of sight. Therefore, the distribution of observed rotational amplitudes of a large sample of stars depends on the distribution of their projected axes of rotation. Thus, comparison of the stellar rotational amplitudes of the Kepler objects of interest (KOIs) with those of Kepler single stars can provide a measure to indirectly infer the properties of the spin-orbit obliquity of Kepler planets. We apply this technique to the large samples of 993 KOIs and 33614 single Kepler stars in temperature range of 3500-6500K. We find with high significance that the amplitudes of cool KOIs are larger, on the order of 10%, than those of the single stars. In contrast, the amplitudes of hot KOIs are systematically lower. After correcting for an observational bias, we estimate that the amplitudes of the hot KOIs are smaller than the single stars by about the same factor of 10%. The border line between the relatively larger and smaller amplitudes, relative to the amplitudes of the single stars, occurs at about 6000K. Our results suggest that the cool stars have their planets aligned with their stellar rotation, while the planets around hot stars have large obliquities, consistent with the findings of Winn et al. (2010ApJ...718L.145W) and Albrecht et al. (2012, J/ApJ/757/18). We show that the low obliquity of the planets around cool stars extends up to at least 50 days, a feature that is not expected in the framework of a model that assumes the low obliquity is due to planet-star tidal realignment.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/1503
- Title:
- RV curves of WASP-16, 25 and 31
- Short Name:
- J/MNRAS/423/1503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new measurements of the Rossiter-McLaughlin (RM) effect for three Wide Angle Search for transiting Planets (WASP) planetary systems, WASP-16, WASP-25 and WASP-31, from a combined analysis of their complete sets of photometric and spectroscopic data.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A2
- Title:
- Saturnian satellites Cassini ISS astrometry
- Short Name:
- J/A+A/610/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Caviar is a software package designed for the astrometric measurement of natural satellite positions in images taken using the Imaging Science Subsystem (ISS) of the Cassini spacecraft. We provide new astrometric positions for selected major satellites of Saturn, 2013-2016.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A76
- Title:
- Saturnian satellites in the Gaia ref. frame
- Short Name:
- J/A+A/645/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a remeasurement of old photographic plates, providing important raw data for dynamical studies of the Saturnian satellite system. The unprecedentedly accurate realization of the Gaia reference frame allows us to make a precise calibration of digitized astronegatives of the Saturnian satellite images. We reprocessed 357 astronegatives taken with the 26-inch refractor and the normal astrograph of the Pulkovo Observatory between 1972 and 2007 to obtain the positions of the main Saturnian moons in the second Gaia data release (Gaia DR2) system. Photographic plates were digitized with the Pulkovo Mobile Digitizing Device (MDD) scanner. The New Astrometric Reduction of Old Observations (NAROO) digitizer at the Paris Observatory was used to calibrate the scanned images. Satellite image centering and astrometric reduction were performed. In total, 6487 positions (equatorial coordinates) have been determined with an accuracy of 50mas. This is confirmed by a comparison of our data with modern ephemerides. The verification of the results was performed using data from past close approaches by Saturnian satellites to Gaia reference stars, showing the adequacy of the current residual analysis. A joint review of the Pulkovo and the United States Naval Observatory (USNO) intersatellite positions allows us to conclude about the existence of faint systematic effects in the satellite theories of motions at the 10mas level.
- ID:
- ivo://CDS.VizieR/III/185
- Title:
- Search for Jupiter-Mass Companions
- Short Name:
- III/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From 1980 to 1992, the radial velocities of 17 bright solar-type dwarf and 4 subgiant stars were monitored at the Canada-France-Hawaii 3.6-m telescope (CFHT).
- ID:
- ivo://CDS.VizieR/VI/151
- Title:
- Search for radio emission from giant exoplanets
- Short Name:
- VI/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The intensity of Jupiter's auroral radio emission quickly gave rise to the question whether a comparable coherent emission from the magnetosphere of an exoplanet could be detectable. An exoplanetary radio emission would have to be at least 1000 times more intense than Jupiter's emission to be detectable with current radio telescopes. Theoretical models suggest that, at least in certain cases, the radio emission of giant exoplanets may indeed reach the required intensity. At the same time, in order to generate such an emission, an exoplanet would have to have a sufficiently strong intrinsic planetary magnetic field. Extrasolar planets are indeed expected to have a planetary magnetic field, but to date, their magnetic field has never been detected. We will show that the most promising technique to observe exoplanetary magnetic fields is indeed to search for the planetary auroral radio emission. The detection of such an emission would thus constitute the first unambiguous detection of an exoplanetary magnetic field. We will review recent theoretical studies and discuss their results for the two main parameters, namely the maximum emission frequency and the intensity of the radio emission. The predicted values should allow the detection using modern low-frequency radio telescopes. We will present an ongoing observation program with the Low Frequency Array (LOFAR), which has the potential to detect exoplanetary radio emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/582/1123
- Title:
- Search for transiting extrasolar planets
- Short Name:
- J/ApJ/582/1123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planet transit searches promise to be the next breakthrough for extrasolar planet detection and will bring the characterization of short-period planets into a new era. Every transiting planet discovered will have a measured radius, which will provide constraints on planet composition, evolution, and migration history. Together with radial velocity measurements, the absolute mass of every transiting planet will be determined. In this paper we discuss the design considerations of the Extrasolar Planet Occultation Research (EXPLORE) project, a series of transiting planet searches using 4-m class telescopes to continuously monitor a single field of stars in the Galactic plane in each ~2 week observing campaign.
- ID:
- ivo://CDS.VizieR/J/AJ/152/181
- Title:
- SETI observations of exoplanets with the ATA
- Short Name:
- J/AJ/152/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report radio SETI observations on a large number of known exoplanets and other nearby star systems using the Allen Telescope Array (ATA). Observations were made over about 19000hr from 2009 May to 2015 December. This search focused on narrowband radio signals from a set totaling 9293 stars, including 2015 exoplanet stars and Kepler objects of interest and an additional 65 whose planets may be close to their habitable zones. The ATA observations were made using multiple synthesized beams and an anticoincidence filter to help identify terrestrial radio interference. Stars were observed over frequencies from 1 to 9GHz in multiple bands that avoid strong terrestrial communication frequencies. Data were processed in near-real time for narrowband (0.7-100Hz) continuous and pulsed signals with transmitter/receiver relative accelerations from -0.3 to 0.3m/s^2^. A total of 1.9x10^8^ unique signals requiring immediate follow-up were detected in observations covering more than 8x10^6^ star-MHz. We detected no persistent signals from extraterrestrial technology exceeding our frequency-dependent sensitivity threshold of 180-310x10^-26^W/m^2^.
