- ID:
- ivo://CDS.VizieR/J/A+A/390/267
- Title:
- The CORALIE survey for extrasolar planets VIII
- Short Name:
- J/A+A/390/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Doppler CORALIE measurements of the solar-type stars HD 141937, HD 162020, HD 168443 and HD 202206 show Keplerian radial-velocity variations revealing the presence of 4 new companions with minimum masses close to the planet/brown-dwarf transition, namely with m_2_sini=9.7, 14.4, 16.9, and 17.5M_Jup_, respectively. The orbits present fairly large eccentricities (0.22<=e<=0.43). Except for HD 162020 , the parent stars are metal rich compared to the Sun, as are most of the detected extra-solar planet hosts. Considerations of tidal dissipation in the short-period HD 162020 system points towards a brown-dwarf nature for the low-mass companion. HD 168443 is a multiple system with two low-mass companions being either brown dwarfs or formed simultaneously in the protoplanetary disks as superplanets. For HD 202206, the radial velocities show an additional drift revealing a further outer companion, the nature of which is still unknown. Finally, the stellar-host and orbital properties of massive planets are examined in comparison to lighter exoplanets. Observed trends include the need of metal-rich stars to form massive exoplanets and the lack of short periods for massive planets. If confirmed with improved statistics, these features may provide constraints for the migration scenario.
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- ID:
- ivo://CDS.VizieR/J/A+A/415/391
- Title:
- The CORALIE survey for extrasolar planets. XII
- Short Name:
- J/A+A/415/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper summarizes the information gathered for 16 exoplanet candidates discovered with the CORALIE echelle spectrograph mounted on the Euler Swiss telescope at La Silla Observatory. Here we give individual velocity measurements for the 13 stars harbouring a single planet companion. The data for the multi-planet systems will be published later.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/24
- Title:
- The first three quarters of Kepler mission
- Short Name:
- J/ApJS/199/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for potential transit signals in the first three quarters of photometry data acquired by the Kepler mission. The targets of the search include 151722 stars which were observed over the full interval and an additional 19132 stars which were observed for only one or two quarters. From this set of targets we find a total of 5392 detections which meet the Kepler detection criteria: those criteria are periodicity of signal, an acceptable signal-to-noise ratio, and a composition test which rejects spurious detections which contain non-physical combinations of events. The detected signals are dominated by events with relatively low signal-to-noise ratio and by events with relatively short periods. The distribution of estimated transit depths appears to peak in the range between 40 and 100 parts per million, with a few detections down to fewer than 10 parts per million. The detections exhibit signal-to-noise ratios from 7.1{sigma}, which is the lower cutoff for detections, to over 10000{sigma}, and periods ranging from 0.5 days, which is the lower cutoff used in the procedure, to 109 days, which is the upper limit of achievable periods given the length of the data set and the criteria used for detections. The detected signals are compared to a set of known transit events in the Kepler field of view which were derived by a different method using a longer data interval; the comparison shows that the current search correctly identified 88.1% of the known events.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/92
- Title:
- The hot Jupiter Kepler-13Ab planet's occultation
- Short Name:
- J/ApJ/788/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-13Ab (= KOI-13.01) is a unique transiting hot Jupiter. It is one of very few known short-period planets orbiting a hot A-type star, making it one of the hottest planets currently known. The availability of Kepler data allows us to measure the planet's occultation (secondary eclipse) and phase curve in the optical, which we combine with occultations observed by warm Spitzer at 4.5 {mu}m and 3.6 {mu}m and a ground-based occultation observation in the K_s_ band (2.1 {mu}m). We derive a day-side hemisphere temperature of 2750+/-160 K as the effective temperature of a black body showing the same occultation depths. Comparing the occultation depths with one-dimensional planetary atmosphere models suggests the presence of an atmospheric temperature inversion. Our analysis shows evidence for a relatively high geometric albedo, A_g_=0.33_-0.06_^+0.04^. While measured with a simplistic method, a high A_g_ is supported also by the fact that the one-dimensional atmosphere models underestimate the occultation depth in the optical. We use stellar spectra to determine the dilution, in the four wide bands where occultation was measured, due to the visual stellar binary companion 1.15"+/-0.05" away. The revised stellar parameters measured using these spectra are combined with other measurements, leading to revised planetary mass and radius estimates of M_p_=4.94-8.09 M_J_ and R_p_=1.406+/-0.038 R_J_. Finally, we measure a Kepler midoccultation time that is 34.0+/-6.9 s earlier than expected based on the midtransit time and the delay due to light-travel time and discuss possible scenarios.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A9
- Title:
- The International Deep Planet Survey. I.
- Short Name:
- J/A+A/544/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Breakthrough direct detections of planetary companions orbiting A-type stars confirm the existence of massive planets at relatively large separations, but dedicated surveys are required to estimate the frequency of similar planetary systems. To measure the first estimation of the giant exoplanetary systems frequency at large orbital separation around A-stars, we have conducted a deep-imaging survey of young (8-400Myr), nearby (19-84pc) A- and F-stars to search for substellar companions in the ~10-300AU range. The sample of 42 stars combines all A-stars observed in previous AO planet search surveys reported in the literature with new AO observations from VLT/NaCo and Gemini/NIRI. It represents an initial subset of the International Deep Planet Survey (IDPS) sample of stars covering M- to B-stars. The data were obtained with diffraction-limited observations in H- and Ks-band combined with angular differential imaging to suppress the speckle noise of the central stars, resulting in typical 5-sigma detection limits in magnitude difference of 12mag at 1", 14mag at 2" and 16mag at 5" which is sufficient to detect massive planets. A detailed statistical analysis of the survey results is performed using Monte Carlo simulations. Considering the planet detections, we estimate the fraction of A-stars having at least one massive planet (3-14M_Jup_) in the range 5-320AU to be inside 5.9-18.8% at 68% confidence, assuming a flat distribution for the mass of the planets. By comparison, the brown dwarf (15-75M_Jup_) frequency for the sample is 2.0-8.9% at 68% confidence in the range 5-320AU. Assuming power law distributions for the mass and semimajor axis of the planet population, the AO data are consistent with a declining number of massive planets with increasing orbital radius which is distinct from the rising slope inferred from radial velocity (RV) surveys around evolved A-stars and suggests that the peak of the massive planet population around A-stars may occur at separations between the ranges probed by existing RV and AO observations. Finally, we report the discovery of three new close M-star companions to HIP 104365 and HIP 42334.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/15
- Title:
- The Kepler-20 planetary system
- Short Name:
- J/ApJ/749/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASS J19104752+4220194. From high-resolution spectroscopy of the star, we find a stellar effective temperature T_eff_= 5455+/-100 K, a metallicity of [Fe/H] = 0.01+/-0.04, and a surface gravity of log g = 4.4+/-0.1. We combine these estimates with an estimate of the stellar density derived from the transit light curves to deduce a stellar mass of M_*_ = 0.912+/-0.034 M_{sun}_and a stellar radius of R_*_ = 0.944^+0.060^_-0.095_R_{sun}_. For three of the transit signals, we demonstrate that our results strongly disfavor the possibility that these result from astrophysical false positives. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70 days and 1.91^+0.12^_-0.21_R_{earth}_ for Kepler-20b, 10.85 days and 3.07^+0.20^_-0.31_R_{earth}_ for Kepler-20c, and 77.61 days and 2.75^+0.17^_-0.30_R_{earth}_ for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7+/-2.2 M_{earth}_ and 16.1 +/-3.5 M_{earth}_, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 M_{earth}_(2{sigma}).
- ID:
- ivo://CDS.VizieR/J/AJ/153/147
- Title:
- The orbits of Jupiter's irregular satellites
- Short Name:
- J/AJ/153/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the improved ephemerides for the irregular Jovian satellites. We used a combination of numerically integrated equations of motion and a weighted least-squares algorithm to fit the astrometric measurements. The orbital fits for 59 satellites are summarized in terms of state vectors, post-fit residuals, and mean orbital elements. The current data set appears to be sensitive to the mass of Himalia, which is constrained to the range of GM=0.13-0.28 km^3^/s^2^. Here, GM is the product of the Newtonian constant of gravitation, G and the body's mass, M. Our analysis of the orbital uncertainties indicates that 11 out of 59 satellites are lost owing to short data arcs. The lost satellites hold provisional International Astronomical Union (IAU) designations and will likely need to be rediscovered.
- ID:
- ivo://CDS.VizieR/J/A+A/324/366
- Title:
- Theory of motion & ephemerides of Hyperion
- Short Name:
- J/A+A/324/366
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present a new theory of motion for Hyperion, defined like in TASS1.6 for the other Saturn's satellites (Vienne & Duriez, 1995A&A...297..588V), by the osculating saturnicentric orbital elements referred to the equatorial plane of Saturn and to the node of this plane in the mean ecliptic for J2000.0. These elements are expressed as semi-numerical trigonometric series in which the argument of each term is given as an integer combination of 7 natural fundamental arguments (Table 3). These series (Tables 4 to 7) collect all the perturbations caused by Titan on the orbital elements of Hyperion, whose amplitudes are larger than 1km in the long-period terms and than 5km in the short-period ones. Taking also account of the perturbations from other satellites and Sun (Table 8), these series have been fitted to 8136 Earth-based observations of Hyperion in the interval [1874-1985]. The resulting series allows to produce new ephemerides for Hyperion, which have been compared to those previously given by Taylor (1992A&A...265..825T): Using the same set of observations and the same way to weight them, the root mean square (o-c) residual of the present theory is 0.156-arcseconds while the ephemerides of Taylor gives 0.203-arcseconds.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/1102
- Title:
- The planet-metallicity correlation.
- Short Name:
- J/ApJ/622/1102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have recently carried out spectral synthesis modeling to determine T_eff_, log(g), vsin(i), and [Fe/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K>30m/s and orbital periods shorter than 4yr.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A94
- Title:
- The role of the host star's metallicity
- Short Name:
- J/A+A/624/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most of our current understanding of the planet formation mechanism is based on the planet metallicity correlation derived mostly from solar-type stars harbouring gas-giant planets. To achieve a more extensive grasp on the substellar formation process, we aim to analyse in terms of their metallicity a diverse sample of stars (in terms of mass and spectral type) covering the whole range of possible outcomes of the planet formation process (from planetesimals to brown dwarfs and low-mass binaries). Our methodology is based on the use of high-precision stellar parameters derived by our own group in previous works from high-resolution spectra by using the iron ionisation and equilibrium conditions. All values were derived in an homogeneous way, except for the M dwarfs where a methodology based on the use of pseudo equivalent widths of spectral features was used. Our results show that as the mass of the substellar companion increases the metallicity of the host star tends to lower values. The same trend is maintained when analysing stars with low-mass stellar companions and a tendency towards a wide range of host star's metallicity is found for systems with low-mass planets. We also confirm that more massive planets tend to orbit around more massive stars. The core-accretion formation mechanism for planet formation achieves its maximum efficiency for planets with masses in the range 0.2 and 2M_{Jup}_. Substellar objects with higher masses have higher probabilities of being formed as stars. Low-mass planets and planetesimals might be formed by core-accretion even around low-metallicity stars.