- ID:
- ivo://CDS.VizieR/J/MNRAS/463/1780
- Title:
- Exoplanet candidates in Praesepe (M 44)
- Short Name:
- J/MNRAS/463/1780
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we keep pushing K2 data to a high photometric precision, close to that of the Kepler main mission, using a PSF-based, neighbour-subtraction technique, which also overcome the dilution effects in crowded environments. We analyse the open cluster M 44 (NGC 2632), observed during the K2 Campaign 5, and extract light curves of stars imaged on module 14, where most of the cluster lies. We present two candidate exoplanets hosted by cluster members and five by field stars. As a by-product of our investigation, we find 1680 eclipsing binaries and variable stars, 1071 of which are new discoveries. Among them, we report the presence of a heartbeat binary star. Together with this work, we release to the community a catalogue with the variable stars and the candidate exoplanets found, as well as all our raw and detrended light curves.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/585/A5
- Title:
- Exoplanet hosts/field stars age consistency
- Short Name:
- J/A+A/585/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases could also impact transiting-planet hosts. This paper aims to evaluate how selection effects reflect on the evolutionary stage of both a limited sample of transiting-planet host stars (TPH) and a wider sample of planet-hosting stars detected through radial velocity analysis. Then, thanks to uniform derivation of stellar ages, a homogeneous comparison between exoplanet hosts and field star age distributions is developed. Stellar parameters have been computed through our custom-developed isochrone placement algorithm, according to Padova evolutionary models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of logR'_HK_ and vsini, and the evaluation of the stellar evolutionary speed in the Hertzsprung-Russel diagram in order to better constrain age. Working with TPH, the observational stellar mean density {rho}_*_ allows us to compute stellar luminosity even if the distance is not available, by combining {rho}_* with the spectroscopic logg. The median value of the TPH ages is ~5Gyr. Even if this sample is not very large, however the result is very similar to what we found for the sample of spectroscopic hosts, whose modal and median values are [3, 3.5)Gyr and ~4.8Gyr, respectively. Thus, these stellar samples suffer almost the same selection effects. An analysis of MS stars of the solar neighbourhood belonging to the same spectral types bring to an age distribution similar to the previous ones and centered around solar age value. Therefore, the age of our Sun is consistent with the age distribution of solar neighbourhood stars with spectral types from late F to early K, regardless of whether they harbour planets or not. We considered the possibility that our selected samples are older than the average disc population.
- ID:
- ivo://CDS.VizieR/J/AJ/142/176
- Title:
- Exoplanet host stars. II. Speckle interferometry
- Short Name:
- J/AJ/142/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A study of the host stars to exoplanets is important for understanding their environment. To that end, we report new speckle observations of a sample of exoplanet host primaries. The bright exoplanet host HD 8673 (= HIP 6702) is revealed to have a companion, although at this time we cannot definitively establish the companion as physical or optical. The observing lists for planet searches and for these observations have for the most part been pre-screened for known duplicity, so the detected binary fraction is lower than what would otherwise be expected. Therefore, a large number of double stars were observed contemporaneously for verification and quality control purposes, to ensure that the lack of detection of companions for exoplanet hosts was valid. In these additional observations, 10 pairs are resolved for the first time and 60 pairs are confirmed.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A156
- Title:
- Exoplanet host stars SPHERE multiplicity survey
- Short Name:
- J/A+A/649/A156
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We are studying the influence of stellar multiplicity on exoplanet systems and, in particular, systems that have been detected via radial-velocity searches. We are specifically interested in the closest companions as they would have a strong influence on the evolution of the original planet-forming disks. In this study, we present new companions that have been detected during our ongoing survey of exoplanet hosts with VLT/SPHERE (Spectro-Polarimetric High-Contrast Exoplanet Research). We are using the extreme adaptive optics imager SPHERE at the ESO/VLT to search for faint (sub)stellar companions. We utilized the classical coronagraphic imaging mode to perform a snapshot survey (3-6min integration time) of exoplanet host stars in the K_S_-band. We detected new stellar companions to the exoplanet host stars HD 1666, HIP 68468, HIP 107773, and HD 109271. With an angular separation of only 0.38arcsec (40au of projected separation), HIP 107773 is among the closest companions found for exoplanet host stars. The presence of the stellar companion explains the linear radial-velocity trend seen in the system. At such a small separation, the companion likely had a significant influence on the evolution of the planet-forming disk around the primary star. We find that the companion in the HD 1666 system may well be responsible for the high orbit eccentricity (0.63) of the detected Jupiter class planet, making this system one of only a few where such a connection can be established. A cross-match with the Gaia DR2 catalog shows, furthermore, that the near infrared faint companion around HD 109271 was detected in the optical and it is significantly brighter than in the near infrared, making it a white dwarf companion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/L46
- Title:
- Exoplanet magnetic fields
- Short Name:
- J/MNRAS/411/L46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An asymmetry between the ingress and egress times was observed in the near-UV light curve of the transit planet WASP-12b. Such asymmetry led us to suggest that the early ingress in the UV light curve of WASP-12b, compared to the optical observations, is caused by a shock around the planet, and that shocks should be a common feature in transiting systems. Here, we classify all the transiting systems known to date according to their potential for producing shocks that could cause observable light curve asymmetries.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/68
- Title:
- Exoplanet masses derived from RVs
- Short Name:
- J/ApJ/733/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet searches using radial velocity (RV) and microlensing (ML) produce samples of "projected" mass and orbital radius, respectively. We present a new method for estimating the probability density distribution (density) of the unprojected quantity from such samples. For a sample of n data values, the method involves solving n simultaneous linear equations to determine the weights of delta functions for the raw, unsmoothed density of the unprojected quantity that cause the associated cumulative distribution function (CDF) of the projected quantity to exactly reproduce the empirical CDF of the sample at the locations of the n data values. We smooth the raw density using nonparametric kernel density estimation with a normal kernel of bandwidth {sigma}. We calibrate the dependence of {sigma} on n by Monte Carlo experiments performed on samples drawn from a theoretical density, in which the integrated square error is minimized. We scale this calibration to the ranges of real RV samples using the Normal Reference Rule. The resolution and amplitude accuracy of the estimated density improve with n. For typical RV and ML samples, we expect the fractional noise at the PDF peak to be approximately 80n^-log2^. For illustrations, we apply the new method to 67 RV values given a similar treatment by Jorissen et al. (2001A&A...379..992J), and to the 308 RV values listed at exoplanets.org on 2010 October 20.
4367. Exoplanet Orbit Database
- ID:
- ivo://CDS.VizieR/J/PASP/123/412
- Title:
- Exoplanet Orbit Database
- Short Name:
- J/PASP/123/412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a database of well determined orbital parameters of exoplanets, and their host stars' properties. This database comprises spectroscopic orbital elements measured for 427 planets orbiting 363 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The Database is available in a searcheable, filterable, and sortable form on the Web at http://exoplanets.org through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanet Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the different selection biases between radial velocity and transit surveys, and that the multiplanet systems show a distinct semi-major axis distribution from apparently singleton systems.
4368. Exoplanet Orbit Database
- ID:
- ivo://nasa.heasarc/exoplanodb
- Title:
- Exoplanet Orbit Database
- Short Name:
- EXOPLANODB
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Exoplanet Orbit Database is a database of well-determined orbital parameters of exoplanets, and their host stars' properties. This database comprises spectroscopic orbital elements measured for planets orbiting their host stars from radial velocity and transit measurements as reported in the literature. The authors have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. In addition to this HEASARC representation, the database is available in a searchable, filterable, and sortable form online through the Exoplanets Data Explorer table at <a href="http://exoplanets.org">http://exoplanets.org</a>, and the data can be plotted and explored through the Exoplanet Data Explorer plotter which is available at that web site. In their paper, the authors use the Data Explorer to generate publication-ready plots, giving three examples of the signatures of exoplanet migration and dynamical evolution: They illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the different selection biases between radial velocity and transit surveys, and that the multi-planet systems show a distinct semi-major-axis distribution from apparently singleton systems. This table was first created by the HEASARC in August 2012 based on a machine-readable version of the Exoplanet Orbit Database which was obtained from the authors' web site (<a href="http://exoplanets.org">http://exoplanets.org</a>), file exoplanets.csv. It is updated usually within a day of whenever the source file is updated. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/AJ/159/211
- Title:
- Exoplanet parameters from Kepler and K2
- Short Name:
- J/AJ/159/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present calculations of the occurrence rate of small close-in planets around low-mass dwarf stars using the known planet populations from the Kepler and K2 missions. Applying completeness corrections clearly reveals the radius valley in the maximum a posteriori occurrence rates as a function of orbital separation and planet radius. We measure the slope of the valley to be r_p,valley_{prop}F^-0.060{+/-}0.025^, which bears the opposite sign from that measured around Sun-like stars, thus suggesting that thermally driven atmospheric mass loss may not dominate the evolution of planets in the low stellar mass regime or that we are witnessing the emergence of a separate channel of planet formation. The latter notion is supported by the relative occurrence of rocky to non-rocky planets increasing from 0.5{+/-}0.1 around mid-K dwarfs to 8.5{+/-}4.6 around mid-M dwarfs. Furthermore, the center of the radius valley at 1.54{+/-}0.16R{earth} is shown to shift to smaller sizes with decreasing stellar mass, in agreement with physical models of photoevaporation, core-powered mass loss, and gas-poor formation. Although current measurements are insufficient to robustly identify the dominant formation pathway of the radius valley, such inferences may be obtained by the Transiting Exoplanet Survey Satellite with O(85000) mid-to-late M dwarfs observed with 2minutes cadence. The measurements presented herein also precisely designate the subset of planetary orbital periods and radii that should be targeted in radial velocity surveys to resolve the rocky to non-rocky transition around low-mass stars.
4370. Exoplanet radio emission
- ID:
- ivo://CDS.VizieR/J/ApJ/612/511
- Title:
- Exoplanet radio emission
- Short Name:
- J/ApJ/612/511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We predict the radio flux densities of the extrasolar planets in the current census, making use of an empirical relation - the radiometric Bode's law - determined from the five "magnetic" planets in the solar system (the Earth and the four gas giants). Radio emission from these planets results from solar wind-powered electron currents depositing energy in the magnetic polar regions. We find that most of the known extrasolar planets should emit in the frequency range 10-1000 MHz and, under favorable circumstances, have typical flux densities as large as 1mJy. We also describe an initial, systematic effort to search for radio emission in low radio frequency images acquired with the Very Large Array (VLA). The limits set by the VLA images (~300mJy) are consistent with, but do not provide strong constraints on, the predictions of the model.