- ID:
- ivo://CDS.VizieR/J/A+A/643/A112
- Title:
- CARMENES VIS RVs of 3 M dwarfs
- Short Name:
- J/A+A/643/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We announce the discovery of two planets orbiting the M dwarfs GJ 251 (0.360+/-0.015M_{sun}_) and HD 238090 (0.578+/-0.021M_{sun}_) based on CARMENES radial velocity (RV) data. In addition, we independently confirm with CARMENES data the existence of Lalande 21185 b, a planet that has recently been discovered with the SOPHIE spectrograph. All three planets belong to the class of warm or temperate super-Earths and share similar properties. The orbital periods are 14.24d, 13.67d, and 12.95d and the minimum masses are 4.0+/-0.4M_{sun}_, 6.9+/-0.9M_{sun}_, and 2.7+/-0.3M_{sun}_ for GJ 251 b, HD 238090 b, and Lalande 21185 b, respectively. Based on the orbital and stellar properties, we estimate equilibrium temperatures of 351.0+/-1.4K for GJ 251 b, 469.6+/-2.6K for HD 238090 b, and 370.1+/-6.8K for Lalande 21185 b. For the latter we resolve the daily aliases that were present in the SOPHIE data and that hindered an unambiguous determination of the orbital period. We find no significant signals in any of our spectral activity indicators at the planetary periods. The RV observations were accompanied by contemporaneous photometric observations. We derive stellar rotation periods of 122.1+/-2.2d and 96.7+/-3.7d for GJ 251 and HD 238090, respectively. The RV data of all three stars exhibit significant signals at the rotational period or its first harmonic. For GJ 251 and Lalande 21185, we also find long-period signals around 600d, and 2900d, respectively, which we tentatively attribute to long-term magnetic cycles. We apply a Bayesian approach to carefully model the Keplerian signals simultaneously with the stellar activity using Gaussian process regression models and extensively search for additional significant planetary signals hidden behind the stellar activity. Current planet formation theories suggest that the three systems represent a common architecture, consistent with formation following the core accretion paradigm.
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- ID:
- ivo://CDS.VizieR/J/ApJ/646/505
- Title:
- Catalog of nearby exoplanets
- Short Name:
- J/ApJ/646/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of nearby exoplanets. It contains the 172 known low-mass companions with orbits established through radial velocity and transit measurements around stars within 200pc. We include five previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148, and HD 164922. We update orbits for 83 additional exoplanets, including many whose orbits have not been revised since their announcement, and include radial velocity time series from the Lick, Keck, and Anglo-Australian Observatory planet searches. Both these new and previously published velocities are more precise here due to improvements in our data reduction pipeline, which we applied to archival spectra. We present a brief summary of the global properties of the known exoplanets, including their distributions of orbital semimajor axis, minimum mass, and orbital eccentricity.
- ID:
- ivo://CDS.VizieR/J/AJ/153/95
- Title:
- Catalog of Suspected Nearby Young Stars
- Short Name:
- J/AJ/153/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new nearby young moving group (NYMG) kinematic membership analysis code, LocAting Constituent mEmbers In Nearby Groups (LACEwING), a new Catalog of Suspected Nearby Young Stars, a new list of bona fide members of moving groups, and a kinematic traceback code. LACEwING is a convergence-style algorithm with carefully vetted membership statistics based on a large numerical simulation of the Solar Neighborhood. Given spatial and kinematic information on stars, LACEwING calculates membership probabilities in 13 NYMGs and three open clusters within 100 pc. In addition to describing the inputs, methods, and products of the code, we provide comparisons of LACEwING to other popular kinematic moving group membership identification codes. As a proof of concept, we use LACEwING to reconsider the membership of 930 stellar systems in the Solar Neighborhood (within 100 pc) that have reported measurable lithium equivalent widths. We quantify the evidence in support of a population of young stars not attached to any NYMGs, which is a possible sign of new as-yet-undiscovered groups or of a field population of young stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/246/4
- Title:
- Catalog of ultrawide binary stars from Gaia DR2
- Short Name:
- J/ApJS/246/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extensive and pure sample of ultrawide binary stars with separations of 0.01<~s/pc<~1 in the solar neighborhood. Using data from Gaia DR2, we define kinematic subpopulations via the systems' tangential velocities, i.e., disk-like (v_{perp},tot_<=40km/s), intermediate (v_{perp},tot_=40-85km/s), and halo-like (v_{perp},tot_>=85km/s) binaries, presuming that these velocity cuts represent a rough ordering in the binaries' age and metallicity. Through stringent cuts on astrometric precision, we can obtain pure binary samples at such wide separations with thousands of binaries in each sample. Fitting a smoothly broken power law for the separation distribution, we find that its slope at s=10^2.5-4^au is the same for all subpopulations, p(s){propto}s^{gamma}^ with {gamma}~-1.54. However, the logarithmic slope of p(s) steepens at s>~10^4^au. We find some evidences that the degree of steepening increases with the binaries' age, with a slope change of only {Delta}{gamma}~0.5 for disk-like stars, but {Delta}{gamma}>~1 for halo-like stars. This trend is contrary to what might be expected if steepening at wide separations were due to gravitational perturbations by molecular clouds or stars, which would preferentially disrupt disk binaries. If we were to interpret steepening at s>~10^4^au as a consequence of disruption by MAssive Compact Halo Objects (MACHOs), we would have to invoke a MACHO population inconsistent with other constraints. As a more plausible alternative, we propose a simple model to predict the separation distribution of wide binaries formed in dissolving star clusters. This model generically predicts {gamma}~-1.5 as observed, with steepening at larger separations due to the finite size of binaries' birth clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A90
- Title:
- Characterization of HD 108874 system
- Short Name:
- J/A+A/599/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to understand the observed physical and orbital diversity of extrasolar planetary systems, a full investigation of these objects and of their host stars is necessary. Within this field, one of the main purposes of the GAPS observing project with HARPS-N@TNG is to provide a more detailed characterisation of already known systems. In this framework we monitored the star, hosting two giant planets, HD108874, with HARPS-N for three years in order to refine the orbits, to improve the dynamical study and to search for additional low-mass planets in close orbits. We subtracted the radial velocity (RV) signal due to the known outer planets, finding a clear modulation of 40.2d period. We analysed the correlation between RV residuals and the activity indicators and modelled the magnetic activity with a dedicated code. Our analysis suggests that the 40.2d periodicity is a signature of the rotation period of the star. A refined orbital solution is provided, revealing that the system is close to a mean motion resonance of about 9:2, in a stable configuration over 1Gyr. Stable orbits for low-mass planets are limited to regions very close to the star or far from it. Our data exclude super-Earths with Msini>~5M_{earth}_ within 0.4AU and objects with Msini>~2M_{earth}_ with orbital periods of a few days. Finally we put constraints on the habitable zone of the system, assuming the presence of an exomoon orbiting the inner giant planet.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A136
- Title:
- 7 CMa system velocity curves
- Short Name:
- J/A+A/631/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a second planet orbiting the K giant star 7 CMa based on 166 high-precision radial velocities obtained with Lick, HARPS, UCLES and SONG. The periodogram analysis reveals two periodic signals of approximately 745 and 980d, associated to planetary companions. A double-Keplerian orbital fit of the data reveals two Jupiter-like planets with minimum masses M_b_sini~1.9Mj and M_c_sini~0.9Mj, orbiting at semi-major axes of a_b_~1.75au and a_c_~2.15au, respectively. Given the small orbital separation and the large minimum masses of the planets close encounters may occur within the time baseline of the observations, thus, a more accurate N-body dynamical modeling of the available data is performed. The dynamical best-fit solution leads to collision of the planets and we explore the long-term stable configuration of the system in a Bayesian framework, confirming that 13% of the posterior samples are stable for at least 10Myr. The result from the stability analysis indicates that the two-planets are trapped in a low-eccentricity 4:3 mean-motion resonance. This is only the third discovered system to be inside a 4:3 resonance, making it very valuable for planet formation and orbital evolution models.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A1
- Title:
- 55 Cnc radial velocities and photometry
- Short Name:
- J/A+A/619/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbiting a bright, nearby star the 55 Cnc system offers a rare opportunity to study a multiplanet system that has a wide range of planetary masses and orbital distances. Using two decades of photometry and spectroscopy data, we have measured the rotation of the host star and its solar-like magnetic cycle. Accounting for this cycle in our velocimetric analysis of the system allows us to revise the properties of the outermost giant planet and its four planetary companions. The innermost planet 55 Cnc e is an unusually close-in super-Earth, whose transits have allowed for detailed follow-up studies. Recent observations favor the presence of a substantial atmosphere yet its composition, and the nature of the planet, remain unknown. We combined our derived planet mass (Mp=8.0+/-0.3M_{Earth}_) with refined measurement of its optical radius derived from HST/STIS observations (Rp=1.88+/-0.03R_{Earth}_ over 530-750nm) to revise the density of 55 Cnc e (rho=6.7+/-0.4g/cm^3^). Based on these revised properties we have characterized possible interiors of 55 Cnc e using a generalized Bayesian model. We confirm that the planet is likely surrounded by a heavyweight atmosphere, contributing a few percents of the planet radius. While we cannot exclude the presence of a water layer underneath the atmosphere, this scenario is unlikely given the observations of the planet across the entire spectrum and its strong irradiation. Follow-up observations of the system in photometry and in spectroscopy over different time-scales are needed to further investigate the nature and origin of this iconic super-Earth.
- ID:
- ivo://CDS.VizieR/J/ApJ/807/23
- Title:
- Companions of RS CVn primaries. I. sig Gem
- Short Name:
- J/ApJ/807/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To measure the properties of both components of the RS Canum Venaticorum binary {sigma} Geminorum ({sigma} Gem), we directly detect the faint companion, measure the orbit, obtain model-independent masses and evolutionary histories, detect ellipsoidal variations of the primary caused by the gravity of the companion, and measure gravity darkening. We detect the companion with interferometric observations obtained with the Michigan InfraRed Combiner at Georgia State University's Center for High Angular Resolution Astronomy Array with a primary-to-secondary H-band flux ratio of 270+/-70. A radial velocity curve of the companion was obtained with spectra from the Tillinghast Reflector Echelle Spectrograph on the 1.5m Tillinghast Reflector at Fred Lawrence Whipple Observatory. We additionally use new observations from the Tennessee State University Automated Spectroscopic and Photometric Telescopes (AST and APT, respectively). From our orbit, we determine model-independent masses of the components (M1=1.28+/-0.07M_{sun}_, M2=0.73+/-0.03M_{sun}_), and estimate a system age of 5+/-1Gyr. An average of the 27 year APT light curve of {sigma} Gem folded over the orbital period (P=19.6027+/-0.0005days) reveals a quasi-sinusoidal signature, which has previously been attributed to active longitudes 180{deg} apart on the surface of {sigma} Gem. With the component masses, diameters, and orbit, we find that the predicted light curve for ellipsoidal variations due to the primary star partially filling its Roche lobe potential matches well with the observed average light curve, offering a compelling alternative explanation to the active longitudes hypothesis. Measuring gravity darkening from the light curve gives {beta}<0.1, a value slightly lower than that expected from recent theory.
- ID:
- ivo://CDS.VizieR/J/AJ/151/85
- Title:
- Companions to APOGEE stars. I.
- Short Name:
- J/AJ/151/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In its three years of operation, the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE-1) observed >14000 stars with enough epochs over a sufficient temporal baseline for the fitting of Keplerian orbits. We present the custom orbit-fitting pipeline used to create this catalog, which includes novel quality metrics that account for the phase and velocity coverage of a fitted Keplerian orbit. With a typical radial velocity precision of ~100-200 m/s, APOGEE can probe systems with small separation companions down to a few Jupiter masses. Here we present initial results from a catalog of 382 of the most compelling stellar and substellar companion candidates detected by APOGEE, which orbit a variety of host stars in diverse Galactic environments. Of these, 376 have no previously known small separation companion. The distribution of companion candidates in this catalog shows evidence for an extremely truncated brown dwarf (BD) desert with a paucity of BD companions only for systems with a<0.1-0.2 AU, with no indication of a desert at larger orbital separation. We propose a few potential explanations of this result, some which invoke this catalog's many small separation companion candidates found orbiting evolved stars. Furthermore, 16 BD and planet candidates have been identified around metal-poor ([Fe/H]<-0.5) stars in this catalog, which may challenge the core accretion model for companions >10 M_Jup_. Finally, we find all types of companions are ubiquitous throughout the Galactic disk with candidate planetary-mass and BD companions to distances of ~6 and ~16 kpc, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A122
- Title:
- CoRoT-30b and CoRoT-31b radial velocity curves
- Short Name:
- J/A+A/635/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery as well as the orbital and physical characterizations of two new transiting giant exoplanets, CoRoT-30 b and CoRoT-31 b, with the CoRoT space telescope. We analyzed two complementary data sets: photometric transit light curves measured by CoRoT, and radial velocity curves measured by the HARPS spectrometer. To derive the absolute masses and radii of the planets, we modeled the stars from available magnitudes and spectra. We find that CoRoT-30 b is a warm Jupiter on a close-to-circular 9.06-day orbit around a G3V star with a semi-major axis of about 0.08AU. It has a radius of 1.01+/-0.08R_Jup_, a mass of 2.90+/-0.22M_Jup_, and therefore a mean density of 3.45+/-0.65g/cm^3^. The hot Jupiter CoRoT-31 b is on a close to circular 4.63-day orbit around a G2 IV star with a semi-major axis of about 0.05AU. It has a radius of 1.46+/-0.30R_Jup_, a mass of 0.84+/-0.34M_Jup_, and therefore a mean density of 0.33+/-0.18g/cm^3^. Neither system seems to support the claim that stars hosting planets are more depleted in lithium. The radii of both planets are close to that of Jupiter, but they differ in mass; CoRoT-30 b is ten times denser than CoRoT-31 b. The core of CoRoT-30 b would weigh between 15 and 75 Earth masses, whereas relatively weak constraints favor no core for CoRoT-31 b. In terms of evolution, the characteristics of CoRoT-31 b appear to be compatible with the high-eccentricity migration scenario, which is not the case for CoRoT-30 b. The angular momentum of CoRoT-31 b is currently too low for the planet to evolve toward synchronization of its orbital revolution with stellar rotation, and the planet will slowly spiral-in while its host star becomes a red giant. CoRoT-30 b is not synchronized either: it looses angular momentum owing to stellar winds and is expected reach steady state in about 2Gyr. CoRoT-30 and 31, as a pair, are a truly remarkable example of diversity in systems with hot Jupiters.