- ID:
- ivo://CDS.VizieR/J/ApJ/903/L11
- Title:
- OGLE and KMTNet light curve of OGLE-2016-BLG-1928
- Short Name:
- J/ApJ/903/L11
- Date:
- 21 Mar 2022 06:18:03
- Publisher:
- CDS
- Description:
- Some low-mass planets are expected to be ejected from their parent planetary systems during early stages of planetary system formation. According to planet formation theories, such as the core accretion theory, typical masses of ejected planets should be between 0.3 and 1.0M{Earth}. Although in practice such objects do not emit any light, they may be detected using gravitational microlensing via their light-bending gravity. Microlensing events due to terrestrial-mass rogue planets are expected to have extremely small angular Einstein radii (<~1{mu}as) and extremely short timescales (<~0.1day). Here, we present the discovery of the shortest-timescale microlensing event, OGLE-2016-BLG-1928, identified to date (t_E_~0.0288day=41.5min. Thanks to the detection of finite-source effects in the light curve of the event, we were able to measure the angular Einstein radius of the lens {theta}_E_=0.842{+/-}0.064{mu}as, making the event the most extreme short-timescale microlens discovered to date. Depending on its unknown distance, the lens may be a Mars- to Earth-mass object, with the former possibility favored by the Gaia proper motion measurement of the source. The planet may be orbiting a star but we rule out the presence of stellar companions up to the projected distance of ~8.0au from the planet. Our discovery demonstrates that terrestrial-mass free-floating planets can be detected and characterized using microlensing.
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- ID:
- ivo://CDS.VizieR/J/AJ/159/262
- Title:
- OGLE/KMTnet VI bands photomerty of OGLE-2019-BLG-0551
- Short Name:
- J/AJ/159/262
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- High-cadence observations of the Galactic bulge by the microlensing surveys led to the discovery of a handful of extremely short-timescale microlensing events that can be attributed to free-floating or wide-orbit planets. Here, we report the discovery of another strong free-floating planet candidate, which was found from the analysis of the gravitational microlensing event OGLE-2019-BLG-0551. The light curve of the event is characterized by a very short duration (<~3days) and a very small amplitude (<~0.1mag). From modeling of the light curve, we find that the Einstein timescale, t_E_=0.381{+/-}0.017day, is much shorter, and the angular Einstein radius, {theta}_E_=4.35{+/-}0.34{mu}mas, is much smaller than those of typical lensing events produced by stellar-mass lenses (t_E_~20days, {theta}_E_~0.3mas), indicating that the lens is very likely to be a planetary-mass object. We conduct an extensive search for possible signatures of a companion star in the light curve of the event, finding no significant evidence for the putative host star. For the first time, we also demonstrate that the angular Einstein radius of the lens does not depend on blending in the low-magnification events with strong finite source effects.
- ID:
- ivo://CDS.VizieR/J/AJ/161/270
- Title:
- OGLE, MOA & KMTNet RI light curve of KMT-2019-BLG-1715
- Short Name:
- J/AJ/161/270
- Date:
- 16 Mar 2022 00:06:48
- Publisher:
- CDS
- Description:
- We investigate the gravitational microlensing event KMT-2019-BLG-1715, the light curve of which shows two short-term anomalies from a caustic-crossing binary-lensing light curve: one with a large deviation and the other with a small deviation. We identify five pairs of solutions, in which the anomalies are explained by adding an extra lens or source component in addition to the base binary-lens model. We resolve the degeneracies by applying a method in which the measured flux ratio between the first and second source stars is compared with the flux ratio deduced from the ratio of the source radii. Applying this method leaves a single pair of viable solutions, in both of which the major anomaly is generated by a planetary-mass third body of the lens, and the minor anomaly is generated by a faint second source. A Bayesian analysis indicates that the lens comprises three masses: a planet-mass object with ~2.6M_J_ and binary stars of K and M dwarfs lying in the galactic disk. We point out the possibility that the lens is the blend, and this can be verified by conducting high-resolution follow-up imaging for the resolution of the lens from the source.
- ID:
- ivo://CDS.VizieR/J/AJ/160/74
- Title:
- Optical and IR photometry of OGLE-2017-BLG-0406
- Short Name:
- J/AJ/160/74
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the Spitzer satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of q=7.0x10^-4^ from the light-curve modeling. The ground-only and Spitzer-"only" data each provide very strong one-dimensional (1D) constraints on the 2D microlens parallax vector {pi}_E_. When combined, these yield a precise measurement of {pi}_E_ and of the masses of the host M_host_=0.56{+/-}0.07M_{sun} and planet M_planet_=0.41{+/-}0.05M_Jup_. The system lies at a distance D_L_=5.2{+/-}0.5 kpc from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is a_{perp}_=3.5{+/-}0.3au (i.e., just over twice the snow line). The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the Gaia proper-motion measurement of the source suffers from a catastrophic 10{sigma} error.
- ID:
- ivo://CDS.VizieR/J/AJ/160/235
- Title:
- Optical photometry and RVs of TOI-481b and TOI-892b
- Short Name:
- J/AJ/160/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481b and TOI-892b have similar radii (0.99{+/-}0.01R_Jup_ and 1.07{+/-}0.02R_Jup_, respectively), and orbital periods (10.3311days and 10.6266days, respectively), but significantly different masses (1.53{+/-}0.03M_Jup versus 0.95{+/-}0.07M_Jup_, respectively). Both planets orbit metal-rich stars ([Fe/H]=+0.26{+/-}0.05dex and [Fe/H]=+0.24{+/-}0.05 for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a M_*_=1.14{+/-}0.02M_{odot}_, R_*_=1.66{+/-}0.02R_{odot}_ G-type star (Teff=5735{+/-}72K), that with an age of 6.7Gyr, is in the turn-off point of the main sequence. TOI-892 on the other hand, is a F-type dwarf star (Teff=6261{+/-}80K), which has a mass of M_*_=1.28{+/-}0.03M_{odot}_ and a radius of R_*_=1.39{+/-}0.02R_{odot}_. TOI-481b and TOI-892b join the scarcely populated region of transiting gas giants with orbital periods longer than 10days, which is important to constrain theories of the formation and structure of hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/AJ/160/207
- Title:
- OSIRIS K-band spectroscopy of {kappa} Andromedae b
- Short Name:
- J/AJ/160/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present moderate-resolution (R~4000) K-band spectra of the "super- Jupiter," {kappa}-Andromedae-b. The data were taken with the OSIRIS integral field spectrograph at Keck Observatory. The spectra reveal resolved molecular lines from H2O and CO, and are compared to a custom PHOENIX atmosphere model grid appropriate for young planetary-mass objects. We fit the data using a Markov chain Monte Carlo forward-modeling method. Using a combination of our moderate-resolution spectrum and low-resolution, broadband data from the literature, we derive an effective temperature of Teff=1950-2150K, a surface gravity of logg=3.5--4.5, and a metallicity of [M/H]=-0.2--0.0. These values are consistent with previous estimates from atmospheric modeling and the currently favored young age of the system (<50Myr). We derive a C/O ratio of 0.70_-0.24_^+0.09^ for the source, broadly consistent with the solar C/O ratio. This, coupled with the slightly subsolar metallicity, implies a composition consistent with that of the host star, and is suggestive of formation by a rapid process. The subsolar metallicity of {kappa}-Andromedae-b is also consistent with predictions of formation via gravitational instability. Further constraints on formation of the companion will require measurement of the C/O ratio of {kappa}-Andromedae-A. We also measure the radial velocity of {kappa}-Andromedae-b for the first time, with a value of -1.4{+/-}0.9km/s relative to the host star. We find that the derived radial velocity is consistent with the estimated high eccentricity of {kappa}-Andromedae-b.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A201
- Title:
- 10 parsec sample in the Gaia era
- Short Name:
- J/A+A/650/A201
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be seen and understood with precise data. This work is triggered by the most recent data release of the astrometric space mission Gaia and uses its unprecedented high precision parallax measurements to review the census of objects within 10pc. The first aim of this work was to compile all stars and brown dwarfs within 10pc observable by Gaia and compare it with the Gaia Catalogue of Nearby Stars as a quality assurance test. We complement the list to get a full 10 pc census, including bright stars, brown dwarfs, and exoplanets. We started our compilation from a query on all objects with a parallax larger than 100 mas using the Set of Identifications, Measurements, and Bibliography for Astronomical Data database (SIMBAD). We completed the census by adding companions, brown dwarfs with recent parallax measurements not in SIMBAD yet, and vetted exoplanets. The compilation combines astrometry and photometry from the recent Gaia Early Data Release 3 with literature magnitudes, spectral types, and line-of-sight velocities. We give a description of the astrophysical content of the 10pc sample. We find a multiplicity frequency of around 27%. Among the stars and brown dwarfs, we estimate that around 61% are M stars and more than half of the M stars are within the range from M3.0 V to M5.0 V. We give an overview of the brown dwarfs and exoplanets that should be detected in the next Gaia data releases along with future developments. We provide a catalogue of 540 stars, brown dwarfs, and exoplanets in 339 systems, within 10pc from the Sun. This list is as volume-complete as possible from current knowledge and it provides benchmark stars that can be used, for instance, to define calibration samples and to test the quality of the forthcoming Gaia releases. It also has a strong outreach potential.
- ID:
- ivo://CDS.VizieR/J/AJ/162/100
- Title:
- PAST. II. LAMOST-Gaia-Kepler catalog of 35835 stars
- Short Name:
- J/AJ/162/100
- Date:
- 14 Mar 2022 06:40:51
- Publisher:
- CDS
- Description:
- The Kepler telescope has discovered over 4000 planets (candidates) by searching ~200000 stars over a wide range of distance (order of kpc) in our Galaxy. Characterizing the kinematic properties (e.g., Galactic component membership and kinematic age) of these Kepler targets (including the planet candidate hosts) is the first step toward studying Kepler planets in the Galactic context, which will reveal fresh insights into planet formation and evolution. In this paper, the second part of the Planets Across the Space and Time (PAST) series, by combining the data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia and then applying the revised kinematic methods from PAST I, we present a catalog of kinematic properties (i.e., Galactic positions, velocities, and the relative membership probabilities among the thin disk, thick disk, Hercules stream, and the halo) as well as other basic stellar parameters for 35835 Kepler stars. Further analyses of the LAMOST-Gaia-Kepler catalog demonstrate that our derived kinematic age reveals the expected stellar activity-age trend. Furthermore, we find that the fraction of thin (thick) disk stars increases (decreases) with the transiting planet multiplicity (N_p_=0,1,2 and3+) and the kinematic age decreases with N_p_, which could be a consequence of the dynamical evolution of planetary architecture with age. The LAMOST-Gaia-Kepler catalog will be useful for future studies on the correlations between the exoplanet distributions and the stellar Galactic environments as well as ages.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A25
- Title:
- PDS70 VLT/SPHERE images
- Short Name:
- J/A+A/632/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PDS 70 is a young (5.4Myr), nearby (~113pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a planetary mass companion, PDS70b, within the disk cavity. Moreover, observations in H{alpha} with MagAO and MUSE revealed emission associated to PDS 70 b and to another new companion candidate, PDS70c, at a larger separation from the star. PDS 70 is the only multiple planetary system at its formation stage detected so far through direct imaging. Our aim is to confirm the discovery of the second planet PDS 70 c using SPHERE at VLT, to further characterize its physical properties, and search for additional point sources in this young planetary system. Methods. We re-analyzed archival SPHERE NIR observations and obtained new data in Y, J, H and K spectral bands for a total of four different epochs. The data were reduced using the data reduction and handling pipeline and the SPHERE data center. We then applied custom routines (e.g. ANDROMEDA and PACO) to subtract the starlight. We re-detect both PDS 70 b and c and confirm that PDS70c is gravitationally bound to the star. We estimate this second planet to be less massive than 5M_Jup_ and with a Teff around 900K. Also, it has a low gravity with log g between 3.0 and 3.5dex. In addition, a third object has been identified at short separation (~0.12") from the star and gravitationally bound to the star. Its spectrum is however very blue, so that we are probably seeing stellar light reflected by dust and our analysis seems to demonstrate that it is a feature of the inner disk. We, however, cannot completely exclude the possibility that it is a planetary mass object enshrouded by a dust envelope. In this latter case, its mass should be of the order of few tens of M_{Earth}_. Moreover, we propose a possible structure for the planetary system based on our data that, however, cannot be stable on a long timescale.
- ID:
- ivo://CDS.VizieR/J/AJ/156/227
- Title:
- Photometric observations of the K2-22 system
- Short Name:
- J/AJ/156/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 45 ground-based photometric observations of the K2-22 system collected between 2016 December and 2017 May, which we use to investigate the evolution of the transit of the disintegrating planet K2-22b. Last observed in early 2015, in these new observations we recover the transit at multiple epochs and measure a typical depth of <1.5%. We find that the distribution of our measured transit depths is comparable to the range of depths measured in observations from 2014 and 2015. These new observations also support ongoing variability in the K2-22b transit shape and time, although the overall shallowness of the transit makes a detailed analysis of these transit parameters difficult. We find no strong evidence of wavelength-dependent transit depths for epochs where we have simultaneous coverage at multiple wavelengths, although our stacked Las Cumbres Observatory data collected over days-to-months timescales are suggestive of a deeper transit at blue wavelengths. We encourage continued high-precision photometric and spectroscopic monitoring of this system in order to further constrain the evolution timescale and to aid comparative studies with the other few known disintegrating planets.
