- ID:
- ivo://CDS.VizieR/J/A+A/640/A48
- Title:
- K2-32 and K2-233 light and RV curves
- Short Name:
- J/A+A/640/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-precision planetary densities are key pieces of information necessary to derive robust atmospheric properties for extrasolar planets. Measuring precise masses is the most challenging part of this task, especially in multi-planetary systems. The ESO-K2 collaboration focuses on the follow-up of a selection of multi-planetary systems detected by the K2 mission using the HARPS instrument with this goal in mind. In this work, we measure the masses and densities of two multi-planetary systems: a four-planet near resonant chain system (K2-32) and a young (~400Myr old) planetary system consisting of three close-in small planets (K2-233). We obtained 199 new HARPS observations for K2-32 and 124 for K2-233 covering a long baseline of more than three years. We performed a joint analysis of the radial velocities and K2 photometry with PASTIS to precisely measure and constrained the properties of these planets, focusing on their masses and orbital properties. We find that K2-32 is a compact scaled-down version of the Solar System's architecture, with a small rocky inner planet (Me=2.1_-1.1_^+1.3^M_{earth}_, Pe~4.35-days) followed by an inflated Neptune-mass planet (Mb=15.0_-1.7_^+1.8^M_{earth}_, Pb~8.99-days) and two external sub-Neptunes (Mc=8.1+/-2.4M_{earth}_, Pc~20.66-days; Md=6.7+/-2.5M_{earth}_, Pd~31.72-days). K2-32 becomes one of the few multi-planetary systems with four or more planets known where all have measured masses and radii. Additionally, we constrain the masses of the three planets in the K2-233 system through marginal detection of their induced radial velocity variations. For the two inner Earth-size planets we constrain their masses at a 95% confidence level to be smaller than Mb<11.3M_{earth}_ (Pb~2.47-days), Mc<12.8M_{earth}_ (Pc~7.06-days). The outer planet is a sub-Neptune size planet with an inferred mass of Md=8.3_-4.7_^+5.2^M_{earth}_ (Md<21.1M_{earth}_, Pd~24.36-days). Our observations of these two planetary systems confirm for the first time the rocky nature of two planets orbiting a young star, with relatively short orbital periods (<7-days). They provide key information for planet formation and evolution models of telluric planets. Additionally, the Neptune-like derived masses of the three planets, K2-32 b, c, d, puts them in a relatively unexplored regime of incident flux and planet mass, which is key for transmission spectroscopy studies in the near future.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/499/5004
- Title:
- K2-111, an old system with two planets
- Short Name:
- J/MNRAS/499/5004
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on the detailed characterisation of the K2-111 planetary system with K2, WASP, and ASAS-SN photometry as well as high-resolution spectroscopic data from HARPS-N and ESPRESSO. The host, K2-111, is confirmed to be a mildly evolved (logg=4.17), iron-poor ([Fe/H]=-0.46), but alpha-enhanced ([{alpha}/Fe]=0.27), chromospherically quiet, very old thick disc G2 star. A global fit, performed by using PyORBIT shows that the transiting planet, K2-111 b, orbits with a period P_b_=5.3518+/-0.0004d, and has a planet radius of 1.82^+0.11^_-0.09_R_{Earth}_ and a mass of 5.29^+0.76^_-0.77_ M_{Earth}_, resulting in a bulk density slightly lower than that of the Earth. The stellar chemical composition and the planet properties are consistent with K2-111 b being a terrestrial planet with an iron core mass fraction lower than the Earth. We announce the existence of a second signal in the radial velocity data that we attribute to a non-transiting planet, K2-111 c, with an orbital period of 15.6785+/-0.0064 days, orbiting in near-3:1 mean-motion resonance with the transiting planet, and a minimum planet mass of 11.3+/-1.1 M_{Earth}_. Both planet signals are independently detected in the HARPS-N and ESPRESSO data when fitted separately. There are potentially more planets in this resonant system, but more well-sampled data are required to confirm their presence and physical parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/159/2
- Title:
- K2-19b and c transit times and radial velocities
- Short Name:
- J/AJ/159/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K2-19b and c were among the first planets discovered by NASA's K2 mission and together stand in stark contrast with the physical and orbital properties of the solar system planets. The planets are between the size of Uranus and Saturn at 7.0+/-0.2 R_{Earth}_ and 4.1+/-0.2 R_{Earth}_, respectively, and reside a mere 0.1% outside the nominal 3:2 mean-motion resonance. They represent a different outcome of the planet formation process than the solar system, as well as the vast majority of known exoplanets. We measured the physical and orbital properties of these planets using photometry from K2, Spitzer, and ground-based telescopes, along with radial velocities from Keck/HIRES. Through a joint photodynamical model, we found that the planets have moderate eccentricities of e~0.20 and well-aligned apsides {Delta}{omega}~0{deg}. The planets occupy a strictly nonresonant configuration: the resonant angles circulate rather than librate. This defies the predictions of standard formation pathways that invoke convergent or divergent migration, both of which predict {Delta}{omega}~180{deg} and eccentricities of a few percent or less. We measured masses of M_p,b_=32.4+/-1.7 M_{Earth}_ and M_p,c_=10.8+/-0.6 M_{Earth}_. Our measurements, with 5% fractional uncertainties, are among the most precise of any sub-Jovian exoplanet. Mass and size reflect a planet's core/envelope structure. Despite having a relatively massive core of M_core_~15 M_{Earth}_, K2-19b is envelope-rich, with an envelope mass fraction of roughly 50%. This planet poses a challenge to standard models of core-nucleated accretion, which predict that cores >~10 M_{Earth}_ will quickly accrete gas and trigger runaway accretion when the envelope mass exceeds that of the core.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A110
- Title:
- K band spectrum of beta Pictoris b
- Short Name:
- J/A+A/633/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Beta Pictoris is arguably one of the most studied stellar systems outside of our own. Some 30 years of observations have revealed a highly-structured circumstellar disk, with rings, belts, and a giant planet: beta Pictoris b. However very little is known about how this system came into being. Our objective is to estimate the C/O ratio in the atmosphere of {beta} Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on {beta} Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high- precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for beta Pic b (e=0.15^+0.05^_-0.04_). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of M=12.7+/-2.2M_{Jup}_. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical (0.43+/-0.05 vs $0.43^+0.04^_-0.03_). We argue that if the stellar C/O in beta Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment.
- ID:
- ivo://CDS.VizieR/J/AJ/157/71
- Title:
- Keck/NIRC2 astrometry for GSC 6214-210 b
- Short Name:
- J/AJ/157/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Direct-imaging exoplanet surveys have discovered a class of 5-20 M_Jup_ substellar companions at separations >100 au from their host stars, which present a challenge to planet and star formation models. Detailed analysis of the orbital architecture of these systems can provide constraints on possible formation mechanisms, including the possibility that they were dynamically ejected onto a wide orbit. We present astrometry for the wide planetary-mass companion GSC 6214-210 b (240 au; ~14 M_Jup_) obtained using NIRC2 with adaptive optics at the Keck telescope over 10 years. Our measurements achieved astrometric uncertainties of ~1 mas per epoch. We determined a relative motion of 1.12+/-0.15 mas/yr (0.61+/-0.09 km/s), the first detection of orbital motion for this companion. We compute the minimum periastron for the companion due to our measured velocity vector and derive constraints on the orbital parameters through our modified implementation of the Orbits for the Impatient rejection sampling algorithm. We find that close periastron orbits, which could indicate that the companion was dynamically scattered, are present in our posterior but have low likelihoods. For all orbits in our posterior, we assess the detectability of close-in companions that could have scattered GSC 6214-210 b from a closer orbit, and find that most potential scatterers would have been detected in previous imaging. We conclude that formation at small orbital separation and subsequent dynamical scattering through interaction with another potential close-in object is an unlikely formation pathway for this companion. We also update stellar and substellar properties for the system using the new parallax from Gaia DR2 (Cat. I/345).
- ID:
- ivo://CDS.VizieR/J/A+A/627/A165
- Title:
- KELT-9 b atmos. model transmission spectra
- Short Name:
- J/A+A/627/A165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- KELT-9 b exemplifies a newly emerging class of short-period gaseous exoplanets that tend to orbit hot, early type stars - termed ultra-hot Jupiters. The severe stellar irradiation heats their atmospheres to temperatures of 4000K, similar to temperatures of photospheres of dwarf stars. Due to the absence of aerosols and complex molecular chemistry at such temperatures, these planets offer the potential of detailed chemical characterization through transit and day-side spectroscopy. Detailed studies of their chemical inventories may provide crucial constraints on their formation process(es) and evolution history. We aim to search the optical transmission spectrum of KELT-9 b for absorption lines by metals using the cross-correlation technique. We analysed two transit observations obtained with the HARPS-N spectrograph.We used an isothermal equilibrium chemistry model to predict the transmission spectrum for each of the neutral and singly ionized atoms with atomic numbers between three and 78. Of these, we identified the elements that are expected to have spectral lines in the visible wavelength range and used those as cross-correlation templates. We detect (>5{sigma}) absorption by NaI, CrII, ScII and YII, and confirm previous detections of MgI, FeI, FeII, and TiII. In addition, we find evidence of CaI, CrI, CoI, and SrII that will require further observations to verify. The detected absorption lines are significantly deeper than predicted by our model, suggesting that the material is transported to higher altitudes where the density is enhanced compared to a hydrostatic profile, and that the material is part of an extended or outflowing envelope. There appears to be no significant blue-shift of the absorption spectrum due to a net day-to-night side wind. In particular, the strong Fe ii feature is shifted by 0.18+/-0.27km/s, consistent with zero. Using the orbital velocity of the planet we derive revised masses and radii of the star and the planet: M*= 1.978+/-0.023M_{sun}_, R*=2.178+/-0.011R_{sun}_, m_p_=2.44+/-0.70M_J_ and Rp=1.783+/-0.009R_J_.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A34
- Title:
- KELT-9b radial velocity curve
- Short Name:
- J/A+A/631/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of the GAPS project, we observed the planet-hosting star KELT-9 (A-type star, vsini~110km/s) with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. In this work we analyse the spectra and the extracted radial velocities, to constrain the physical parameters of the system and to detect the planetary atmosphere of KELT-9b. We extracted from the high-resolution optical spectra the mean stellar line profiles with an analysis based on the Least Square Deconvolution technique. Then, we computed the stellar radial velocities with a method optimized for fast rotators, by fitting the mean stellar line profile with a purely rotational profile instead of using a Gaussian function. The new spectra and analysis led us to update the orbital and physical parameters of the system, improving in particular the value of the planetary mass to Mp=2.88+/-0.35M_Jup_. We discovered an anomalous in-transit radial velocity deviation from the theoretical Rossiter- McLaughlin effect solution, calculated from the projected spin-orbit angle {lambda}=-85.78+/-0.46 degrees measured with Doppler tomography. We prove that this deviation is caused by the planetary atmosphere of KELT-9b, thus we name this effect Atmospheric Rossiter-McLaughlin effect. By analysing the magnitude of the radial velocity anomaly, we obtained information on the extension of the planetary atmosphere as weighted by the model used to retrieve the stellar mean line profiles, which is up to 1.22+/-0.02Rp. The Atmospheric Rossiter-McLaughlin effect will be observable for other exo- planets whose atmosphere has non-negligible correlation with the stellar mask used to retrieve the radial velocities, in particular ultra-hot Jupiters with iron in their atmosphere. The duration and amplitude of the effect will depend not only on the extension of the atmosphere, but also on the in-transit planetary radial velocities and on the projected rotational velocity of the parent star.
- ID:
- ivo://CDS.VizieR/J/AJ/156/234
- Title:
- KELT transit false positive catalog for TESS
- Short Name:
- J/AJ/156/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ~23"/pixel very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS) - as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3'. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with spatial resolution, cadence, and photometric precision higher than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ~450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1128 bright stars (6<V<13) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.
- ID:
- ivo://CDS.VizieR/J/AJ/158/113
- Title:
- Kepler-13AB aperture photometry
- Short Name:
- J/AJ/158/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the high-resolution imaging instrument, 'Alopeke, at the Gemini-N telescope, we obtained simultaneous two-channel time-series observations of the binary exoplanet host star Kepler13-AB. Our optical observations were obtained during a transit event of the exoplanet Kepler-13b and light curves were produced using both speckle interferometric and aperture photometry techniques. Both techniques confirm that the transiting object orbits the star Kepler-13A while different transit depths are seen across the optical wavelength range, being ~2 times deeper in the blue. These measurements, as well as mass determinations in the literature, are consistent with Kepler-13b being a highly irradiated gas giant with a bloated atmosphere. Our observations highlight the ability of high-resolution speckle imaging to not only assess binarity in exoplanet host stars but robustly determine which of the stars the transiting object actually orbits.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2634
- Title:
- Kepler and K2 best candidates for planets
- Short Name:
- J/MNRAS/465/2634
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A crucial step in planet hunting surveys is to select the best candidates for follow-up observations, given limited telescope resources. This is often performed by human 'eyeballing', a time consuming and statistically awkward process. Here, we present a new, fast machine learning technique to separate true planet signals from astrophysical false positives. We use self-organizing maps (SOMs) to study the transit shapes of Kepler and K2 known and candidate planets. We find that SOMs are capable of distinguishing known planets from known false positives with a success rate of 87.0 per cent, using the transit shape alone. Furthermore, they do not require any candidate to be dispositioned prior to use, meaning that they can be used early in a mission's lifetime. A method for classifying candidates using a SOM is developed, and applied to previously unclassified members of the Kepler Objects of Interest (KOI) list as well as candidates from the K2 mission. The method is extremely fast, taking minutes to run the entire KOI list on a typical laptop. We make PYTHON code for performing classifications publicly available, using either new SOMs or those created in this work. The SOM technique represents a novel method for ranking planetary candidate lists, and can be used both alone or as part of a larger autovetting code.
