- ID:
- ivo://CDS.VizieR/J/A+A/602/A88
- Title:
- 5 M dwarfs radial velocity curves
- Short Name:
- J/A+A/602/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a dozen super-Earths and Earth-mass planets (msini<=10M_{sun}_) around M dwarfs, with a well understood selection function. This well defined sample informs on their frequency of occurrence and on the distribution of their orbital parameters, and therefore already constrains our understanding of planetary formation. The subset of these low-mass planets that were found within the habitable zone of their host star also provide prized targets for future atmospheric biomarkers searches. We are working to extend this planetary sample to lower masses and longer periods through dense and long-term monitoring of the radial velocity of a small M dwarf sample. We obtained large numbers of HARPS spectra for the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628 and GJ 3293, from which we derived radial velocities (RVs) and spectroscopic activity indicators. We searched them for variabilities, periodicities, Keplerian modulations and correlations, and attribute the radial-velocity variations to combinations of planetary companions and stellar activity. We detect 12 planets, of which 9 are new with masses ranging from 1.17 to 10.5M_{sun}_. Those planets have relatively short orbital periods (P<40d), except two of them with periods of 217.6 and 257.8 days. Among these systems, GJ 273 harbor two planets with masses close to the one of the Earth. With a distance of 3.8 parsec only, GJ 273 is the second nearest known planetary system - after Proxima Centauri - with a planet orbiting the circumstellar habitable zone.
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- ID:
- ivo://CDS.VizieR/J/A+A/537/A67
- Title:
- MESS: Multi-purpose Exoplanet Simulation System
- Short Name:
- J/A+A/537/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high number of planet discoveries made in the last years provides a good sample for statistical analysis, leading to some clues on the distributions of planet parameters, like masses and periods, at least in close proximity to the host star. We likely need to wait for the extremely large telescopes (ELTs) to have an overall view of the extrasolar planetary systems. In this context it would be useful to have a tool that can be used for the interpretation of the present results, and also to predict what the outcomes would be of the future instruments. For this reason we built MESS: a Monte Carlo simulation code which uses either the results of the statistical analysis of the properties of discovered planets, or the results of the planet formation theories, to build synthetic planet populations fully described in terms of frequency, orbital elements and physical properties. They can then be used to either test the consistency of their properties with the observed population of planets given different detection techniques or to actually predict the expected number of planets for future surveys. In addition to the code description, we present here some of its applications to actually probe the physical and orbital properties of a putative companion within the circumstellar disk of a given star and to test constrain the orbital distribution properties of a potential planet population around the members of the TW Hydrae association. Finally, using in its predictive mode, the synergy of future space and ground-based telescopes instrumentation has been investigated to identify the mass-period parameter space that will be probed in future surveys for giant and rocky planets.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A108
- Title:
- 150MHz emission from exoplanets
- Short Name:
- J/A+A/562/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ongoing radio continuum TIFR GMRT Sky Survey (TGSS) using the Giant Metrewave Radio Telescope (GMRT) at 150MHz offers an unprecedented opportunity to undertake a fairly deep search for low-frequency radio emission from nearby extrasolar planets. Currently TGSS images are available for a little over a steradian, encompassing 175 confirmed exoplanetary systems. We have searched for their radio counterparts in the TGSS (150MHz), supplemented with a search in the NRAO VLA Sky Survey (NVSS) and the VLA FIRST survey at 1.4GHz. For 171 planetary systems, we find no evidence of radio emission in the TGSS maps, placing a 3{sigma} upper limit between 8.7mJy and 136mJy (median ~24.8mJy) at 150MHz.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A129
- Title:
- Mimas and Enceladus Cassini ISS astrometry
- Short Name:
- J/A+A/551/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide the Cassini ISS astrometric observations of the Saturnian satellites Mimas and Enceladus. The observations were taken over 6 years. Observation residuals were compared to JPL ephemerides SAT317 and SAT351, showing that the observation error is between 3 and 4 kilometers.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A29
- Title:
- MIR brightness contrast of Saturn's rings
- Short Name:
- J/A+A/599/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the mid-infrared (MIR) characteristics of Saturn's rings. We collected and analyzed MIR high spatial resolution images of Saturn's rings obtained in January 2008 and April 2005 with COMICS mounted on Subaru Telescope, and investigated the spatial variation in the surface brightness of the rings in multiple bands in the MIR. We also composed the spectral energy distributions (SEDs) of the C, B, and A rings and the Cassini Division, and estimated the temperatures of the rings from the SEDs assuming the optical depths. We find that the C ring and the Cassini Division were warmer than the B and A rings in 2008, which could be accounted for by their lower albedos, lower optical depths, and smaller self-shadowing effect. We also find that the C ring and the Cassini Division were considerably brighter than the B and A rings in the MIR in 2008 and the radial contrast of the ring brightness is the inverse of that in 2005, which is interpreted as a result of a seasonal effect with changing elevations of the sun and observer above the ring plane.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A102
- Title:
- MOA-2007-BLG-387Lb light curve I band
- Short Name:
- J/A+A/529/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07M_{sun}_<M_host_<0.49M_{sum}_ at 90% confidence. The planet-star mass ratio q=0.0132+/-0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is m_p_=2.6 Jupiter masses for the median host mass, M=0.19M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/47
- Title:
- Model atmospheres of irradiated exoplanets
- Short Name:
- J/ApJ/813/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many parameters constraining the spectral appearance of exoplanets are still poorly understood. We therefore study the properties of irradiated exoplanet atmospheres over a wide parameter range including metallicity, C/O ratio and host spectral type. We calculate a grid of 1-d radiative-convective atmospheres and emission spectra. We perform the calculations with our new Pressure-Temperature Iterator and Spectral Emission Calculator for Planetary Atmospheres (PETIT) code, assuming chemical equilibrium. The atmospheric structures and spectra are made available online. We find that atmospheres of planets with C/O ratios ~1 and Teff>~1500K can exhibit inversions due to heating by the alkalis because the main coolants CH_4_, H_2_O and HCN are depleted. Therefore, temperature inversions possibly occur without the presence of additional absorbers like TiO and VO. At low temperatures we find that the pressure level of the photosphere strongly influences whether the atmospheric opacity is dominated by either water (for low C/O) or methane (for high C/O), or both (regardless of the C/O). For hot, carbon-rich objects this pressure level governs whether the atmosphere is dominated by methane or HCN. Further we find that host stars of late spectral type lead to planetary atmospheres which have shallower, more isothermal temperature profiles. In agreement with prior work we find that for planets with Teff<1750K the transition between water or methane dominated spectra occurs at C/O~0.7, instead of ~1, because condensation preferentially removes oxygen.
- ID:
- ivo://CDS.VizieR/J/AJ/153/93
- Title:
- MOST photometry of Proxima
- Short Name:
- J/AJ/153/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of Proxima Centauri's radial velocities recently led Anglada-Escude et al. to claim the presence of a low-mass planet orbiting the Sun's nearest star once every 11.2 days. Although the a priori probability that Proxima b transits its parent star is just 1.5%, the potential impact of such a discovery would be considerable. Independent of recent radial velocity efforts, we observed Proxima Centauri for 12.5 days in 2014 and 31 days in 2015 with the Microwave and Oscillations of Stars space telescope. We report here that we cannot make a compelling case that Proxima b transits in our precise photometric time series. Imposing an informative prior on the period and phase, we do detect a candidate signal with the expected depth. However, perturbing the phase prior across 100 evenly spaced intervals reveals one strong false positive and one weaker instance. We estimate a false-positive rate of at least a few percent and a much higher false-negative rate of 20%-40%, likely caused by the very high flare rate of Proxima Centauri. Comparing our candidate signal to HATSouth ground-based photometry reveals that the signal is somewhat, but not conclusively, disfavored (1{sigma}-2{sigma}), leading us to argue that the signal is most likely spurious. We expect that infrared photometric follow-up could more conclusively test the existence of this candidate signal, owing to the suppression of flare activity and the impressive infrared brightness of the parent star.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A85
- Title:
- M67 stars radial velocities
- Short Name:
- J/A+A/603/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a seven-year-long radial velocity survey of a sample of 88 main-sequence and evolved stars to reveal signatures of Jupiter-mass planets in the solar-age and solar-metallicity open cluster M67. We analysed precise radial velocity (RV) measurements obtained with five different instruments. We conducted Monte Carlo simulations to estimate the occurrence rate of giant planets in our radial velocity survey. All the planets previously announced in this RV campaign with their properties are summarised: 3 hot Jupiters around the main-sequence stars YBP1194, YBP1514, and YBP401, and 1 giant planet around the evolved star S364. Two additional planet candidates around the stars YBP778 and S978 are also analysed. We discuss stars that exhibit large RV variability or trends individually. We find an occurrence of giant planets of ~18.0% in a selected period-mass range. This frequency is slightly higher but consistent within the errors with the estimate for the field stars, leading to the general conclusion that open cluster and field statistics agree. However, we find that the rate of hot Jupiters in the cluster (~5.7%) is substantially higher than in the field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1393
- Title:
- Multi-band light curve of WASP-36
- Short Name:
- J/MNRAS/459/1393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broad-band photometry of five transits in the planetary system WASP-36, totaling 17 high-precision light curves. Four of the transits were simultaneously observed in four passbands (g', r', i', z'), using the telescope-defocussing technique, and achieving scatters of less than 1 mmag per observation. We used these data to improve the measured orbital and physical properties of the system, and obtain an optical transmission spectrum of the planet. We measured a decreasing radius from bluer to redder passbands with a confidence level of more than 5 sigma. The radius variation is roughly 11 pressure scale heights between the g' and the z' bands. This is too strong to be Rayleigh scattering in the planetary atmosphere, and implies the presence of a species which absorbs strongly at bluer wavelengths.