- ID:
- ivo://CDS.VizieR/J/A+A/658/A115
- Title:
- Proxima Cen ESPRESSO RV and FWHM
- Short Name:
- J/A+A/658/A115
- Date:
- 21 Feb 2022 11:58:12
- Publisher:
- CDS
- Description:
- Proxima Centauri is the closest star to the Sun. This small, low-mass, mid M dwarf is known to host an Earth-mass exoplanet with an orbital period of 11.2 days within the habitable zone, as well as a long-period planet candidate with an orbital period of close to 5yr. We report on the analysis of a large set of observations taken with the ESPRESSO spectrograph at the aimed at a thorough evaluation of the presence of a third low-mass planetary companion, which started emerging during a previous campaign. Radial velocities (RVs) were calculated using both a cross-correlation function (CCF) and a template matching approach. The RV analysis includes a component to model Proxima`s activity using a Gaussian process (GP). We use the CCF's full width at half maximum to help constrain the GP, and we study other simultaneous observables as activity indicators in order to assess the nature of any potential RV signals. We detect a signal at 5.12+/-0.04 days with a semi-amplitude of 39+/-7cm/s. The analysis of subsets of the ESPRESSO data, the activity indicators, and chromatic RVs suggest that this signal is not caused by stellar variability but instead by a planetary companion with a minimum mass of 0.26+/-0.05M_{sun}_ (about twice the mass of Mars) orbiting at 0.029 au from the star. The orbital eccentricity is well constrained and compatible with a circular orbit.
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- ID:
- ivo://CDS.VizieR/J/A+A/639/A77
- Title:
- Proxima Cen RV, FWHM and fluxes
- Short Name:
- J/A+A/639/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet. We aimed to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision. We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26cm/s. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals. We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218+/-0.029-days, with a minimum mass of 1.29+/-0.13Me. In the combined dataset we measure a period of 11.18427+/-0.00070 days with a minimum mass of 1.173+/-0.086Me. We get a clear measurement of the stellar rotation period (87+/-12d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2-days signal. We find some evidence for the presence of a second short-period signal, at 5.15-days with a semi-amplitude of only 40cm/s. If caused by a planetary companion, it would correspond to a minimum mass of 0.29+/-0.08Me. We find that for the case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6Me at periods shorter than 50-days.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A147
- Title:
- Python Mie Doubling-Adding Programme
- Short Name:
- J/A+A/616/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PyMieDAP (the Python Mie Doubling-Adding Programme) is a Python-based tool for computing the total linearly and circularly polarized fluxes of incident unpolarized sunlight or starlight that is reflected by solar system planets or moons, respectively, or by exoplanets at a range of wavelengths. The radiative transfer computations are based on an doubling-adding Fortran algorithm and fully include polarization for all orders of scattering. The model (exo)planets are described by a model atmosphere composed of a stack of homogeneous layers containing gas and/or aerosol and/or cloud particles bounded below by an isotropically depolarizing surface (that is optionally black). The reflected light can be computed spatially resolved and/or disk-integrated. Spatially resolved signals are mostly representative for observations of solar system planets (or moons), while disk-integrated signals are mostly representative for exoplanet observations. PyMieDAP is modular and flexible, and allows users to adapt and optimize the code according to their needs. PyMieDAP keeps options open for connections with external programs and for future additions and extensions. In this paper, we describe the radiative transfer algorithm that PyMieDAP is based on and the principal functionalities of the code. We also provide benchmark results of PyMieDAP that can be used for testing its installation and for comparison with other codes. PyMieDAP is available online under the GNU GPL license at http://gitlab.com/loic.cg.rossi/pymiedap
- ID:
- ivo://CDS.VizieR/J/AJ/157/100
- Title:
- Radial velocities and bisector spans for K2-287
- Short Name:
- J/AJ/157/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of K2-287b, a Saturn mass planet orbiting a G-dwarf with a period of P~15 days. First uncovered as a candidate using K2 campaign 15 data, follow-up photometry and spectroscopy were used to determine a mass M_P_=0.317+/-0.026 M_J_, radius R_P_=0.833+/-0.013 R_J_, period P=14.893291+/-0.000025 days, and eccentricity e=0.476+/-0.026. The host star is a metal-rich V=11.410+/-0.129 mag G-dwarf for which we estimate a mass M_*_=1.056_-0.021_^+0.022^ M_{sun}__, radius R_*_=1.070+/-0.010 R_{sun}_, metallicity [Fe/H]=0.20+/-0.05, and T_eff_=5673+/-75 K. This warm eccentric planet with a time-averaged equilibrium temperature of T_eq_~800 K adds to the small sample of giant planets orbiting nearby stars whose structure is not expected to be affected by stellar irradiation. Follow-up studies on the K2-287 system could help constrain theories of planet migration in close-in orbits.
- ID:
- ivo://CDS.VizieR/J/AJ/154/188
- Title:
- Radial velocities and photometry of K2-114&K2-115
- Short Name:
- J/AJ/154/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first results from a search for transiting warm Jupiter exoplanets-gas giant planets receiving stellar irradiation below about 10^8^ erg/s/cm^2^, equivalent to orbital periods beyond about 10 days around Sun-like stars. We have discovered two transiting warm Jupiter exoplanets initially identified as transiting candidates in K2 photometry. K2-114b has a mass of 1.85_-0.22_^+0.23^ M_J_, a radius of 0.942_-0.020_^+0.032^ R_J_, and an orbital period of 11.4 days. K2-115b has a mass of 0.84_-0.20_^+0.18^ M_J_, a radius of 1.115_-0.061_^+0.057^ R_J_, and an orbital period of 20.3 days. Both planets are among the longest-period transiting gas giant planets with a measured mass, and they are orbiting relatively old host stars. Both planets are not inflated, as their radii are consistent with theoretical expectations. Their position in the planet radius-stellar irradiation diagram is consistent with the scenario where the radius-irradiation correlation levels off below about 10^8^ erg/s/cm^2^, suggesting that for warm Jupiters stellar irradiation does not play a significant role in determining the planet radius. We also report our identification of another K2 transiting warm Jupiter candidate, EPIC 212504617, as a false positive.
- ID:
- ivo://CDS.VizieR/J/AJ/158/181
- Title:
- Radial velocities and S-index values for HR 5183
- Short Name:
- J/AJ/158/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on two decades of radial velocity (RV) observations using Keck/High Resolution Echelle Spectrometer (HIRES) and McDonald/Tull, and more recent observations using the Automated Planet Finder, we found that the nearby star HR 5183 (HD 120066) hosts a 3 M_J_ minimum mass planet with an orbital period of 74_-22_^+43^ yr. The orbit is highly eccentric (e~0.84), shuttling the planet from within the orbit of Jupiter to beyond the orbit of Neptune. Our careful survey design enabled high cadence observations before, during, and after the planet's periastron passage, yielding precise orbital parameter constraints. We searched for stellar or planetary companions that could have excited the planet's eccentricity, but found no candidates, potentially implying that the perturber was ejected from the system. We did identify a bound stellar companion more than 15000 au from the primary, but reasoned that it is currently too widely separated to have an appreciable effect on HR 5183 b. Because HR 5183 b's wide orbit takes it more than 30 au (1") from its star, we also explored the potential of complimentary studies with direct imaging or stellar astrometry. We found that a Gaia detection is very likely, and that imaging at 10 {mu}m is a promising avenue. This discovery highlights the value of long-baseline RV surveys for discovering and characterizing long-period, eccentric Jovian planets. This population may offer important insights into the dynamical evolution of planetary systems containing multiple massive planets.
- ID:
- ivo://CDS.VizieR/J/AJ/157/192
- Title:
- Radial velocities and transit times for KOI 4
- Short Name:
- J/AJ/157/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of thousands of planetary systems by Kepler has demonstrated that planets are ubiquitous. However, a major challenge has been the confirmation of Kepler planet candidates, many of which still await confirmation. One of the most enigmatic examples is KOI 4.01, Kepler's first discovered planet candidate detection (as KOI 1.01, 2.01, and 3.01 were known prior to launch). Here we present the confirmation and characterization of KOI 4.01 (now Kepler-1658), using a combination of asteroseismology and radial velocities. Kepler-1658 is a massive, evolved subgiant (M_*_=1.45+/-0.06 M_{sun}_, R_*_=2.89+/-0.12 R_{sun}_) hosting a massive (M_p_=5.88+/-0.47 M_J_, R_p_=1.07+/-0.05 R_J_) hot Jupiter that orbits every 3.85 days. Kepler-1658 joins a small population of evolved hosts with short-period (~<100 days) planets and is now the closest known planet in terms of orbital period to an evolved star. Because of its uniqueness and short orbital period, Kepler-1658 is a new benchmark system for testing tidal dissipation and hot Jupiter formation theories. Using all four years of the Kepler data, we constrain the orbital decay rate to be P=<-0.42 s/yr, corresponding to a strong observational limit of Q'_*_>=4.826x10^3^ for the tidal quality factor in evolved stars. With an effective temperature of T_eff_~6200 K, Kepler-1658 sits close to the spin-orbit misalignment boundary at ~6250 K, making it a prime target for follow-up observations to better constrain its obliquity and to provide insight into theories for hot Jupiter formation and migration.
- ID:
- ivo://CDS.VizieR/J/AJ/154/122
- Title:
- Radial velocities for the HD 3167 system
- Short Name:
- J/AJ/154/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 3167 is a bright (V=8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02+/-0.38 M_{earth}_ for HD 3167 b, a hot super-Earth with a likely rocky composition ({rho}_b_=5.60_-1.43_^+2.15^ g/cm^3^), and 9.80_-1.24_^+1.30^ M_{earth}_ for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement ({rho}_c_=1.97_-0.59_^+0.94^ g/cm^3^). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509+/-0.045 d (between planets b and c) and a minimum mass of 6.90+/-0.71 M_{earth}_. We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.3{deg} because we do not observe transits of planet d. From 1.3{deg} to 40{deg}, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time. From 40{deg} to 60{deg}, Kozai-Lidov oscillations increase the system's instability, but it can remain stable for up to 100 Myr. Above 60{deg}, the system is unstable. HD 3167 promises to be a fruitful system for further study and a preview of the many exciting systems expected from the upcoming NASA TESS mission.
- ID:
- ivo://CDS.VizieR/J/AJ/154/181
- Title:
- Radial velocities for the star HD 34445
- Short Name:
- J/AJ/154/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new precision radial velocity (RV) data set that reveals a multi-planet system orbiting the G0V star HD 34445. Our 18-year span consists of 333 precision RV observations, 56 of which were previously published and 277 of which are new data from the Keck Observatory, Magellan at Las Campanas Observatory, and the Automated Planet Finder at Lick Observatory. These data indicate the presence of six planet candidates in Keplerian motion about the host star with periods of 1057, 215, 118, 49, 677, and 5700 days, and minimum masses of 0.63, 0.17, 0.1, 0.05, 0.12, and 0.38 MJ, respectively. The HD 34445 planetary system, with its high degree of multiplicity, its long orbital periods, and its induced stellar RV half-amplitudes in the range 2 m/s~<K~<5 m/s is fundamentally unlike either our own solar system (in which only Jupiter and Saturn induce significant reflex velocities for the Sun), or the Kepler multiple-transiting systems (which tend to have much more compact orbital configurations).
- ID:
- ivo://CDS.VizieR/J/AJ/155/112
- Title:
- Radial velocities & light curves for HATS-43-HATS-46
- Short Name:
- J/AJ/155/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four short-period extrasolar planets transiting moderately bright stars from photometric measurements of the HATSouth network coupled to additional spectroscopic and photometric follow-up observations. While the planet masses range from 0.26 to 0.90 M_J_, the radii are all approximately a Jupiter radii, resulting in a wide range of bulk densities. The orbital period of the planets ranges from 2.7 days to 4.7 days, with HATS-43b having an orbit that appears to be marginally non-circular (e=0.173+/-0.089). HATS-44 is notable for having a high metallicity ([Fe/H]=0.320+/-0.071). The host stars spectral types range from late F to early K, and all of them are moderately bright (13.3<V<14.4), allowing the execution of future detailed follow-up observations. HATS-43b and HATS-46b, with expected transmission signals of 2350 ppm and 1500 ppm, respectively, are particularly well suited targets for atmospheric characterization via transmission spectroscopy.
