- ID:
- ivo://CDS.VizieR/J/A+A/539/A102
- Title:
- HD 209458 and HD 189733 theoretical spectra
- Short Name:
- J/A+A/539/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/511/A45
- Title:
- HD 147018, 171238 and 204313 radial velocities
- Short Name:
- J/A+A/511/A45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of a double planetary system around HD140718 as well as the discovery of two long period and massive planets orbiting HD171238 and HD204313. Those discoveries were made with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory, Chile. The planetary system orbiting the nearby G9 dwarf HD147018 is composed of an eccentric inner planet (e=0.47) with twice the mass of Jupiter (2.1M_Jup_) and with an orbital period of 44.24-days. The outer planet is even more massive (6.6M_Jup_) with a slightly eccentric orbit (e=0.13) and a period of 1008-days. The planet orbiting HD171238 has a minimum mass of 2.6M_Jup_, a period of 1523-days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5AU. The last planet, HD204313 b, is a 4.0 M_Jup_-planet with a period of 5.3-years and has a low eccentricity (e=0.13). It orbits a G5 dwarfs at 3.1AU. The three parent stars are metal rich, which further strengthened the case that massive planets tend to form around metal rich stars.
- ID:
- ivo://CDS.VizieR/J/A+A/375/L27
- Title:
- HD 80606b, a planet on an extremely elongated orbit
- Short Name:
- J/A+A/375/L27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here we list the measured equivalent widths we used for estimating the stellar atmospheric parameters of the two components of the visual binary HD 80606-HD 80607. We also list our 61 individual radial velocity measurements for HD 80606. The radial-velocity measurements were obtained using the HIRES spectrograph mounted on the KECK1 10-m Telescope at the KECK Observatory (Hawaii, USA) and the ELODIE spectrograph mounted on the 1.93-m Telescope at Observatoire de Haute-Provence (France). The equivalent widths measurements for HD 80606 and HD 80607 were obtained using two additional high signal-to-noise HIRES spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A103
- Title:
- HD20794 HARPS radial velocities
- Short Name:
- J/A+A/605/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We proceed by disentangling the Keplerian signals from correlated noise and activity-induced variability. We diagnose the noise using the differences between radial velocities measured at different wavelength ranges, so-called "differential radial velocities", as well as the combination of radial velocities measured for other stars to account for instrumental effects. We apply this method to the radial velocities measured by HARPS, and identify four signals at 18, 89, 147 and 330d. The two signals at periods of 18 and 89d are previously reported and are better quantified in this work. The signal at a period of about 147d is reported for the first time, and corresponds to a super-Earth with a minimum mass of 4.59 Earth mass located 0.51AU from HD20794. We also find a significant signal at a period of about 330d corresponding to a super-Earth or Neptune in the habitable zone. Since this signal is close to the annual sampling period and significant periodogram power in some noise proxies are found close to this signal, further observations and analyses are required to confirm it. The analyses of the eccentricity and consistency of signals provide weak evidence for the existence of the previously reported 43d signal and a new signal at a period of about 11.9d with a semi amplitude of 0.4m/s. We find that the detection of a number of signals with radial velocity variations around 0.5m/s likely caused by low mass planet candidates demonstrates the important role of noise modeling in searching for Earth analogs.
- ID:
- ivo://CDS.VizieR/J/A+A/636/L6
- Title:
- HD 158259 SOPHIE radial velocities
- Short Name:
- J/A+A/636/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since 2011, the SOPHIE spectrograph has been used to search for Neptunes and super-Earths in the northern hemisphere. As part of this observational program, 290 radial velocity measurements of the 6.4 V magnitude star HD 158259 were obtained. Additionally, TESS photometric measurements of this target are available. We present an analysis of the SOPHIE data and compare our results with the output of the TESS pipeline. The radial velocity data, ancillary spectroscopic indices, and ground-based photometric measurements were analyzed with classical and l_1_ periodograms. The stellar activity was modeled as a correlated Gaussian noise and its impact on the planet detection was measured with a new technique. The SOPHIE data support the detection of five planets, each with msini~=6M_{Earth}_, orbiting HD 158259 in 3.4, 5.2, 7.9, 12, and 17.4 days. Though a planetary origin is strongly favored, the 17.4 d signal is classified as a planet candidate due to a slightly lower statistical significance and to its proximity to the expected stellar rotation period. The data also present low frequency variations, most likely originating from a magnetic cycle and instrument systematics. Furthermore, the TESS pipeline reports a significant signal at 2.17 days corresponding to a planet of radius ~=1.2R_{Earth}_. A compatible signal is seen in the radial velocities, which confirms the detection of an additional planet and yields a ~=2M_{Earth}_ mass estimate. We find a system of five planets and a strong candidate near a 3:2 mean motion resonance chain orbiting HD 158259. The planets are found to be outside of the two and three body resonances.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/97
- Title:
- HeI 5876 & 10830{AA} EWs of solar-type stars
- Short Name:
- J/ApJ/839/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Simultaneous, high-quality measurements of the neutral helium triplet features at 5876{AA} and 10830{AA} in a sample of solar-type stars are presented. The observations were made with ESO telescopes at the La Silla Paranal Observatory under program ID 088.D-0028(A) and MPG Utility Run for Fiber Extended-range Optical Spectrograph 088.A-9029(A). The equivalent widths of these features combined with chromospheric models are utilized to infer the fractional area coverage, or filling factor, of magnetic regions outside of spots. We find that the majority of the sample is characterized by filling factors less than unity. However, discrepancies occur among the coolest K-type and the warmest and most rapidly rotating F-type dwarf stars. We discuss these apparently anomalous results and find that in the case of K-type stars, they are an artifact of the application of chromospheric models best suited to the Sun than to stars with significantly lower Teff. The case of the F-type rapid rotators can be explained by the measurement uncertainties of the equivalent widths, but they may also be due to a non-magnetic heating component in their atmospheres. With the exceptions noted above, preliminary results suggest that the average heating rates in the active regions are the same from one star to the other, differing in the spatially integrated, observed level of activity due to the area coverage. Hence, differences in activity in this sample are mainly due to the filling factor of active regions.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A21
- Title:
- High contrast images of NZ Lup
- Short Name:
- J/A+A/625/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planetary systems hold the imprint of the formation and of the evolution of planets especially at young ages, and in particular at the stage when the gas has dissipated leaving mostly secondary dust grains. The dynamical perturbation of planets in the dust distribution can be revealed with high-contrast imaging in a variety of structures. SPHERE, the high-contrast imaging device installed at the VLT, was designed to search for young giant planets in long period, but is also able to resolve fine details of planetary systems at the scale of astronomical units in the scattered-light regime. As a young and nearby star, NZ Lup was observed in the course of the SPHERE survey. A debris disk had been formerly identified with HST/NICMOS. We observed this system in the near-infrared with the camera in narrow and broad band filters and with the integral field spectrograph. High contrasts are achieved by the mean of pupil tracking combined with angular differential imaging algorithms. The high angular resolution provided by SPHERE allows us to reveal a new feature in the disk which is interpreted as a superimposition of two belts of planetesimals located at stellocentric distances of ~85 and ~115au, and with a mutual inclination of about 5{deg}. Despite the very high inclination of the disk with respect to the line of sight, we conclude that the presence of a gap, that is, a void in the dust distribution between the belts, is likely. We discuss the implication of the existence of two belts and their relative inclination with respect to the presence of planets.
- ID:
- ivo://CDS.VizieR/J/AJ/162/89
- Title:
- HIRES radial velocity follow up for Kepler-129
- Short Name:
- J/AJ/162/89
- Date:
- 14 Mar 2022 06:24:52
- Publisher:
- CDS
- Description:
- We present the discovery of Kepler-129d (P_d_=7.2_-0.3_^+0.4^yr, m_sini_d__=8.3_-0.7_^+1.1^M_Jup_, e_d_=0.15_-0.05_^+0.07^) based on six years of radial-velocity observations from Keck/HIRES. Kepler-129 also hosts two transiting sub-Neptunes: Kepler-129b (P_b_= 15.79days, r_b_=2.40{+/-}0.04R{Earth}) and Kepler-129c (P_c_=82.20days, r_c_=2.52{+/-}0.07R{Earth}) for which we measure masses of m_b_<20M{Earth} and m_c_=43_-12_^+13^M{Earth}. Kepler-129 is a hierarchical system consisting of two tightly packed inner planets and a massive external companion. In such a system, two inner planets precess around the orbital normal of the outer companion, causing their inclinations to oscillate with time. Based on an asteroseismic analysis of Kepler data, we find tentative evidence that Kepler-129b and c are misaligned with stellar spin axis by >~38{deg}, which could be torqued by Kepler-129 d if it is inclined by >~19{deg} relative to inner planets. Using N-body simulations, we provide additional constraints on the mutual inclination between Kepler-129d and inner planets by estimating the fraction of time during which two inner planets both transit. The probability that two planets both transit decreases as their misalignment with Kepler-129d increases. We also find a more massive Kepler-129c enables the two inner planets to become strongly coupled and more resistant to perturbations from Kepler-129d. The unusually high mass of Kepler-129c provides a valuable benchmark for both planetary dynamics and interior structure, since the best-fit mass is consistent with this 2.5R{Earth} planet having a rocky surface.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A121
- Title:
- Identification of metal-poor stars with ANN
- Short Name:
- J/A+A/556/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. We search for metal-poor stars using the artificial neural network (ANN) and extend its usage to determine absolute magnitudes. We have constructed a library of 167 medium-resolution stellar spectra (R~1200) covering the stellar temperature range of 4200 to 8000K, logg range of 0.5 to 5.0, and [Fe/H] range of -3.0 to dex. This empirical spectral library was used to train ANNs, yielding an accuracy of 0.3dex in [Fe/H], 200K in temperature, and 0.3dex in logg. We found that the independent calibrations of near-solar metallicity stars and metal-poor stars decreases the errors in Teff and logg by nearly a factor of two.
- ID:
- ivo://CDS.VizieR/J/AJ/157/202
- Title:
- IRAC fluxes of the ID8 and P1121 systems
- Short Name:
- J/AJ/157/202
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The most dramatic phases of terrestrial planet formation are thought to be oligarchic and chaotic growth, on timescales of up to 100-200 Myr, when violent impacts occur between large planetesimals of sizes up to protoplanets. Such events are marked by the production of large amounts of debris, as has been observed in some exceptionally bright and young debris disks (termed extreme debris disks). Here we report five years of Spitzer measurements of such systems around two young solar-type stars: ID8 and P1121. The short-term (weekly to monthly) and long-term (yearly) disk variability is consistent with the aftermaths of large impacts involving large asteroid-sized bodies. We demonstrate that an impact-produced clump of optically thick dust, under the influence of the dynamical and viewing geometry effects, can produce short-term modulation in the disk light curves. The long-term disk flux variation is related to the collisional evolution within the impact-produced fragments once released into a circumstellar orbit. The time-variable behavior observed in the P1121 system is consistent with a hypervelocity impact prior to 2012 that produced vapor condensates as the dominant impact product. Two distinct short-term modulations in the ID8 system suggest two violent impacts at different times and locations. Its long-term variation is consistent with the collisional evolution of two different populations of impact-produced debris dominated by either vapor condensates or escaping boulders. The bright, variable emission from the dust produced in large impacts from extreme debris disks provides a unique opportunity to study violent events during the era of terrestrial planet formation.
