- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2734
- Title:
- Planet-hosting solar-type stars magnetic fields
- Short Name:
- J/MNRAS/465/2734
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectropolarimetric snapshot survey of solar-type planet-hosting stars. In addition to 14 planet-hosting stars observed as part of the BCool magnetic snapshot survey, we obtained magnetic observations of a further 19 planet-hosting solar-type stars in order to see if the presence of close-in planets had an effect on the measured surface magnetic field (|B_l_|). Our results indicate that the magnetic activity of this sample is congruent with that of the overall BCool sample. The effects of the planetary systems on the magnetic activity of the parent star, if any, are too subtle to detect compared to the intrinsic dispersion and correlations with rotation, age and stellar activity proxies in our sample. Four of the 19 newly observed stars, two of which are subgiants, have unambiguously detected magnetic fields and are future targets for Zeeman-Doppler mapping.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/544/A106
- Title:
- p-mode frequencies of the solar twin 18 Sco
- Short Name:
- J/A+A/544/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Solar twins have been a focus of attention for more than a decade, because their structure is extremely close to that of the Sun. Today, thanks to high-precision spectrometers, it is possible to use asteroseismology to probe their interiors. Our goal is to use time series obtained from the HARPS spectrometer to extract the oscillation frequencies of 18 Sco, the brightest solar twin. We used the tools of spectral analysis to estimate these quantities. We estimate 52 frequencies using a Markov Chain Monte-Carlo (MCMC) algorithm. After examination of their probability densities and comparison with results from direct MAP optimization, we obtain a minimal set of 21 reliable modes. The identification of each pulsation mode is straightforwardly accomplished by comparing to the well-established solar pulsation modes. We also derived some basic seismic indicators using these values. These results offer a good basis to start a detailed seismic analysis of 18 Sco using stellar models.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A34
- Title:
- Pulsating solar-like stars in Kepler
- Short Name:
- J/A+A/572/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have independently measured asteroseismic ages, measurements of rotation and activity are particularly interesting in the context of age-rotation-activity relations. In particular, age-rotation relations generally lack good calibrators at old ages, a problem that this Kepler sample of old-field stars is uniquely suited to address. We study the surface rotation and photometric magnetic activity of a subset of 540 solar-like stars on the main-sequence and the subgiant branch for which stellar pulsations have been measured.
- 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/154/181
- 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/ApJ/708/1366
- Title:
- Radial velocities for 61 Vir
- Short Name:
- J/ApJ/708/1366
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present precision radial velocity data that reveal a multiple exoplanet system orbiting the bright nearby G5V star 61 Virginis. Our 4.6 years of combined Keck/HIRES and Anglo-Australian Telescope precision radial velocities indicate the hitherto unknown presence of at least three planets orbiting this well-studied star. These planets are all on low-eccentricity orbits with periods of 4.2, 38.0, and 124.0 days, and projected masses (Msini) of 5.1, 18.2, and 24.0M_{earth}_, respectively. Test integrations of systems consistent with the radial velocity data suggest that the configuration is dynamically stable.
- ID:
- ivo://CDS.VizieR/J/AJ/161/106
- Title:
- Radial velocities of 12 Psc and HD 159062
- Short Name:
- J/AJ/161/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of a white dwarf companion to the G1 V star 12Psc found as part of a Keck adaptive optics imaging survey of long-term accelerating stars from the McDonald Observatory Planet Search Program. Twenty years of precise radial-velocity monitoring of 12Psc with the Tull Spectrograph at the Harlan J. Smith telescope reveals a moderate radial acceleration (~10m/s/yr), which together with relative astrometry from Keck/NIRC2 and the astrometric acceleration between Hipparcos and Gaia DR2 yields a dynamical mass of M_B_=0.605_-0.022_^+0.021^M{sun} for 12PscB, a semimajor axis of 40_-4_^+2^au, and an eccentricity of 0.84{+/-}0.08. We also report an updated orbital fit of the white dwarf companion to the metal-poor (but barium-rich) G9 V dwarf HD159062 based on new radial velocity observations from the High-Resolution Spectrograph at the Hobby-Eberly Telescope and astrometry from Keck/NIRC2. A joint fit of the available relative astrometry, radial velocities, and tangential astrometric acceleration yields a dynamical mass of M_B_=0.609_-0.011_^+0.010^M{sun} for HD159062B, a semimajor axis of 60_-7_^+5^au, and preference for circular orbits (e<0.42 at 95% confidence). 12PscB and HD159062B join a small list of resolved Sirius-like benchmark white dwarfs with precise dynamical mass measurements which serve as valuable tests of white dwarf mass-radius cooling models and probes of AGB wind accretion onto their main-sequence companions.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A159
- Title:
- Radial velocity measurements of 51 Peg
- Short Name:
- J/A+A/646/A159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of exoplanetary atmospheres by means of high-resolution spectroscopy is an expanding research field which provides information o n chemical composition, thermal structure, atmospheric dynamics and orbital velocity of exoplanets. In this work, we aim at the detection of the light reflected by the exoplanet 51 Peg b employing optical high-resolution spectroscopy. To detect the light reflected by the planetary dayside we use optical HARPS and HARPS-N spectra taken near the superior conjunction of the planet, when the flux contrast between the planet and the star is maximum. To search for the weak planetary signal, we cross-correlate the observed spectra with a high S/N stellar spectrum. We homogeneously analyze the available datasets and derive a 10^-5^ upper limit on the planet-to-star flux contrast in the optical. The upper limit on the planet-to-star flux contrast of 10^-5^ translates into a low albedo of the planetary atmosphere (A_g_~0.05-0.15 for an assumed planetary radius in the range 1.5-0.9R_Jup_, as estimated from the planet's mass).
- ID:
- ivo://CDS.VizieR/J/A+A/634/L9
- Title:
- Rotation periods of 97 solar-like stars
- Short Name:
- J/A+A/634/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The accurate determination of stellar rotation periods is important for estimating stellar ages and for understanding stellar activity and evolution. While rotation periods can be determined for about thirty thousand stars in the Kepler field, there are over one hundred thousand stars, especially with low photometric variability and irregular pattern of variations, for which rotational periods are unknown. Here we investigate the effect of metallicity on the detectability of rotation periods. This is done by synthesising light curves of hypothetical stars that are identical to our Sun with the exception of the metallicity. These light curves are then used as an input to the period determination algorithms. We find that the success rate for recovering the rotation signal has a minimum close to the solar metallicity value. This can be explained by the compensation effect of facular and spot contributions. In addition, selecting solar-like stars with near-solar effective temperature and photometric variability, and with metallicity between M/H=-0.35 and M/H=0.35 from the Kepler sample, we analyse the fraction of stars for which rotational periods have been detected as a function of metallicity. In agreement with our theoretical estimate we find a local minimum for the detection fraction close to the solar metallicity. We further report rotation periods of 87 solar-like Kepler stars for the first time.
- ID:
- ivo://CDS.VizieR/J/AJ/159/44
- Title:
- RV curve of the metal-rich exoplanet host star XO-7
- Short Name:
- J/AJ/159/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transiting planets orbiting bright stars are the most favorable targets for follow-up and characterization. We report the discovery of the transiting hot Jupiter XO-7b and of a second, massive companion on a wide orbit around a circumpolar, bright, and metal-rich G0 dwarf (V=10.52, T_eff_=6250{+/-}100K, [Fe/H]=0.432{+/-}0.057dex). We conducted photometric and radial velocity follow-up with a team of amateur and professional astronomers. XO-7b has a period of 2.8641424{+/-}0.0000043days, a mass of 0.709{+/-}0.034M_J_, a radius of 1.373{+/-}0.026R_J_, a density of 0.340{+/-}0.027g/cm^3^, and an equilibrium temperature of 1743{+/-}23K. Its large atmospheric scale height and the brightness of the host star make it well suited to atmospheric characterization. The wide-orbit companion is detected as a linear trend in radial velocities with an amplitude of ~100m/s over two years, yielding a minimum mass of 4M_J_; it could be a planet, a brown dwarf, or a low-mass star. The hot Jupiter orbital parameters and the presence of the wide-orbit companion point toward a high-eccentricity migration for the hot Jupiter. Overall, this system will be valuable to understand the atmospheric properties and migration mechanisms of hot Jupiters and will help constrain the formation and evolution models of gas giant exoplanets.
