- ID:
- ivo://CDS.VizieR/J/ApJ/731/123
- Title:
- APOSTLE light curve of GJ 1214b
- Short Name:
- J/ApJ/731/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three transits of GJ 1214b, observed as part of the Apache Point Observatory Survey of Transit Light Curves of Exoplanets (APOSTLE). By applying Markov Chain Monte Carlo techniques to a multi-wavelength data set which included our r-band light curves and previously gathered data of GJ 1214b, we confirm earlier estimates of system parameters. Using spectral energy distribution fitting, mass-luminosity relations, and light curve data, we derived absolute parameters for the star and planet, improving uncertainties by a factor of two for the stellar mass (M_*_=0.153^+0.010^_-0.009_M_{sun}_), stellar radius (R_*_=0.210^+0.005^_-0.004R_{sun}_), planetary radius (R_p_=2.74^+0.06^_-0.05_R_{earth}_), and planetary density ({rho}_p_=1.68+/-0.23g/cm^3^). Transit times derived from our study show no evidence for strong transit timing variations. We also report the detection of two features in our light curves which we believe are evidence for a low-energy stellar flare and a spot-crossing event.
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- ID:
- ivo://CDS.VizieR/J/ApJ/764/8
- Title:
- APOSTLE r'-band transit lightcurves of TrES-3b
- Short Name:
- J/ApJ/764/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed 11 transits of TrES-3b over two years in order to constrain system parameters and look for transit timing and depth variations. We describe an updated analysis protocol for APOSTLE data, including the reduction pipeline, transit model, and Markov Chain Monte Carlo analyzer. Our estimates of the system parameters for TrES-3b are consistent with previous estimates to within the 2{sigma} confidence level. We improved the errors (by 10%-30%) on system parameters such as the orbital inclination (i_orb_), impact parameter (b), and stellar density ({rho}_{sstarf}_) compared to previous measurements. The near-grazing nature of the system, and incomplete sampling of some transits, limited our ability to place reliable uncertainties on individual transit depths and hence we do not report strong evidence for variability. Our analysis of the transit timing data shows no evidence for transit timing variations and our timing measurements are able to rule out super-Earth and gas giant companions in low-order mean motion resonance with TrES-3b.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/36
- Title:
- APOSTLE transits of XO-2 system
- Short Name:
- J/ApJ/770/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed 10 transits of XO-2b over a period of 3yr. We present measurements that confirm previous estimates of system parameters like the normalized semi-major axis (a/R_*_), stellar density ({rho}_*_), impact parameter (b), and orbital inclination (i_orb_). Our errors on system parameters like a/R_*_ and {rho}_*_ have improved by ~40% compared to previous best ground-based measurements. Our study of the transit times show no evidence for transit timing variations (TTVs) and we are able to rule out co-planar companions with masses >=0.20M_{Earth}_ in low order mean motion resonance with XO-2b. We also explored the stability of the XO-2 system given various orbital configurations of a hypothetical planet near the 2:1 mean motion resonance. We find that a wide range of orbits (including Earth-mass perturbers) are both dynamically stable and produce observable TTVs. We find that up to 51% of our stable simulations show TTVs that are smaller than the typical transit timing errors (~20s) measured for XO-2b, and hence remain undetectable.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/872
- Title:
- A spectropolarimetric analysis of WASP-12
- Short Name:
- J/ApJ/720/872
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The knowledge of accurate stellar parameters is paramount in several fields of stellar astrophysics, particularly in the study of extrasolar planets, where often the star is the only visible component and therefore used to infer the planet's fundamental parameters. Another important aspect of the analysis of planetary systems is the stellar activity and the possible star-planet interaction. Here, we present a self-consistent abundance analysis of the planet-hosting star WASP-12 and a high-precision search for a structured stellar magnetic field on the basis of spectropolarimetric observations obtained with the ESPaDOnS spectropolarimeter. Our results show that the star does not have a structured magnetic field, and that the obtained fundamental parameters are in good agreement with what was previously published. In addition, we derive improved constraints on the stellar age (1.0-2.65Gyr), mass (1.23-1.49M/M_{sun}_), and distance (295-465pc). WASP-12 is an ideal object in which to look for pollution signatures in the stellar atmosphere. We analyze the WASP-12 abundances as a function of the condensation temperature and compare them with those published by several other authors on planet-hosting and non-planet-hosting stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/767/127
- Title:
- Asteroseismic solutions for 77 Kepler stars
- Short Name:
- J/ApJ/767/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used asteroseismology to determine fundamental properties for 66 Kepler planet-candidate host stars, with typical uncertainties of 3% and 7% in radius and mass, respectively. The results include new asteroseismic solutions for four host stars with confirmed planets (Kepler-4, Kepler-14, Kepler-23 and Kepler-25) and increase the total number of Kepler host stars with asteroseismic solutions to 77. A comparison with stellar properties in the planet-candidate catalog by Batalha et al. (2013, J/ApJS/204/24) shows that radii for subgiants and giants obtained from spectroscopic follow-up are systematically too low by up to a factor of 1.5, while the properties for unevolved stars are in good agreement. We furthermore apply asteroseismology to confirm that a large majority of cool main-sequence hosts are indeed dwarfs and not misclassified giants. Using the revised stellar properties, we recalculate the radii for 107 planet candidates in our sample, and comment on candidates for which the radii change from a previously giant-planet/brown-dwarf/stellar regime to a sub-Jupiter size or vice versa. A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters or due to planet candidates that may be in eccentric orbits. Finally, we investigate tentative correlations between host-star masses and planet-candidate radii, orbital periods, and multiplicity, but caution that these results may be influenced by the small sample size and detection biases.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A144
- Title:
- Astrometric observations of Deimos
- Short Name:
- J/A+A/545/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between July 2005 and July 2011 Mars Express performed 50 Deimos approaches. 156 SRC images were acquired and used for astrometric (positional) measurements of the small Martian satellite. For this study, we have developed a new technique, where the center-of-figure of the odd-shaped Deimos was determined by fitting the predicted to the observed satellite limb. The prediction of the limb was made based on the moon's known shape model. The camera pointing was verified and corrected by means of background star observations. We obtained a set of spacecraft- centered Deimos coordinates with accuracies between 0.6 and 3.6km (1 sigma). Comparisons with current orbit models indicate that Deimos is ahead or falling behind its predicted position along its track by as much as +3.7km or -4.4km, respectively, depending on the chosen model. Our data may be used to improve the orbit models of the satellite.
- ID:
- ivo://CDS.VizieR/J/A+AS/143/405
- Title:
- Astrometric observations of Helene
- Short Name:
- J/A+AS/143/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometric photographic positions of the Saturnian satellite Helene obtained from 22 plates taken in 6 nights are presented. The observations are distributed between 5 missions in 1985 and 1987. All positions are compared with those calculated by Jacobson (1999, personal communication). The residuals have mean and standard deviation smaller than 0.25" and 0.30" respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A28
- Title:
- Astrometric observations of Phobos
- Short Name:
- J/A+A/580/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mars Express (MEX) carried out 74 Phobos flybys at distances between 669 and 5579km from April 2008 to August 2011. Images taken with the Super Resolution Channel (SRC) were used to determine the Martian moon's spacecraft-centered right ascension and declination. Image positions of Phobos were measured using the control point and limb fit measurement techniques. Camera pointing and pointing drift were controlled by means of background star observations that were compared to the corresponding positions from the Tycho-2 catalog. Blurred and noisy images were restored by applying an image-based point spread function in a Richardson-Lucy deconvolution. Altogether, we provide 158 astrometric observations of Phobos with estimated uncertainties between 0.224 and 3.405km circular about the direction to the satellite. Control point measurements yield more accurate results than limb fit observations.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A104
- Title:
- Astrometric obs. of Phobos and Deimos in 1971
- Short Name:
- J/A+A/572/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate positional measurements of planets and satellites are used to improve our knowledge of their dynamics and to infer the accuracy of planet and satellite ephemerides. In the framework of the FP7 ESPaCE project, we provide positions of Mars, Phobos and Deimos taken with the U.S. Naval Observatory 26-inch refractor during the 1971 opposition of the planet. These plates were measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process that includes image, instrumental and spherical corrections to provide the most accurate data.
- ID:
- ivo://CDS.VizieR/J/A+A/383/1054
- Title:
- Astrometry of Pluto and Saturn in 1995-2001
- Short Name:
- J/A+A/383/1054
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we publish astrometric positions of Pluto and satellites of Saturn obtained with the Bordeaux and Valinhos CCD meridian circles. These observations are used to test the DE403 and DE405 ephemerides.
