- ID:
- ivo://CDS.VizieR/J/A+A/639/A88
- Title:
- Plage area composite series
- Short Name:
- J/A+A/639/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of long-term solar activity and variability require knowledge of the past evolution of the solar surface magnetism. An important source of such information are the archives of full-disc CaII K observations performed more or less regularly at various sites since 1892. We derive the plage area evolution over the last 12 solar cycles employing data from all CaII K archives available publicly in digital form known to us, including several as yet unexplored CaII K archives. We analyse more than 290000 full-disc CaII K observations from 43 datasets spanning the period 1892-2019. All images were consistently processed with an automatic procedure that performs the photometric calibration (if needed) and the limb-darkening compensation. The processing also accounts for artefacts plaguing many of the images, including some very specific artefacts such as bright arcs found in Kyoto and Yerkes data. The employed methods have previously been tested and evaluated on synthetic data and found to be more accurate than other methods used in the literature to treat a subset of the data analysed here. We have produced a plage area time-series from each analysed dataset. We found that the differences between the plage areas derived from individual archives are mainly due to the differences in the central wavelength and the bandpass used to acquire the data at the various sites. We have empirically cross-calibrated and combined the results obtained from each dataset to produce a composite series of plage areas. "Backbone" series are used to bridge all the series together. We have also shown that the selection of the backbone series has little effect on the final plage area composite. We have quantified the uncertainty of determining the plage areas with our processing due to shifts in the central wavelength and found it to be less than 0.01 in fraction of the solar disc for the average conditions found on historical data. We also found the variable seeing conditions during the observations to slightly increase the plage areas during activity maxima. We provide the so far most complete time series of plage areas based on corrected and calibrated historical and modern CaII K images. Consistent plage areas are now available on 88% of all days from 1892 onwards and on 98% from 1907 onwards.
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- ID:
- ivo://CDS.VizieR/J/A+A/605/A72
- Title:
- Planetary systems AMD-stability
- Short Name:
- J/A+A/605/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here in full detail the evolution of the angular momentum deficit (AMD) during collisions as it was described in (Laskar 2000, Physical Review Letters, 84, 3240). Since then, the AMD has been revealed to be a key parameter for the understanding of the outcome of planetary formation models. We define here the AMD-stability criterion that can be easily verified on a newly discovered planetary system. We show how AMD-stability can be used to establish a classification of the multiplanet systems in order to exhibit the planetary systems that are long-term stable because they are AMD-stable, and those that are AMD- unstable which then require some additional dynamical studies to conclude on their stability. The AMD-stability classification is applied to the 131 multiplanet systems from The Extrasolar Planet Encyclopaedia database (exoplanet.eu) for which the orbital elements are sufficiently well known.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/L4
- Title:
- Polar network index for the solar cycle studies
- Short Name:
- J/ApJ/793/L4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sun has a polar magnetic field which oscillates with the 11 yr sunspot cycle. This polar magnetic field is an important component of the dynamo process which operates in the solar convection zone and produces the sunspot cycle. We have direct systematic measurements of the Sun's polar magnetic field only from about the mid-1970s. There are, however, indirect proxies which give us information about this field at earlier times. The Ca-K spectroheliograms taken at the Kodaikanal Solar Observatory during 1904-2007 have now been digitized with 4kx4k CCD and have higher resolution (~0.86 arcsec) than the other available historical data sets. From these Ca-K spectroheliograms, we have developed a completely new proxy (polar network index, hereafter PNI) for the Sun's polar magnetic field. We calculate PNI from the digitized images using an automated algorithm and calibrate our measured PNI against the polar field as measured by the Wilcox Solar Observatory for the period 1976-1990. This calibration allows us to estimate the polar fields for the earlier period up to 1904. The dynamo calculations performed with this proxy as input data reproduce reasonably well the Sun's magnetic behavior for the past century.
- ID:
- ivo://CDS.VizieR/J/A+AS/107/559
- Title:
- Position of Uranian satellites
- Short Name:
- J/A+AS/107/559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/454/683
- Title:
- Position of Uranian satellites
- Short Name:
- J/A+A/454/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Puck, a faint satellite very close to Uranus' planet, was discovered by Voyager 2 Spacecraft images in 1986. Ever since then, few observations from Earth have been made. This prompted us to start a program of systematic observations of this satellite with the 1.6m telescope at the Laboratorio Nacional de Astrofisica/MCT (Itajuba, Brazil). The success of the observations is mainly due to the use of a Coronagraph developed at Observatorio Nacional/MCT (Rio de Janeiro, Brazil). This article presents astrometric positions obtained from Earth observations of Puck and of the five major Uranian satellites for four nights in 2004. Those positions are compared to the theoretically calculated positions from JPL Development Ephemeris. For Puck, the root mean square (rms) of the mean residual was found to be 84 milliarcseconds (mas). The stars' USNO-A2.0 catalog (<I/252>) was used as a reference system for the astrometric calibration.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A76
- Title:
- Positions of satellites of giant planets
- Short Name:
- J/A+A/580/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The irregular satellites of the giant planets are believed to have been captured during the evolution of the solar system. Knowing their physical parameters, such as size, density and albedo is important to constrain where they came from and how they were captured. The best way to obtain these parameters are observations in situ by spacecrafts or from stellar occultations by the objects. Both techniques demand that the orbits are well known. We aimed to obtain good astrometric positions of irregular satellites in order to improve their orbits and ephemeris. We identified and reduced observations of several irregular satellites from three databases containing more than 8000 images obtained between 1992 and 2014 at three sites (Observatorio do Pico dos Dias, Observatoire de Haute-Provence and European Southern Observatory - La Silla). We used the software PRAIA (Platform for Reduction of Astronomical Images Automatically) to make the astrometric reduction of the CCD frames. The UCAC4 catalogue represented the International Celestial Reference System in the reductions. The identification of the satellites in the frames was done through their ephemerides as determined from the SPICE/NAIF kernels. Some procedures were taken to overcome missing or incomplete information (coordinates, date), mostly for the older images. We managed to obtain more than 6000 positions for 18 irregular satellites, being 12 of Jupiter, 4 of Saturn, 1 of Uranus (Sycorax) and 1 of Neptune (Nereid). For some satellites the number of obtained positions is more than 50% of that used in earlier orbital numerical integrations. Comparison of our positions with recent JPL ephemeris suggests the presence of systematic errors in the orbits for some of the irregular satellites. The most evident case was an error in the inclination of Carme.
- ID:
- ivo://CDS.VizieR/J/AJ/161/237
- Title:
- Positions of Triton with Sheshan Station telescope
- Short Name:
- J/AJ/161/237
- Date:
- 20 Jan 2022
- Publisher:
- CDS
- Description:
- The large time span and precise observational data of natural satellites is of great significance for updating their ephemerides and studying their dynamic characteristics. With the help of the new image-processing methods and the Gaia DR2 catalog, all CCD images of Triton taken with the 1.56m telescope of Shanghai Astronomical Observatory during 2005-2009 were reanalyzed. The median filtering algorithm is used for image preprocessing to remove the influence of the halo of Neptune, and an upgraded modified moment, called the intensity-square-weighted centroiding method, is applied to determine the centroids of the stars and Triton. A total of 2299 positions of Triton were obtained, including 263 new observed positions and 2036 updated observed positions. Such five-year time span data with high precision will be very helpful to improve the orbit parameters of Triton.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/1117
- Title:
- Possible Ceres asteroid paleo-family
- Short Name:
- J/MNRAS/458/1117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ceres is the largest and most massive body in the asteroid main belt. Observational data from the Dawn spacecraft reveal the presence of at least two impact craters about 280km in diameter on the Ceres surface, that could have expelled a significant number of fragments. Yet, standard techniques for identifying dynamical asteroid families have not detected any Ceres family. In this work, we argue that linear secular resonances with Ceres deplete the population of objects near Ceres. Also, because of the high escape velocity from Ceres, family members are expected to be very dispersed, with a considerable fraction of km-sized fragments that should be able to reach the pristine region of the main belt, the area between the 5J:-2A and 7J:-3A mean-motion resonances, where the observed number of asteroids is low. Rather than looking for possible Ceres family members near Ceres, here we propose to search in the pristine region.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/2638
- Title:
- Precise CCD positions of Phoebe in 2011-2014
- Short Name:
- J/MNRAS/449/2638
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 346 new CCD observations during the years 2011-2014 have been reduced to derive the precise positions of Phoebe, the ninth satellite of Saturn. The observations were made by the 2.4 m telescope at Yunnan Observatory over nine nights. Due to the use of a focal-reducer on the telescope, its significant geometric distortion is solved for and removed for each CCD field of view. The positions of Phoebe are measured with respect to the stars in UCAC2 catalogue (Cat. I/289). The theoretical position of Phoebe was retrieved from the Institute de Mechanique Celeste et de Calcul des Ephemerides (IMCCE) ephemeris which includes the latest theory PH12 by Desmars et al. (2013, J/A+A/553/A36), while the position of Saturn was obtained from the Jet Propulsion Laboratory ephemeris DE431. Our results show that the mean O-Cs (observed minus computed) are -0.02 and -0.07 arcsec in right ascension and declination, respectively. The dispersions of our observations are estimated at about 0.04 arcsec in each direction.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/179
- Title:
- Precision meteor orbits
- Short Name:
- J/A+AS/128/179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orbital elements, encounter data and other relevant information of 359 photographic meteors (Table 2 of the paper).
