- 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.
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- 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).
- ID:
- ivo://CDS.VizieR/J/AJ/154/196
- Title:
- Properties of comet 49P/Arend-Rigaux, 1984-2012
- Short Name:
- J/AJ/154/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed images of comet 49P/Arend-Rigaux on 33 nights between 2012 January and May and obtained R-band lightcurves of the nucleus. Through usual phasing of the data, we found a double-peaked lightcurve having a synodic rotation period of 13.450+/-0.005 hr. Similarly, phase dispersion minimization and the Lomb-Scargle method both revealed rotation periods of 13.452 hr. Throughout the 2011/2012 apparition, the rotation period was found to increase by a small amount, consistent with a retrograde rotation of the nucleus. We also reanalyzed the publicly available data from the 1984/1985 apparition by applying the same techniques, finding a rotation period of 13.45+/-0.01 hr. Based on these findings, we show that the change in rotation period is less than 14 s per apparition. Furthermore, the amplitudes of the lightcurves from the two apparitions are comparable, to within reasonable errors, even though the viewing geometries differ, implying that we are seeing the comet at a similar sub-Earth latitude. We detected the presence of a short-term jet-like feature in 2012 March, which appears to have been created by a short-duration burst of activity on March 15. Production rates obtained in 2004/2005, along with reanalysis of the previous results from 1984/1985, imply a strong seasonal effect and a very steep fall-off after perihelion. This, in turn, implies that a single source region, rather than leakage from the entire nucleus, dominates activity.
140. (16) Psyche images
- ID:
- ivo://CDS.VizieR/J/A+A/619/L3
- Title:
- (16) Psyche images
- Short Name:
- J/A+A/619/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be related to iron meteorites. Such an association is however challenged by both its near- and mid-infrared spectral properties and the reported estimates of its density. Here, we aim to refine the density of (16) Psyche to set further constraints on its bulk composition and determine its potential meteoritic analog. We observed (16) Psyche with ESO VLT/SPHERE/ZIMPOL as part of our large program (ID 199.C-0074). We used the high angular resolution of these observations to refine Psyche's three-dimensional (3D) shape model and subsequently its density when combined with the most recent mass estimates. In addition, we searched for potential companions around the asteroid. We derived a bulk density of 3.99+/-0.26g/cm^3^ for Psyche. While such density is incompatible at the 3-sigma level with any iron meteorites (~7.8g/cm^3^), it appears fully consistent with that of stony-iron meteorites such as mesosiderites (density ~4.25g/cm^3^). In addition, we found no satellite in our images and set an upper limit on the diameter of any non-detected satellite of 1460+/-200m at 150km from Psyche (0.2%xR_Hill_, the Hill radius) and 800+/-200m at 2000km (3%xRHill). Considering that the visible and near-infrared spectral properties of mesosiderites are similar to those of Psyche, there is merit to a long-published initial hypothesis that Psyche could be a plausible candidate parent body for mesosiderites.
