- ID:
- ivo://CDS.VizieR/J/other/SoSyR/52.312
- Title:
- Galilean moons positions
- Short Name:
- J/other/SoSyR/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of the Galilean moons observationals taken with Normal Astrograph of the Pulkovo Observatory in 2016-2017 are presented. 761 positions of the Galilean moons of Jupiter in the system of the Gaia DR1 catalog (ICRF, J2000.0) and 854 differential coordinates of the satellites relative to each other were obtained. The mean errors in the satellites' normal places and the corresponding root-mean-square deviations are (eps)RA=0.0020", (eps)DE=0.0027", (sigm)RA=0.0546", and (sigm)DE=0.0757". The equatorial coordinates of the moons are compared to the motion theories of planets and satellites. On average, the (O-C) residuals in the both coordinates relative to the motion theories are less than 0.031". The best agreement with observations is achieved by a combination of the EPM2015 and V. Lainey-V.2.0|V1.1 motion theories, which yields the average (O-C) residuals of approximately 0.02". Peculiarities in the behavior of the (O-C) residuals and error values in Ganymede have been noticed.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/other/SoSyR/49.383
- Title:
- Galilean satellites & Jupiter positions
- Short Name:
- J/other/SoSyR/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For observational period of 2009-2011 we have obtained 140 positions of Galilean satellites and 42 calculated positions of Jupiter in the system of UCAC4 catalogue (ICRS, J2000.0). Accuracy estimation gives error of mean position as 0.02-0.04". The resulting equatorial coordinates satellites were compared with the eight contemporary theories of the motion of planets and satellites. On average, the (O-C) residuals in both coordinates do not exceed 0.08" relative to all theories of motion. Comparison of the calculated equatorial coordinates of Jupiter (were obtained from observations of galilean satellites) with the INPOP10 theory of planetary motion has shown satisfactory results. The average deviations were obtained respectively (O-C)RA=0.040" and (O-C)DE=-0.053". This work was supported by the Program 22 of the Presidium of RAS and RFBR grant (12-02-00675-a).
- ID:
- ivo://CDS.VizieR/J/A+A/532/A36
- Title:
- Galilean satellites mutual events in 2009
- Short Name:
- J/A+A/532/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry of mutual events between natural satellites has been verified to be a most effective and accurate ground-based method for obtaining accurate astrometric data through fitting the light curves observed during these events, and it will be valuable to develop the orbital models of the natural satellites. Mutual occultations of J2 Europa by J1 Io (Aug 28, 2009), J1 Io by J2 Europa (Nov 9 and Dec 11, 2009) and J1 Io by J3 Ganymede (Nov 28, 2009) were observed at Yunnan Observatory during the PHEMU09 international campaign. We will calculate the astrometric data of satellites by analyzing and fitting the light curves we got. The same model proposed by N.V. Emelianov (2003SoSyR..37..314E) was used to fit the light curves, with the Lommel-Seeliger scattering law taking into account. Dynamical quantities, such as the deviation of the observed relative satellite motion from the theoretical motion provided by the relevant ephemeris denoted as Dx and Dy, impact parameter and mid-time corresponding to the impact parameter, were obtained for each event respectively. These results have an accuracy of about several mas to 90mas for Dx and Dy and 0.31-2.97s for mid-time. The residuals in determination of longitude shifts (delta(l1) for J1 Io and delta(l2) for J2 Europa) explaining the shifts of the mid-times of the events, were also calculated in the section of discussion which is around 10km with the best ephemerides.
- ID:
- ivo://CDS.VizieR/J/ApJ/881/1
- Title:
- Global energetics of solar flares. VIII.
- Short Name:
- J/ApJ/881/1
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- One of the key problems in solar flare physics is the determination of the low-energy cut-off: the value that determines the energy of nonthermal electrons and hence flare energetics. We discuss different approaches to determine the low-energy cut-off in the spectrum of accelerated electrons: (I) the total electron number model, (II) the time-of-flight model (based on the equivalence of the time-of-flight and the collisional deflection time), (III) the warm target model of Kontar et al., and (IV) the model of the spectral cross-over between thermal and nonthermal components. We find that the first three models are consistent with a low-energy cutoff with a mean value of ~10keV, while the cross-over model provides an upper limit for the low-energy cutoff with a mean value of ~21keV. Combining the first three models we find that the ratio of the nonthermal energy to the dissipated magnetic energy in solar flares has a mean value of qE=0.57{+/-}0.08, which is consistent with an earlier study based on the simplified approximation of the warm target model alone (qE=0.51{+/-}0.17). This study corroborates the self-consistency between three different low-energy cutoff models in the calculation of nonthermal flare energies.
- ID:
- ivo://CDS.VizieR/J/AJ/160/277
- Title:
- gri-light curve of near-Earth asteroid 2020 CD3
- Short Name:
- J/AJ/160/277
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We report on our detailed characterization of Earth's second known temporary natural satellite, or minimoon, asteroid 2020CD3. An artificial origin can be ruled out based on its area-to-mass ratio and broadband photometry, which suggest that it is a silicate asteroid belonging to the S or V complex in asteroid taxonomy. The discovery of 2020CD3 allows for the first time a comparison between known minimoons and theoretical models of their expected physical and dynamical properties. The estimated diameter of 1.2_-0.2_^+0.4^m and geocentric capture approximately a decade after the first known minimoon, 2006RH120, are in agreement with theoretical predictions. The capture duration of 2020CD3 of at least 2.7yr is unexpectedly long compared to the simulation average, but it is in agreement with simulated minimoons that have close lunar encounters, providing additional support for the orbital models. 2020CD3's atypical rotation period, significantly longer than theoretical predictions, suggests that our understanding of meter-scale asteroids needs revision. More discoveries and a detailed characterization of the population can be expected with the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A99
- Title:
- Helioseismic measurements of solar meridional flow
- Short Name:
- J/A+A/619/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The solar meridional flow is an essential ingredient in flux-transport dynamo models. However, no consensus on its subsurface structure has been reached. We merge the data sets from SOHO/MDI and SDO/HMI with the aim of achieving a greater precision on helioseismic measurements of the subsurface meridional flow. The south-north travel-time differences are measured by applying time-distance helioseismology to the MDI and HMI medium-degree Dopplergrams covering May 1996-April 2017. Our data analysis corrects for several sources of systematic effects: P-angle error, surface magnetic field effects, and center-to-limb variations. For HMI data, we used the P-angle correction provided by the HMI team based on the Venus and Mercury transits. For MDI data, we used a P-angle correction estimated from the correlation of MDI and HMI data during the period of overlap. The center-to-limb effect is estimated from the east-west travel-time differences and is different for MDI and HMI observations. An interpretation of the travel-time measurements is obtained using a forward-modeling approach in the ray approximation. In the latitude range 20{deg}-35{deg}, the travel-time differences are similar in the southern hemisphere for cycles 23 and 24. However, they differ in the northern hemisphere between cycles 23 and 24. Except for cycle 24's northern hemisphere, the measurements favor a single-cell meridional circulation model where the poleward flows persist down to ~0.8R_{sun}_, accompanied by local inflows toward the activity belts in the near-surface layers. Cycle 24's northern hemisphere is anomalous: travel-time differences are significantly smaller when travel distances are greater than 20{deg}. This asymmetry between northern and southern hemispheres during cycle 24 was not present in previous measurements, which assumed a different P-angle error correction where south-north travel-time differences are shifted to zero at the equator for all travel distances. In our measurements, the travel-time differences at the equator are zero for travel distances less than ~30{deg}, but they do not vanish for larger travel distances. This equatorial offset for large travel distances need not be interpreted as a deep cross-equator flow; it could be due to the presence of asymmetrical local flows at the surface near the end points of the acoustic ray paths. The combined MDI and HMI helioseismic measurements presented here contain a wealth of information about the subsurface structure and the temporal evolution of the meridional circulation over 21 years. To infer the deep meridional flow, it will be necessary to model the contribution from the complex time-varying flows in the near-surface layers.
- ID:
- ivo://archive.stsci.edu/hut
- Title:
- Hopkins Ultraviolet Telescope
- Short Name:
- HUT
- Date:
- 22 Jul 2020 21:30:05
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- The Hopkins Ultraviolet Telescope (HUT) was a shuttle-borne instrument used to obtain ultraviolet spectra in the far ultraviolet region of the spectrum. It was part of the ASTRO payload complement of three co-mounted instruments that flew in December 1990 and March 1995 as Space Shuttle missions. More than 650 spectra were obtained of 340 targets. In April, 2013, the HUT data was reprocessed to improve calibration, expand metadata, add new data products, and update file formats. The current cone service uses the metadata from these reprocessed files.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A53
- Title:
- Horizontal temperature at Venus upper atmosphere
- Short Name:
- J/A+A/585/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we analysed nadir observations of atmospheric infrared emissions carried out by VIRTIS, a high-resolution spectrometer on board the European spacecraft Venus Express. We focused on the ro-vibrational band of CO2 at 4.3 microns on the dayside, whose fluorescence originates in the Venus upper mesosphere and above. This is the first time that a systematic sounding of these non-local thermodynamic equilibrium (NLTE) emissions has been carried out in Venus using this geometry. As many as 143,218 spectra have been analysed on the dayside during the period 14/05/2006 to 14/09/2009. We designed an inversion method to obtain the atmospheric temperature from these non-thermal observations, including a NLTE line-by-line forward model and a pre-computed set of spectra for a set of thermal structures and illumination conditions. Our measurements sound a broad region of the upper mesosphere and lower thermosphere of Venus ranging from 10^-2^ to 10^-5^mb (which in the Venus International Reference Atmosphere, VIRA, is approximately 100-150km during the daytime) and show a maximum around 195+/-10K in the subsolar region, decreasing with latitude and local time towards the terminator. This is in qualitative agreement with predictions by a Venus Thermospheric General Circulation Model (VTGCM) after a proper averaging of altitudes for meaningful comparisons, although our temperatures are colder than the model by about 25K throughout. We estimate a thermal gradient of about 35K between the subsolar and antisolar points when comparing r data with nightside temperatures measured at similar altitudes by SPICAV, another instrument on Venus Express (VEx). Our data show a stable temperature structure through five years of measurements, but we also found episodes of strong heating/cooling to occur in the subsolar region of less than two days.
- ID:
- ivo://CDS.VizieR/J/AJ/152/195
- Title:
- HST and Magellan observations of Haumea system
- Short Name:
- J/AJ/152/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hi'iaka is the larger outer satellite of the dwarf planet Haumea. Using relative photometry from the Hubble Space Telescope and Magellan and a phase dispersion minimization analysis, we have identified the rotation period of Hi'iaka to be ~9.8hr (double peaked). This is ~120 times faster than its orbital period, creating new questions about the formation of this system and possible tidal evolution. The rapid rotation suggests that Hi'iaka could have a significant obliquity and spin precession that could be visible in light curves within a few years. We then turn to an investigation of what we learn about the (currently unclear) formation of the Haumea system and family based on this unexpectedly rapid rotation rate. We explore the importance of the initial semimajor axis and rotation period in tidal evolution theory and find that they strongly influence the time required to despin to synchronous rotation, relevant to understanding a wide variety of satellite and binary systems. We find that despinning tides do not necessarily lead to synchronous spin periods for Hi'iaka, even if it formed near the Roche limit. Therefore, the short rotation period of Hi'iaka does not rule out significant tidal evolution. Hi'iaka's spin period is also consistent with formation near its current location and spin-up due to Haumea-centric impactors.
- ID:
- ivo://vopdc.obspm/imcce
- Title:
- IMCCE VO Solar System Portal
- Short Name:
- VO-IMCCE
- Date:
- 10 Jan 2017
- Publisher:
- Paris Astronomical Data Centre - IMCCE
- Description:
- The IMCCE is a research institute of the Paris Observatory, associated with the CNRS (UMR8028), whose work concerns mainly the dynamic and planetologic studies of the bodies of the solar system and of the terrestrial environment: planets, natural satellites, asteroids, comets, meteoroids and space debris. The IMCCE, through its VO Solar System Portal, places at the disposal of the Virtual observatory its knowledge and its expertise which concern the dynamics and the physics of the bodies of the solar system through databases, ephemeris computation services, tools of simulation, and numerical computation services fully compliant with the interoperability concept of the Virtual Observatory.
