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11. Cassini ISS astrometry of Saturnian satellites
ID:
ivo://CDS.VizieR/J/AJ/149/27
Title:
Cassini ISS astrometry of Saturnian satellites
Short Name:
J/AJ/149/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present numerically derived orbits and mass estimates for the inner Saturnian satellites, Atlas, Prometheus, Pandora, Janus, and Epimetheus from a fit to 2580 new Cassini Imaging Science Subsystem astrometric observations spanning 2004 February to 2013 August. The observations are provided as machine-readable and Virtual Observatory tables. We estimate GM_Atlas_=(0.384+/-0.001)x10^-3^km^3^/s^2^, a value 13% smaller than the previously published estimate but with an order of magnitude reduction in the uncertainty. We also find GM_Prometheus_=(10.677+/-0.006)x10^-3^km^3^/s^2^, GM_Pandora_=(9.133+/-0.009)x10^-3^km^3^/s^2^, GM_Janus_=(126.51+/-0.03)x10^-3^km^3^/s^2^, and GM_Epimetheus_=(35.110+/-0.009)x10^-3^km^3^/s^2^, consistent with previously published values, but also with significant reductions in uncertainties. We show that Atlas is currently librating in both the 54:53 co-rotation-eccentricity resonance (CER) and the 54:53 inner Lindblad (ILR) resonance with Prometheus, making it the latest example of a coupled CER-ILR system, in common with the Saturnian satellites Anthe, Aegaeon, and Methone, and possibly Neptune's ring arcs. We further demonstrate that Atlas's orbit is chaotic, with a Lyapunov time of ~10years, and show that its chaotic behavior is a direct consequence of the coupled resonant interaction with Prometheus, rather than being an indirect effect of the known chaotic interaction between Prometheus and Pandora. We provide an updated analysis of the second-order resonant perturbations involving Prometheus, Pandora, and Epimetheus based on the new observations, showing that these resonant arguments are librating only when Epimetheus is the innermost of the co-orbital pair, Janus and Epimetheus. We also find evidence that the known chaotic changes in the orbits of Prometheus and Pandora are not confined to times of apse anti-alignment.
12. Catalogs of potential detections of asteroids
ID:
ivo://CDS.VizieR/J/A+A/659/A38
Title:
Catalogs of potential detections of asteroids
Short Name:
J/A+A/659/A38
Date:
02 Mar 2022 07:50:46
Publisher:
CDS
Description:
The store of data collected in public astronomical archives across the world is continuously expanding and, thus, providing a convenient interface for accessing this information is a major concern for ensuring a second life for the data. In this context, Solar System objects (SSOs) are often difficult or even impossible to query, owing to their ever-changing sky coordinates. Our study is aimed at providing the scientific community with a search service for all potential detections of SSOs among the ESA astronomy archival imaging data, called the Solar System Object Search Service (SSOSS). We illustrate its functionalities using the case of asteroid (16) Psyche, for which no information in the far-IR (70-500 $\mu$m) has previously been reported, to derive its thermal properties in preparation for the upcoming NASA Psyche mission. We performed a geometrical cross-match of the orbital path of each object, as seen by the satellite reference frame, with respect to the public high-level imaging footprints stored in the ESA archives. There are about 800000 asteroids and 2000 comets included in the SSOSS, available through ESASky, providing both targeted and serendipitous observations. For this first release, three missions were chosen: XMM-Newton, the Hubble Space Telescope (HST), and Herschel Observatory. We present a catalog listing all potential detections of asteroids within estimated limiting magnitude or flux limit in Herschel, XMM-Newton, and HST archival imaging data, including 909 serendipitous detections in Herschel images, 985 in XMM-Newton Optical Monitor camera images, and over 32000 potential serendipitous detections in HST images. We also present a case study: the analysis of the thermal properties of Psyche from four serendipitous Herschel detections, combined with previously published thermal IR measurements. We see strong evidence for an unusual drop in (hemispherical spectral) emissivity, from 0.9 at 100um down to about 0.6 at 350um, followed by a possible but not well-constrained increase towards 500um, comparable to what was found for Vesta. The combined thermal data set puts a strong constraint on Psyche's thermal inertia (between 20 to 80J/m^2^/s^1/2^/K) and favors an intermediate to low level surface roughness (below 0.4 for the rms of surface slopes). Conclusions: Using the example of Psyche, we show how the SSOSS provides fast access to observations of SSOs from the ESA astronomical archives, regardless of whether the particular object was the actual target. This greatly simplifies the task of searching, identifying, and retrieving such data for scientific analysis.
13. CCD observations of Phoebe in 1998-1999
ID:
ivo://CDS.VizieR/J/A+A/391/767
Title:
CCD observations of Phoebe in 1998-1999
Short Name:
J/A+A/391/767
Date:
21 Oct 2021
Publisher:
CDS
Description:
In 1998 and 1999, we started observations of the 9th satellite of Saturn. We made 163 observations using the 120cm-telescope of Observatoire de Haute-Provence, France. We used the USNO A2 catalogue (Cat. <I/252>) of stars for the astrometric reduction. With the help of observations of optical counterparts of ICRF sources, a zonal correction to the USNO A2.0 catalogue was computed and applied to the Phoebe positions. A comparison to the most recent theories was made.
14. CCD observations of saturnian satellites
ID:
ivo://CDS.VizieR/J/other/SoSyR/45.523
Title:
CCD observations of saturnian satellites
Short Name:
J/other/SoSyR/45
Date:
21 Oct 2021
Publisher:
CDS
Description:
The astrometric positions of seven saturnian satellites are presented. Positions were derived from more then 5000 CCD frames taken with 26-inch Zeiss refractor at Pulkovo from Jan 2008 to may 2009. Astrometric reduction algorithm is based on Turner's method with using UCAC2 catalog as reference one. Observed positions were compared with theoretical ones from TASS 1.7 (Viennel & Duriez, 1995A&A...297..588V). The accuracy is about 0.05 arcsec. Also positions of Saturn were obtained from observations of satellites 2-6.
15. CCD positions for eight Jovian irregular satellites
ID:
ivo://CDS.VizieR/J/A+A/453/349
Title:
CCD positions for eight Jovian irregular satellites
Short Name:
J/A+A/453/349
Date:
21 Oct 2021
Publisher:
CDS
Description:
The astrometric positions of eight irregular Jovian satellites are given for the oppositions of the planet from 1995 to 1999. These positions were measured on 204 CCD frames obtained at the Cassegrain focus of a 1.6m reflector. They are compared with the theoretically calculated positions from JPL Development Ephemeris. The observed minus-calculated standard deviation for all observations of the eight satellites are {sigma}_RA_=0.071" and {sigma}_DE_=0.052". The USNO-A2.0 (<I/252>) catalog was used for the astrometric calibration.
16. Close encounters to the Sun in Gaia DR1
ID:
ivo://CDS.VizieR/J/A+A/609/A8
Title:
Close encounters to the Sun in Gaia DR1
Short Name:
J/A+A/609/A8
Date:
21 Oct 2021
Publisher:
CDS
Description:
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which pass within a few parsecs. Such encounters could influence the solar system, for example through gravitational perturbations of the Oort cloud. 16 stars are found to come within 2pc (although a few of these have dubious data). This is fewer than were found in a similar study based on Hipparcos data, even though the present study has many more candidates. This is partly because I reject stars with large radial velocity uncertainties (>10km/s), and partly because of missing stars in GDR1 (especially at the bright end). The closest encounter found is Gl 710, a K dwarf long-known to come close to the Sun in about 1.3Myr. The Gaia astrometry predict a much closer passage than pre-Gaia estimates, however: just 16000AU (90% confidence interval: 10000-21000AU), which will bring this star well within the Oort cloud. Using a simple model for the spatial, velocity, and luminosity distributions of stars, together with an approximation of the observational selection function, I model the incompleteness of this Gaia-based search as a function of the time and distance of closest approach. Applying this to a subset of the observed encounters (excluding duplicates and stars with implausibly large velocities), I estimate the rate of stellar encounters within 5pc averaged over the past and future 5Myr to be 545+/-59Myr^-1^. Assuming a quadratic scaling of the rate within some encounter distance (which my model predicts), this corresponds to 87+/-9Myr-1 within 2pc. A more accurate analysis and assessment will be possible with future Gaia data releases.
17. Close encounters to the Sun in Gaia DR2
ID:
ivo://CDS.VizieR/J/A+A/616/A37
Title:
Close encounters to the Sun in Gaia DR2
Short Name:
J/A+A/616/A37
Date:
21 Oct 2021
Publisher:
CDS
Description:
Passing stars may play an important role in the evolution of our solar system. We search for close stellar encounters to the Sun among all 7.2 million stars in Gaia DR2 that have six-dimensional phase space data. We characterize encounters by integrating their orbits through a Galactic potential and propagating the correlated uncertainties via a Monte Carlo resampling. After filtering to remove spurious data, we find 694 stars that have median (over uncertainties) closest encounter distances within 5pc, all occurring within 15Myr from now. 26 of these have at least a 50% chance of coming closer than 1pc (and 7 within 0.5pc), all but one of which are newly discovered here. We confirm some and refute several other previously-identified encounters, confirming suspicions about their data. The closest encounter in the sample is Gl 710, which has a 95% probability of coming closer than 0.08pc (17000AU). Taking mass estimates obtained from Gaia astrometry and multiband photometry for essentially all encounters, we find that Gl 710 also has the largest impulse on the Oort cloud. Using a Galaxy model, we compute the completeness of the Gaia DR2 encountering sample as a function of perihelion time and distance. Only 15% of encounters within 5pc occurring within +/-5Myr of now have been identified, mostly due to the lack of radial velocities for faint and/or cool stars. Accounting for the incompleteness, we infer the present rate of encounters within 1pc to be 19.7+/-2.2 per Myr, a quantity expected to scale quadratically with the encounter distance out to at least several pc. Spuriously large parallaxes in our sample from imperfect filtering would tend to inflate both the number of encounters found and this inferred rate. The magnitude of this effect is hard to quantify.
18. Close star encounters
ID:
ivo://CDS.VizieR/J/A+A/575/A35
Title:
Close star encounters
Short Name:
J/A+A/575/A35
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stars which pass close to the Sun can perturb the Oort cloud, injecting comets into the inner solar system where they may collide with the Earth. Using van Leeuwen's re-reduction of the Hipparcos data complemented by the original Hipparcos and Tycho-2 catalogues, along with recent radial velocity surveys, I integrate the orbits of over 50000 stars through the Galaxy to look for close encounters. The search uses a Monte Carlo sampling of the covariance of the data in order to properly characterize the uncertainties in the times, distances, and speeds of the encounters.
19. 6 cold-gas-bearing debris-disc stars spectra
ID:
ivo://CDS.VizieR/J/A+A/614/A3
Title:
6 cold-gas-bearing debris-disc stars spectra
Short Name:
J/A+A/614/A3
Date:
21 Oct 2021
Publisher:
CDS
Description:
Debris discs have often been described as gas-poor discs as the gas-to-dust ratio is expected to be considerably lower than in primordial, protoplanetary discs. However, recent observations have confirmed the presence of a non-negligible amount of cold gas in the circumstellar (CS) debris discs around young main-sequence stars. This cold gas has been suggested to be related to the outgassing of planetesimals and cometary-like objects. The goal of this paper is to investigate the presence of hot gas in the immediate surroundings of the cold-gas-bearing debris-disc central stars. High-resolution optical spectra of all currently known cold-gas-bearing debris-disc systems, with the exception of beta Pic and Fomalhaut, have been obtained from La Palma (Spain), La Silla (Chile), and La Luz (Mexico) observatories. To verify the presence of hot gas around the sample of stars, we have analysed the CaII H&K and the NaI D lines searching for non-photospheric absorptions of CS origin, usually attributed to cometary-like activity.
20. Comet 46P/Wirtanen millimetre-wave spectra
ID:
ivo://CDS.VizieR/J/A+A/648/A49
Title:
Comet 46P/Wirtanen millimetre-wave spectra
Short Name:
J/A+A/648/A49
Date:
08 Feb 2022
Publisher:
CDS
Description:
We present the results of a molecular survey of comet 46P/Wirtanen undertaken with the IRAM 30-m and NOEMA radio telescopes in December 2018. Observations at IRAM 30-m during the 12-18 Dec. period comprise a 2mm spectral survey, which covers 25GHz, and a 1mm survey which covers 62GHz. The gas outflow velocity and kinetic temperature have been accurately constrained by the observations. We derive abundances of 11 molecules, some being identified remotely for the first time in a Jupiter-family comet, including complex organic molecules such as formamide, ethylene glycol, acetaldehyde or ethanol. Sensitive upper limits on the abundances of 24 other molecules are obtained. The comet is found to be relatively rich in methanol (3.4% relative to water) but relatively depleted in CO, CS, HNC, HNCO or HCOOH.