- ID:
- ivo://CDS.VizieR/J/ApJ/743/1
- Title:
- Astrometry of seven wide trans-Neptunian binaries
- Short Name:
- J/ApJ/743/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The low-inclination component of the Classical Kuiper Belt is host to a population of extremely widely separated binaries. These systems are similar to other trans-Neptunian binaries (TNBs) in that the primary and secondary components of each system are of roughly equal size. We have performed an astrometric monitoring campaign of a sample of seven wide-separation, long-period TNBs and present the first-ever well-characterized mutual orbits for each system. The sample contains the most eccentric (2006 CH_69_, e_m_=0.9) and the most widely separated, weakly bound (2001 QW_322_, a/R_H_~0.22) binary minor planets known, and also contains the system with lowest-measured mass of any TNB (2000 CF_105_, M_sys_~1.85x10^17^kg). Four systems orbit in a prograde sense, and three in a retrograde sense. They have a different mutual inclination distribution compared to all other TNBs, preferring low mutual-inclination orbits. These systems have geometric r-band albedos in the range of 0.09-0.3, consistent with radiometric albedo estimates for larger solitary low-inclination Classical Kuiper Belt objects, and we limit the plausible distribution of albedos in this region of the Kuiper Belt. We find that gravitational collapse binary formation models produce an orbital distribution similar to that currently observed, which along with a confluence of other factors supports formation of the cold Classical Kuiper Belt in situ through relatively rapid gravitational collapse rather than slow hierarchical accretion. We show that these binary systems are sensitive to disruption via collisions, and their existence suggests that the size distribution of TNOs at small sizes remains relatively shallow.
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- ID:
- ivo://CDS.VizieR/J/other/PSS/210.1
- Title:
- Astrometry of the 5 largest Uranian sat.
- Short Name:
- J/other/PSS/210.
- Date:
- 14 Dec 2021 08:12:44
- Publisher:
- CDS
- Description:
- We present the astrometry of the five largest satellites of Uranus from observations spread over almost three decades with photographic plates and CCDs (mainly), taken at the Pico dos Dias Observatory - Brazil. All positions presented here are obtained from the reanalysis of measurements and images used in previous publications. Reference stars are those from the Gaia Early Data Release 3 (Gaia EDR3) allowing, in addition to a higher accuracy, a larger number of positions of the largest satellites as compared to our previous works. From 1982 to 1987, positions were obtained from photographic plates. From 1989 to 2011, CCDs were used. On average, we obtained {Delta}{alpha}cos{delta}=-11(+/-52) milli-arcseconds and {delta}{delta}=-14 (+/-43) milli-arcseconds for the differences in the sense observation minus ephemerides (DE435+ura111). Comparisons with different ephemerides (DE440, INPOP21a, INPOP19a and NOE-7-2013-MAIN) and results from stellar occultations indicate a possible offset in the (Solar System) barycentric position of the Uranian system barycenter. Overall, our results are useful to improve dynamical models of the Uranian largest satellites as well as the orbit of Uranus.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A8
- Title:
- Astrometry of the main satellites of Uranus
- Short Name:
- J/A+A/582/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine accurate positions of the main satellites of Uranus: Miranda, Ariel, Umbriel, Titania, and Oberon. Positions of Uranus, as derived from those of these satellites, are also determined. The observational period spans from 1992 to 2011. All runs were made at the Pico dos Dias Observatory, Brazil. We used the software called Platform for Reduction of Astronomical Images Automatically (PRAIA) to perform a digital coronography to minimise the influence of the scattered light of Uranus on the astrometric measurements and to determine accurate positions of the main satellites. The positions of Uranus were then indirectly determined by computing the mean differences between the observed and ephemeris positions of these satellites. A series of numerical filters was applied to filter out spurious data. These filters are mostly based on (a) the comparison between the positions of Oberon with those of the other satellites and on (b) the offsets as given by the differences between the observed and ephemeris positions of all satellites. We have, for the overall offsets of the five satellites, -29mas (+/-63mas) in right ascension and -27mas (+/-46mas) in declination. For the overall difference between the offsets of Oberon and those of the other satellites, we have +3mas (+/-30mas) in right ascension and -2mas (+/-28mas) in declination. Ephemeris positions for the satellites were determined from DE432+ura111.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A73
- Title:
- Astrometry of the Saturnian satellites 2004-12
- Short Name:
- J/A+A/575/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cassini spacecraft has been orbiting Saturn since 2004 returning images of satellites with astrometric resolution as high as few hundreds of meters. The images that were taken by the Narrow Angle Camera (NAC) of Image Science Subsystem (ISS) instrument on board Cassini, were used in this work for the purpose of astrometry. We applied the same method that was previously developed to reduce Cassini NAC images of Mimas and Enceladus. We provide 5240 astrometric positions in right ascension and declination of the satellites: Tethys, Dione, Rhea, Iapetus, and Phoebe, using images that were taken by Cassini NAC between 2004 and 2012. Mean residuals compared to the JPL ephemeris SAT365 are of the order of hundreds of meters with standard deviations of the order of few kilometers. Frequency analysis of the residuals shows the remaining non-modeled effects of satellites on others.
- ID:
- ivo://CDS.VizieR/J/AcA/50/221
- Title:
- Astrometry of variable stars in M 3
- Short Name:
- J/AcA/50/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present identification and astrometry of all previously known or suspected variables along with the discovery of six new variables in the globular cluster M3. The number of the catalogued variables increased to 274 by including all the confirmed, previously known variables and the new discoveries. The precise and homogeneous astrometry, as well as the clarification of misapprehensions in the preceding identifications are done by using overlapping fields from a wide-field Schmidt-camera, 1-m RCC telescope, and HST archive observations from the center of the cluster. The astrometric positions can serve as a direct input to any photometry which needs the accurate centers of the variables.
- ID:
- ivo://CDS.VizieR/J/other/NewA/36.70
- Title:
- Astrometry of 3 vdBH open clusters
- Short Name:
- J/other/NewA/36.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a study that combines photometry and astrometry for the open clusters vdB80, vdB85 and vdB130. We apply a model which analyses the proper motion distribution and the stellar density to find the kinematic parameters and stellar membership in the region of the mentioned open clusters. The astrometric data are obtained from UCAC4 catalogue.
- ID:
- ivo://CDS.VizieR/J/AJ/161/133
- Title:
- Astrometry & photometry for CMa R1 members
- Short Name:
- J/AJ/161/133
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- An exotic environment surrounds the young stellar groups associated with the Canis Major (CMa) OB1/R1 region, which probably was formed under feedback from at least three supernova events having occurred a few million years ago. We use astrometric data from the Gaia-DR2 to confirm the membership of the stars in CMa R1, based on proper motion and parallax, which revealed 514 new members and candidates. The mean age of 5Myr estimated from the color-magnitude diagram characterizes the sources as likely pre-main-sequence candidates. In total, a sample of 694 stars detected with the T80-South telescope was analyzed according to different color-color diagrams, which were compared with theoretical colors from evolutionary models, aiming to reveal the objects that exhibit color excess due to accretion processes. Accretion and magnetic activity were also explored on the basis of empirical flux-flux relation, such as F660 and F861 that are related to H{alpha} and CaII triplet emission, respectively. A low fraction (~3%) of the sample have H{alpha} excess and other colors expected for stars exhibiting chromospheric activity. The number of Class I and Class II objects, identified by the infrared (Wide-field Infrared Survey Explorer) colors, indicates a disk fraction of ~6%, which is lower than that expected for stellar clusters with a similar age. Such a large sample of objects associated with CMa R1 without evidences of circumstellar accretion can be interpreted as a lack of disk-bearing stars, unusual for young star-forming regions. However, this may be explained as the result of supernova events.
- ID:
- ivo://CDS.VizieR/J/AJ/154/147
- Title:
- Astrometry&photometry for late-type dwarfs&subdwarfs
- Short Name:
- J/AJ/154/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New, updated, and/or revised CCD parallaxes determined with the Strand Astrometric Reflector at the Naval Observatory Flagstaff Station are presented. Included are results for 309 late-type dwarf and subdwarf stars observed over the 30+ years that the program operated. For 124 of the stars, parallax determinations from other investigators have already appeared in the literature and we compare the different results. Also included here are new or updated VI photometry on the Johnson-Kron-Cousins system for all but a few of the faintest targets. Together with 2MASS JHK_s_ near-infrared photometry, a sample of absolute magnitude versus color and color versus color diagrams are constructed. Because large proper motion was a prime criterion for targeting the stars, the majority turn out to be either M-type subdwarfs or late M-type dwarfs. The sample also includes 50 dwarf or subdwarf L-type stars, and four T dwarfs. Possible halo subdwarfs are identified in the sample based on tangential velocity, subluminosity, and spectral type. Residuals from the solutions for parallax and proper motion for several stars show evidence of astrometric perturbations.
- ID:
- ivo://CDS.VizieR/J/AJ/155/252
- Title:
- Astrometry & photometry of dwarf carbon stars
- Short Name:
- J/AJ/155/252
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parallaxes are presented for a sample of 20 nearby dwarf carbon stars. The inferred luminosities cover almost two orders of magnitude. Their absolute magnitudes and tangential velocities confirm prior expectations that some originate in the Galactic disk, although more than half of this sample are halo stars. Three stars are found to be astrometric binaries, and orbital elements are determined; their semimajor axes are 1-3 au, consistent with the size of an AGB mass-transfer donor star.
- ID:
- ivo://CDS.VizieR/J/AJ/162/14
- Title:
- Astrometry & radial velocity, Alpha Centauri system
- Short Name:
- J/AJ/162/14
- Date:
- 14 Mar 2022 06:46:54
- Publisher:
- CDS
- Description:
- Alpha Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its habitable zone. Here, we describe initial results from an Atacama Large Millimeter/submillimeter Array (ALMA) program to search for planets in the {alpha} Cen AB system using differential astrometry at millimeter wavelengths. Our initial results include new absolute astrometric measurements of the proper motion, orbital motion and parallax of the {alpha} Cen system. These lead to an improved knowledge of the physical properties of both {alpha} Cen A and B. Our estimates of ALMA's relative astrometric precision suggest that we will ultimately be sensitive to planets of a few tens of Earth mass in orbits from 1 to 3au, where stable orbits are thought to exist.
