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F Bragaribas - One of the best experts on this subject based on the ideXlab platform.
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stellar Occultations enable milliarcsecond astrometry for trans neptunian objects and centaurs
arXiv: Earth and Planetary Astrophysics, 2020Co-Authors: F L Rommel, J L Ortiz, F Bragaribas, J I B Camargo, M Assafin, R Vieiramartins, J Desmars, P SantossanzAbstract:Trans-Neptunian objects (TNOs) and Centaurs are remnants of our planetary system formation, and their physical properties have invaluable information for evolutionary theories. Stellar Occultation is a ground-based method for studying these small bodies and has presented exciting results. These observations can provide precise profiles of the involved body, allowing an accurate determination of its size and shape. The goal is to show that even single-chord detections of TNOs allow us to measure their milliarcsecond astrometric positions in the reference frame of the Gaia second data release (DR2). Accurated ephemerides can then be generated, allowing predictions of stellar Occultations with much higher reliability. We analyzed data from stellar Occultations to obtain astrometric positions of the involved bodies. The events published before the Gaia era were updated so that the Gaia DR2 catalog is the reference. Previously determined sizes were used to calculate the position of the object center and its corresponding error with respect to the detected chord and the International Celestial Reference System (ICRS) propagated Gaia DR2 star position. We derive 37 precise astrometric positions for 19 TNOs and 4 Centaurs. Twenty-one of these events are presented here for the first time. Although about 68\% of our results are based on single-chord detection, most have intrinsic precision at the submilliarcsecond level. Lower limits on the diameter and shape constraints for a few bodies are also presented as valuable byproducts. Using the Gaia DR2 catalog, we show that even a single detection of a stellar Occultation allows improving the object ephemeris significantly, which in turn enables predicting a future stellar Occultation with high accuracy. Observational campaigns can be efficiently organized with this help, and may provide a full physical characterization of the involved object.
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the first observed stellar Occultations by the irregular satellite phoebe saturn ix and improved rotational period
Monthly Notices of the Royal Astronomical Society, 2020Co-Authors: F Bragaribas, J I B Camargo, G Benedettirossi, A R Gomesjunior, M Assafin, R Vieiramartins, B E MorgadoAbstract:We report six stellar Occultations by (Saturn IX) Phoebe, an irregular satellite of Saturn, obtained between mid-2017 and mid-2019. The 2017 July 06 event is the first stellar Occultation by an irregular satellite ever observed. The Occultation chords were compared to a 3D shape model of the satellite obtained from Cassini observations. The rotation period available in the literature led to a sub-observer point at the moment of the observed Occultations where the chords could not fit the 3D model. A procedure was developed to identify the correct sub-observer longitude. It allowed us to obtain the rotation period with improved precision over currently known value from literature. We show that the difference between the observed and the predicted sub-observer longitude suggests two possible solutions for the rotation period. By comparing these values with recently observed rotational light curves and single-chord stellar Occultations, we can identify the best solution for Phoebe's rotational period as $9.27365 \pm 0.00002$ h. From the stellar Occultations, we also obtained 6 geocentric astrometric positions in the ICRS as realised by the Gaia-DR2 with uncertainties at the 1-mas level.
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first stellar Occultation by the galilean moon europa and upcoming events between 2019 and 2021
Astronomy and Astrophysics, 2019Co-Authors: B Morgado, F Bragaribas, J I B Camargo, G Benedettirossi, A R Gomesjunior, M Assafin, V Lainey, R VieiramartinsAbstract:Context . Bright stellar positions are now known with an uncertainty below 1 mas thanks to Gaia DR2. Between 2019–2020, the Galactic plane will be the background of Jupiter. The dense stellar background will lead to an increase in the number of Occultations, while the Gaia DR2 catalogue will reduce the prediction uncertainties for the shadow path.Aims . We observed a stellar Occultation by the Galilean moon Europa (J2) and propose a campaign for observing stellar Occultations for all Galilean moons.Methods . During a predicted period of time, we measured the light flux of the occulted star and the object to determine the time when the flux dropped with respect to one or more reference stars, and the time that it rose again for each observational station. The chords obtained from these observations allowed us to determine apparent sizes, oblatness, and positions with kilometre accuracy.Results . We present results obtained from the first stellar Occultation by the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse presents an equivalent radius of 1561.2 ± 3.6 km and oblatenesses 0.0010 ± 0.0028. A very precise Europa position was determined with an uncertainty of 0.8 mas. We also present prospects for a campaign to observe the future events that will occur between 2019 and 2021 for all Galilean moons.Conclusions . Stellar Occultation is a suitable technique for obtaining physical parameters and highly accurate positions of bright satellites close to their primary. A number of successful events can render the 3D shapes of the Galilean moons with high accuracy. We encourage the observational community (amateurs included) to observe the future predicted events.
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results from a triple chord stellar Occultation and far infrared photometry of the trans neptunian object 229762 2007 uk126
Astronomy and Astrophysics, 2017Co-Authors: J L Ortiz, Jurgen Wolf, Karsten Schindler, Jerry Bardecker, Aart M Olsen, Thomas Muller, Csaba Kiss, F BragaribasAbstract:Context. A stellar Occultation by a trans-Neptunian object (TNO) provides an opportunity to probe the size and shape of these distant solar system bodies. In the past seven years, several Occultations by TNOs have been observed, but mostly from a single location. Only very few TNOs have been sampled simultaneously from multiple locations. Sufficient data that enable a robust estimation of shadow size through an ellipse fit could only be obtained for two objects.Aims. We present the first observation of an Occultation by the TNO 2007 UK126 on 15 November 2014, measured by three observers, one nearly on and two almost symmetrical to the shadow’s centerline. This is the first multi-chord dataset obtained for a so-called detached object, a TNO subgroup with perihelion distances so large that the giant planets have likely not perturbed their orbits. We also revisit Herschel /PACS far-infrared data, applying a new reduction method to improve the accuracy of the measured fluxes. Combining both datasets allows us to comprehensively characterize 2007 UK126 .Methods. We use error-in-variable regression to solve the non-linear problem of propagating timing errors into uncertainties of the ellipse parameters. Based on the shadow’s size and a previously reported rotation period, we expect a shape of a Maclaurin spheroid and derive a geometrically plausible size range. To refine our size estimate of 2007 UK126 , we model its thermal emission using a thermophysical model code. We conduct a parametric study to predict far-infrared fluxes and compare them to the Herschel /PACS measurements.Results. The favorable geometry of our Occultation chords, combined with minimal dead-time imaging, and precise GPS time measurements, allow for an accurate estimation of the shadow size (best-fitting ellipse with axes 645.80 ± 5.68 km × 597.81 ± 12.74 km) and the visual geometric albedo (p V = 15.0 ± 1.6%). By combining our analyses of the Occultation and the far-infrared data, we can constrain the effective diameter of 2007 UK126 to d eff = 599−629 km. We conclude that subsolar surface temperatures are in the order of ≈ 50−55 K.
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results from a triple chord stellar Occultation and far infrared photometry of the trans neptunian object 229762 2007 uk126
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: J L Ortiz, Jurgen Wolf, Karsten Schindler, Jerry Bardecker, Aart M Olsen, Thomas Muller, Csaba Kiss, F BragaribasAbstract:A stellar Occultation by a trans-Neptunian object (TNO) provides an opportunity to probe its size and shape. Very few Occultations by TNOs have been sampled simultaneously from multiple locations, while a robust estimation of shadow size has been possible for only two objects. We present the first observation of an Occultation by the TNO 2007 UK126 on 15 November 2014, measured by three observers, one nearly on and two almost symmetrical to the shadow's centerline. This is the first multi-chord dataset obtained for a so-called detached object, a TNO subgroup with perihelion distances so large that the giant planets have likely not perturbed their orbits. We revisit Herschel/PACS far-infrared data, applying a new reduction method to improve the accuracy of the measured fluxes. Combining both datasets allows us to comprehensively characterize 2007 UK126. We use error-in-variable regression to solve the non-linear problem of propagating timing errors into uncertainties of the ellipse parameters. Based on the shadow's size and a previously reported rotation period, we expect a shape of a Maclaurin spheroid and derive a geometrically plausible size range. To refine our size estimate of 2007 UK126, we model its thermal emission using a thermophysical model code. We conduct a parametric study to predict far-infrared fluxes and compare them to the Herschel/PACS measurements. The favorable geometry of our Occultation chords, combined with minimal dead-time imaging, and precise GPS time measurements, allow for an accurate estimation of the shadow size (best-fitting ellipse with axes 645.80 $\pm$ 5.68 km $\times$ 597.81 $\pm$ 12.74 km) and the visual geometric albedo (15.0 $\pm$ 1.6 %). By combining our analyses of the Occultation and the far-infrared data, we can constrain the effective diameter of 2007 UK126 to 599 - 629 km. We conclude that subsolar surface temperatures are $\approx$ 50 - 55 K.
M J Lehner - One of the best experts on this subject based on the ideXlab platform.
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the taos project upper bounds on the population of small kuiper belt objects and tests of models of formation and evolution of the outer solar system
The Astronomical Journal, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S MondalAbstract:We have analyzed the first 3.75 years of data from the Taiwanese American Occultation Survey (TAOS). TAOS monitors bright stars to search for Occultations by Kuiper Belt objects (KBOs). This data set comprises 5 × 10^5 star hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this data set. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari, Kenyon & Bromley, Benavidez & Campo Bagatin, and Fraser. A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is composed of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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the taos project upper bounds on the population of small kbos and tests of models of formation and evolution of the outer solar system
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S Mondal, M J Holman, N K Coehlo, J H Wang, C AlcockAbstract:We have analyzed the first 3.75 years of data from TAOS, the Taiwanese American Occultation Survey. TAOS monitors bright stars to search for Occultations by Kuiper Belt Objects (KBOs). This dataset comprises 5e5 star-hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this dataset. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari (2005), Kenyon & Bromley (2004), Benavidez & Campo Bagatin (2009), and Fraser (2009). A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is comprised of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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a search for Occultations of bright stars by small kuiper belt objects using megacam on the mmt
The Astronomical Journal, 2009Co-Authors: M J Lehner, F B Bianco, C Alcock, Pavlos Protopapas, B A Mcleod, Matthew J HolmanAbstract:We conducted a search for Occultations of bright stars by Kuiper Belt Objects (KBOs) to estimate the density of subkilometer KBOs in the sky. We report here the first results of this Occultation survey of the outer solar system conducted in 2007 June and 2008 June/July at the MMT Observatory using Megacam, the large MMT optical imager. We used Megacam in a novel shutterless continuous-readout mode to achieve high-precision photometry at 200?Hz, which with point-spread function convolution results in an effective sampling of ~30 Hz. We present an analysis of 220 star hours of data at a signal-to-noise ratio of 25?or greater, taken from images of fields within 3? of the ecliptic plane. The survey efficiency is greater than 10% for Occultations by KBOs of diameter d ? 0.7 km, and we report no detections in our data set. We set a new 95% confidence level upper limit for the surface density ? N (d) of KBOs larger than 1?km: ? N (d ? 1 km) ? 2.0 ? 108 deg?2, and for KBOs larger than 0.7 km ? N (d ? 0.7 km) ? 4.8 ? 108 deg?2.
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a search for Occultations of bright stars by small kuiper belt objects using megacam on the mmt
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: M J Lehner, F B Bianco, C Alcock, Pavlos Protopapas, B A Mcleod, Matthew J HolmanAbstract:We conducted a search for Occultations of bright stars by Kuiper Belt Objects (KBOs) to estimate the density of sub-km KBOs in the sky. We report here the first results of this Occultation survey of the outer solar system conducted in June 2007 and June/July 2008 at the MMT Observatory using Megacam, the large MMT optical imager. We used Megacam in a novel shutterless continuous--readout mode to achieve high precision photometry at 200 Hz. We present an analysis of 220 star hours at signal-to-noise ratio of 25 or greater. The survey efficiency is greater than 10% for Occultations by KBOs of diameter d>=0.7 km, and we report no detections in our dataset. We set a new 95% confidence level upper limit for the surface density \Sigma_N(d) of KBOs larger than 1 km: \Sigma_N(d>=1 km) = 0.7 km) <= 4.8e8 deg^-2.
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detectability of Occultations of stars by objects in the kuiper belt and oort cloud
The Astronomical Journal, 2007Co-Authors: T C Nihei, M J Lehner, F B Bianco, S K King, J M Giammarco, C AlcockAbstract:The serendipitous detection of stellar Occultations by outer solar system objects is a powerful method for ascertaining the small end (r 15 km) of the size distribution of Kuiper Belt objects and may potentially allow the exploration of objects as far out as the Oort Cloud. The design and implementation of an Occultation survey is aided by a detailed understanding of how diffraction and observational parameters affect the detection of Occultation events. In this study, stellar Occultations are simulated, accounting for diffraction effects, finite source sizes, finite bandwidths, stellar spectra, sampling, and signal-to-noise ratios. Finally, the possibility of detecting small outer solar system objects from the Kuiper Belt all the way out to the Oort Cloud is explored for three photometric systems: a proposed space telescope, Whipple, the Taiwanese-American Occultation Survey, and the MMT.
F B Bianco - One of the best experts on this subject based on the ideXlab platform.
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the taos project upper bounds on the population of small kuiper belt objects and tests of models of formation and evolution of the outer solar system
The Astronomical Journal, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S MondalAbstract:We have analyzed the first 3.75 years of data from the Taiwanese American Occultation Survey (TAOS). TAOS monitors bright stars to search for Occultations by Kuiper Belt objects (KBOs). This data set comprises 5 × 10^5 star hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this data set. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari, Kenyon & Bromley, Benavidez & Campo Bagatin, and Fraser. A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is composed of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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the taos project upper bounds on the population of small kbos and tests of models of formation and evolution of the outer solar system
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S Mondal, M J Holman, N K Coehlo, J H Wang, C AlcockAbstract:We have analyzed the first 3.75 years of data from TAOS, the Taiwanese American Occultation Survey. TAOS monitors bright stars to search for Occultations by Kuiper Belt Objects (KBOs). This dataset comprises 5e5 star-hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this dataset. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari (2005), Kenyon & Bromley (2004), Benavidez & Campo Bagatin (2009), and Fraser (2009). A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is comprised of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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a search for Occultations of bright stars by small kuiper belt objects using megacam on the mmt
The Astronomical Journal, 2009Co-Authors: M J Lehner, F B Bianco, C Alcock, Pavlos Protopapas, B A Mcleod, Matthew J HolmanAbstract:We conducted a search for Occultations of bright stars by Kuiper Belt Objects (KBOs) to estimate the density of subkilometer KBOs in the sky. We report here the first results of this Occultation survey of the outer solar system conducted in 2007 June and 2008 June/July at the MMT Observatory using Megacam, the large MMT optical imager. We used Megacam in a novel shutterless continuous-readout mode to achieve high-precision photometry at 200?Hz, which with point-spread function convolution results in an effective sampling of ~30 Hz. We present an analysis of 220 star hours of data at a signal-to-noise ratio of 25?or greater, taken from images of fields within 3? of the ecliptic plane. The survey efficiency is greater than 10% for Occultations by KBOs of diameter d ? 0.7 km, and we report no detections in our data set. We set a new 95% confidence level upper limit for the surface density ? N (d) of KBOs larger than 1?km: ? N (d ? 1 km) ? 2.0 ? 108 deg?2, and for KBOs larger than 0.7 km ? N (d ? 0.7 km) ? 4.8 ? 108 deg?2.
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a search for Occultations of bright stars by small kuiper belt objects using megacam on the mmt
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: M J Lehner, F B Bianco, C Alcock, Pavlos Protopapas, B A Mcleod, Matthew J HolmanAbstract:We conducted a search for Occultations of bright stars by Kuiper Belt Objects (KBOs) to estimate the density of sub-km KBOs in the sky. We report here the first results of this Occultation survey of the outer solar system conducted in June 2007 and June/July 2008 at the MMT Observatory using Megacam, the large MMT optical imager. We used Megacam in a novel shutterless continuous--readout mode to achieve high precision photometry at 200 Hz. We present an analysis of 220 star hours at signal-to-noise ratio of 25 or greater. The survey efficiency is greater than 10% for Occultations by KBOs of diameter d>=0.7 km, and we report no detections in our dataset. We set a new 95% confidence level upper limit for the surface density \Sigma_N(d) of KBOs larger than 1 km: \Sigma_N(d>=1 km) = 0.7 km) <= 4.8e8 deg^-2.
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detectability of Occultations of stars by objects in the kuiper belt and oort cloud
The Astronomical Journal, 2007Co-Authors: T C Nihei, M J Lehner, F B Bianco, S K King, J M Giammarco, C AlcockAbstract:The serendipitous detection of stellar Occultations by outer solar system objects is a powerful method for ascertaining the small end (r 15 km) of the size distribution of Kuiper Belt objects and may potentially allow the exploration of objects as far out as the Oort Cloud. The design and implementation of an Occultation survey is aided by a detailed understanding of how diffraction and observational parameters affect the detection of Occultation events. In this study, stellar Occultations are simulated, accounting for diffraction effects, finite source sizes, finite bandwidths, stellar spectra, sampling, and signal-to-noise ratios. Finally, the possibility of detecting small outer solar system objects from the Kuiper Belt all the way out to the Oort Cloud is explored for three photometric systems: a proposed space telescope, Whipple, the Taiwanese-American Occultation Survey, and the MMT.
J M Giammarco - One of the best experts on this subject based on the ideXlab platform.
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the taos project upper bounds on the population of small kuiper belt objects and tests of models of formation and evolution of the outer solar system
The Astronomical Journal, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S MondalAbstract:We have analyzed the first 3.75 years of data from the Taiwanese American Occultation Survey (TAOS). TAOS monitors bright stars to search for Occultations by Kuiper Belt objects (KBOs). This data set comprises 5 × 10^5 star hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this data set. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari, Kenyon & Bromley, Benavidez & Campo Bagatin, and Fraser. A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is composed of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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the taos project upper bounds on the population of small kbos and tests of models of formation and evolution of the outer solar system
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: F B Bianco, M J Lehner, S K King, J M Giammarco, Zw Zhang, S Mondal, M J Holman, N K Coehlo, J H Wang, C AlcockAbstract:We have analyzed the first 3.75 years of data from TAOS, the Taiwanese American Occultation Survey. TAOS monitors bright stars to search for Occultations by Kuiper Belt Objects (KBOs). This dataset comprises 5e5 star-hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO Occultations were found in this dataset. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari (2005), Kenyon & Bromley (2004), Benavidez & Campo Bagatin (2009), and Fraser (2009). A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an Occultation survey. Our results suggest that the KBO population is comprised of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
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detectability of Occultations of stars by objects in the kuiper belt and oort cloud
The Astronomical Journal, 2007Co-Authors: T C Nihei, M J Lehner, F B Bianco, S K King, J M Giammarco, C AlcockAbstract:The serendipitous detection of stellar Occultations by outer solar system objects is a powerful method for ascertaining the small end (r 15 km) of the size distribution of Kuiper Belt objects and may potentially allow the exploration of objects as far out as the Oort Cloud. The design and implementation of an Occultation survey is aided by a detailed understanding of how diffraction and observational parameters affect the detection of Occultation events. In this study, stellar Occultations are simulated, accounting for diffraction effects, finite source sizes, finite bandwidths, stellar spectra, sampling, and signal-to-noise ratios. Finally, the possibility of detecting small outer solar system objects from the Kuiper Belt all the way out to the Oort Cloud is explored for three photometric systems: a proposed space telescope, Whipple, the Taiwanese-American Occultation Survey, and the MMT.
Karsten Schindler - One of the best experts on this subject based on the ideXlab platform.
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results from a triple chord stellar Occultation and far infrared photometry of the trans neptunian object 229762 2007 uk126
Astronomy and Astrophysics, 2017Co-Authors: J L Ortiz, Jurgen Wolf, Karsten Schindler, Jerry Bardecker, Aart M Olsen, Thomas Muller, Csaba Kiss, F BragaribasAbstract:Context. A stellar Occultation by a trans-Neptunian object (TNO) provides an opportunity to probe the size and shape of these distant solar system bodies. In the past seven years, several Occultations by TNOs have been observed, but mostly from a single location. Only very few TNOs have been sampled simultaneously from multiple locations. Sufficient data that enable a robust estimation of shadow size through an ellipse fit could only be obtained for two objects.Aims. We present the first observation of an Occultation by the TNO 2007 UK126 on 15 November 2014, measured by three observers, one nearly on and two almost symmetrical to the shadow’s centerline. This is the first multi-chord dataset obtained for a so-called detached object, a TNO subgroup with perihelion distances so large that the giant planets have likely not perturbed their orbits. We also revisit Herschel /PACS far-infrared data, applying a new reduction method to improve the accuracy of the measured fluxes. Combining both datasets allows us to comprehensively characterize 2007 UK126 .Methods. We use error-in-variable regression to solve the non-linear problem of propagating timing errors into uncertainties of the ellipse parameters. Based on the shadow’s size and a previously reported rotation period, we expect a shape of a Maclaurin spheroid and derive a geometrically plausible size range. To refine our size estimate of 2007 UK126 , we model its thermal emission using a thermophysical model code. We conduct a parametric study to predict far-infrared fluxes and compare them to the Herschel /PACS measurements.Results. The favorable geometry of our Occultation chords, combined with minimal dead-time imaging, and precise GPS time measurements, allow for an accurate estimation of the shadow size (best-fitting ellipse with axes 645.80 ± 5.68 km × 597.81 ± 12.74 km) and the visual geometric albedo (p V = 15.0 ± 1.6%). By combining our analyses of the Occultation and the far-infrared data, we can constrain the effective diameter of 2007 UK126 to d eff = 599−629 km. We conclude that subsolar surface temperatures are in the order of ≈ 50−55 K.
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results from a triple chord stellar Occultation and far infrared photometry of the trans neptunian object 229762 2007 uk126
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: J L Ortiz, Jurgen Wolf, Karsten Schindler, Jerry Bardecker, Aart M Olsen, Thomas Muller, Csaba Kiss, F BragaribasAbstract:A stellar Occultation by a trans-Neptunian object (TNO) provides an opportunity to probe its size and shape. Very few Occultations by TNOs have been sampled simultaneously from multiple locations, while a robust estimation of shadow size has been possible for only two objects. We present the first observation of an Occultation by the TNO 2007 UK126 on 15 November 2014, measured by three observers, one nearly on and two almost symmetrical to the shadow's centerline. This is the first multi-chord dataset obtained for a so-called detached object, a TNO subgroup with perihelion distances so large that the giant planets have likely not perturbed their orbits. We revisit Herschel/PACS far-infrared data, applying a new reduction method to improve the accuracy of the measured fluxes. Combining both datasets allows us to comprehensively characterize 2007 UK126. We use error-in-variable regression to solve the non-linear problem of propagating timing errors into uncertainties of the ellipse parameters. Based on the shadow's size and a previously reported rotation period, we expect a shape of a Maclaurin spheroid and derive a geometrically plausible size range. To refine our size estimate of 2007 UK126, we model its thermal emission using a thermophysical model code. We conduct a parametric study to predict far-infrared fluxes and compare them to the Herschel/PACS measurements. The favorable geometry of our Occultation chords, combined with minimal dead-time imaging, and precise GPS time measurements, allow for an accurate estimation of the shadow size (best-fitting ellipse with axes 645.80 $\pm$ 5.68 km $\times$ 597.81 $\pm$ 12.74 km) and the visual geometric albedo (15.0 $\pm$ 1.6 %). By combining our analyses of the Occultation and the far-infrared data, we can constrain the effective diameter of 2007 UK126 to 599 - 629 km. We conclude that subsolar surface temperatures are $\approx$ 50 - 55 K.
