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Y Lebreton - One of the best experts on this subject based on the ideXlab platform.
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asteroseismology for a la carte stellar Age Dating and weighing Age and mass of the corot exoplanet host hd 52265
Astronomy and Astrophysics, 2014Co-Authors: Y Lebreton, Mariejo GoupilAbstract:Context. In the context of the space missions CoRoT, Kepler, Gaia, TESS, and PLATO, precise and accurate stellar Ages, masses, and radii are of paramount importance. For instance, they are crucial for constraining scenarii of planetary formation and evolution. Aims. We aim at quantifying how detailed stellar modelling can improve the accuracy and precision on Age and mass of individual stars. To that end, we adopt a multifaceted approach where we carefully examine how the number of observational constraints as well as the uncertainties on observations and on model input physics affect the results of Age-Dating and weighing. Methods. We modelled in detail the exoplanet host-star HD 52265, a main-sequence, solar-like oscillator that CoRoT observed for four months. We considered different sets of observational constraints (Hertzsprung-Russell data, metallicity, various sets of seismic constraints). For each case, we determined the Age, mass, and properties of HD 52265 inferred from stellar models, and we quantified the impact of the model input physics and free parameters. We also compared model Ages with Ages derived by empirical methods or Hertzsprung-Russell diagram inversion. Results. For our case study HD 52265, our seismic analysis provides an Age A = 2.10−2.54 Gyr, a mass M = 1.14−1.32 M� ,a nd a radius R = 1.30−1.34 R� , which corresponds to Age, mass, and radius uncertainties of ∼10, ∼7, and ∼1.5 per cent, respectively. These uncertainties account for observational errors and current state-of-the-art stellar model uncertainties. Our seismic study also provides constraints on surface convection properties through the mixing-length, which we find to be 12−15 per cent lower than the solar value. On the other hand, because of helium-mass degeneracy, the initial helium abundance is determined modulo the mass value. Finally, we evaluate the seismic mass of the exoplanet to be Mp sini = 1.17−1.26 MJupiter, much more precise than what can be derived by Hertzsprung-Russell diagram inversion. Conclusions. We demonstrate that asteroseismology allows us to substantially improve the Age accuracy that can be achieved with other methods. We emphasize that the knowledge of the mean properties of stellar oscillations – such as the large frequency separation – is not enough to derive accurate Ages. We need precise individual frequencies to narrow the Age scatter that is a result of the model input physics uncertainties. Further progress is required to better constrain the physics at work in stars and the stars helium content. Our results emphasize the importance of precise classical stellar parameters and oscillation frequencies such as will be obtained by the Gaia and PLATO missions.
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asteroseismology for a la carte stellar Age Dating and weighing Age and mass of the corot exoplanet host hd 52265
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: Y Lebreton, Mariejo GoupilAbstract:In the context of CoRoT, Kepler, Gaia, TESS, and PLATO, precise and accurate stellar Ages, masses and radii are of paramount importance. They are crucial to constrain scenarii of planetary formation and evolution.We aim at quantifying how detailed stellar modeling improves the accuracy and precision on Age and mass of individual stars. We adopt a multifaceted approach where we examine how the number of observational constraints as well as the uncertainties on observations and on model input physics impact the Age-Dating and weighing. We modelled the exoplanet host-star HD52265, a MS, solar-like oscillator observed by CoRoT. We considered different sets of observational constraints (HR data, metallicity, seismic constraints). For each case, we determined the Age, mass, and properties of HD52265 inferred from models, and quantified the impact of the models inputs. Our seismic analysis provides an Age A=2.10-2.54 Gyr, a mass M=1.14-1.32 Msun, and a radius R=1.30-1.34 Rsun, which corresponds to uncertainties of 10, 7, and 1.5% respectively. Our seismic study provides constraints on surface convection, through the mixing-length found to be 12-15% smaller than the solar one. Because of helium-mass degeneracy, the initial He abundance is determined modulo the mass. The seismic mass of the exoplanet is found to be Mp sin i=1.17-1.26 MJup, much more precise than what can be derived by HR diagram inversion. We demonstrate that asteroseismology allows to improve the Age accuracy compared to other methods. We emphasize that the knowledge of the mean properties of oscillations -as the large frequency separation- is not enough for deriving accurate Ages. We need precise individual frequencies to narrow the Age scatter due to model uncertainties. This strengthen the case for precise classical stellar parameters and frequencies as will be obtained by Gaia and PLATO.
Stefan Winkler - One of the best experts on this subject based on the ideXlab platform.
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schmidt hammer exposure Ages from periglacial patterned ground sorted circles in jotunheimen norway and their interpretative problems
Geografiska Annaler Series A-physical Geography, 2016Co-Authors: Stefan Winkler, John A Matthews, Richard W Mourne, P WilsonAbstract:Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt‐hammer exposure‐Age Dating ...
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schmidt hammer exposure Age Dating shd of late quaternary fluvial terraces in new zealand
Earth Surface Processes and Landforms, 2013Co-Authors: T Stahl, Stefan Winkler, M Quigley, Mark Bebbington, Brendan Duffy, Daniel DukeAbstract:Schmidt hammer (SH) R-values are reported for surface clasts from numerically dated Holocene and Pleistocene fluvial terraces in the South Island of New Zealand. The R-values are combined with previously obtained weathering rind, radiocarbon, terrestrial cosmogenic nuclide and luminescence terrace Ages to derive SH R-value chronofunctions for greywacke clasts from four distinct locations. Our results show that different weathering rates affect the form of the SH R-value versus Age curve, however a fundamental dependency between the two remains constant over timescales ranging from 102 to 105 years. Power law scaling constants suggest changes in clast weathering rates are primarily affected by climatic (precipitation and temperature) and sedimentologic variables (source terrane petrology). Age uncertainties of ~22% of the surface Age suggest that Schmidt hammer exposure-Age Dating (SHD) is a reliable calibrated-Age Dating technique for fluvial terraces. Copyright © 2013 John Wiley & Sons, Ltd.
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schmidt hammer exposure Age Dating shd application to early holocene moraines and a reappraisal of the reliability of terrestrial cosmogenic nuclide Dating tcnd at austanbotnbreen jotunheimen norway
Boreas, 2011Co-Authors: John A Matthews, Stefan WinklerAbstract:Matthews, J. A. & Winkler, S. 2010: Schmidt-hammer exposure-Age Dating (SHD): application to early Holocene moraines and a reappraisal of the reliability of terrestrial cosmogenic-nuclide Dating (TCND) at Austanbotnbreen, Jotunheimen, Norway. Boreas, 10.1111/j.1502-3885.2010.00178.x. ISSN 0300-9483. Schmidt-hammer exposure-Age Dating (SHD) and terrestrial cosmogenic-nuclide Dating (TCND) are complementary techniques that can be used for mutual testing. SHD is low-cost but requires local control points of known Age and may be affected by local geological variation and other environmental factors that influence weathering rates. TCND is vulnerable to the occurrence of anomalous boulders, other geomorphological uncertainties and the effects of snow-shielding at high altitudes. Both techniques are sensitive to post-depositional disturbances if other than solid bedrock is sampled. SHD was applied to two moraine ridges beyond the Little Ice Age limit of Austanbotnbreen in the Hurrungane massif, southern Norway. Independent regional and experimental local Age-calibration curves were used to reappraise previous TCND results. Neither the two boulder surfaces nor their proximal bedrock surfaces could be differentiated statistically in terms of SHD exposure Ages or their mean R-values (±95% confidence intervals), which ranged from 40.73±1.72 to 43.34±0.69. The best of the independent regional-calibration curves produced SHD exposure Ages of 9413±723 and 9304±602 years, which are consistent with moraine formation early (c. 10.2 ka) and late (c. 9.7 ka) within the late-Preboreal Erdalen Event. The current precision of SHD, as reflected in 95% confidence intervals of ±500–900 years, enables rejection of a Finse Event (c. 8.2 ka) Age for either moraine. Results are consistent with a retracted Austanbotnbreen between the Erdalen Event and the Little Ice Age, and a modified model of Neoglaciation.
Edward Sisco - One of the best experts on this subject based on the ideXlab platform.
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strategies for potential Age Dating of fingerprints through the diffusion of sebum molecules on a nonporous surface analyzed using time of flight secondary ion mass spectrometry
Analytical Chemistry, 2015Co-Authors: Shin Muramoto, Edward SiscoAbstract:Age Dating of fingerprints could have a significant impact in forensic science, as it has the potential to facilitate the judicial process by assessing the relevance of a fingerprint found at a crime scene. However, no method currently exists that can reliably predict the Age of a latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (TOF-SIMS) was used to measure the diffusivity of saturated fatty acid molecules from a fingerprint on a silicon wafer. It was found that their diffusion from relatively fresh fingerprints (t ≤ 96 h) could be modeled using an error function, with diffusivities (mm2/h) that followed a power function when plotted against molecular weight. The equation x = 0.02t0.5 was obtained for palmitic acid that could be used to find its position in millimeters (where the concentration is 50% of its initial value or c0/2) as a function of time in hours. The results show that on a clean silicon substrate, the Age of a fingerprint (t ≤ 96 h) could reli...
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strategies for potential Age Dating of fingerprints through the diffusion of sebum molecules on a nonporous surface analyzed using time of flight secondary ion mass spectrometry
Analytical Chemistry, 2015Co-Authors: Shin Muramoto, Edward SiscoAbstract:Age Dating of fingerprints could have a significant impact in forensic science, as it has the potential to facilitate the judicial process by assessing the relevance of a fingerprint found at a crime scene. However, no method currently exists that can reliably predict the Age of a latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (TOF-SIMS) was used to measure the diffusivity of saturated fatty acid molecules from a fingerprint on a silicon wafer. It was found that their diffusion from relatively fresh fingerprints (t ≤ 96 h) could be modeled using an error function, with diffusivities (mm(2)/h) that followed a power function when plotted against molecular weight. The equation x = 0.02t(0.5) was obtained for palmitic acid that could be used to find its position in millimeters (where the concentration is 50% of its initial value or c0/2) as a function of time in hours. The results show that on a clean silicon substrate, the Age of a fingerprint (t ≤ 96 h) could reliably be obtained through the extent of diffusion of palmitic acid.
Mariejo Goupil - One of the best experts on this subject based on the ideXlab platform.
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asteroseismology for a la carte stellar Age Dating and weighing Age and mass of the corot exoplanet host hd 52265
Astronomy and Astrophysics, 2014Co-Authors: Y Lebreton, Mariejo GoupilAbstract:Context. In the context of the space missions CoRoT, Kepler, Gaia, TESS, and PLATO, precise and accurate stellar Ages, masses, and radii are of paramount importance. For instance, they are crucial for constraining scenarii of planetary formation and evolution. Aims. We aim at quantifying how detailed stellar modelling can improve the accuracy and precision on Age and mass of individual stars. To that end, we adopt a multifaceted approach where we carefully examine how the number of observational constraints as well as the uncertainties on observations and on model input physics affect the results of Age-Dating and weighing. Methods. We modelled in detail the exoplanet host-star HD 52265, a main-sequence, solar-like oscillator that CoRoT observed for four months. We considered different sets of observational constraints (Hertzsprung-Russell data, metallicity, various sets of seismic constraints). For each case, we determined the Age, mass, and properties of HD 52265 inferred from stellar models, and we quantified the impact of the model input physics and free parameters. We also compared model Ages with Ages derived by empirical methods or Hertzsprung-Russell diagram inversion. Results. For our case study HD 52265, our seismic analysis provides an Age A = 2.10−2.54 Gyr, a mass M = 1.14−1.32 M� ,a nd a radius R = 1.30−1.34 R� , which corresponds to Age, mass, and radius uncertainties of ∼10, ∼7, and ∼1.5 per cent, respectively. These uncertainties account for observational errors and current state-of-the-art stellar model uncertainties. Our seismic study also provides constraints on surface convection properties through the mixing-length, which we find to be 12−15 per cent lower than the solar value. On the other hand, because of helium-mass degeneracy, the initial helium abundance is determined modulo the mass value. Finally, we evaluate the seismic mass of the exoplanet to be Mp sini = 1.17−1.26 MJupiter, much more precise than what can be derived by Hertzsprung-Russell diagram inversion. Conclusions. We demonstrate that asteroseismology allows us to substantially improve the Age accuracy that can be achieved with other methods. We emphasize that the knowledge of the mean properties of stellar oscillations – such as the large frequency separation – is not enough to derive accurate Ages. We need precise individual frequencies to narrow the Age scatter that is a result of the model input physics uncertainties. Further progress is required to better constrain the physics at work in stars and the stars helium content. Our results emphasize the importance of precise classical stellar parameters and oscillation frequencies such as will be obtained by the Gaia and PLATO missions.
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asteroseismology for a la carte stellar Age Dating and weighing Age and mass of the corot exoplanet host hd 52265
arXiv: Solar and Stellar Astrophysics, 2014Co-Authors: Y Lebreton, Mariejo GoupilAbstract:In the context of CoRoT, Kepler, Gaia, TESS, and PLATO, precise and accurate stellar Ages, masses and radii are of paramount importance. They are crucial to constrain scenarii of planetary formation and evolution.We aim at quantifying how detailed stellar modeling improves the accuracy and precision on Age and mass of individual stars. We adopt a multifaceted approach where we examine how the number of observational constraints as well as the uncertainties on observations and on model input physics impact the Age-Dating and weighing. We modelled the exoplanet host-star HD52265, a MS, solar-like oscillator observed by CoRoT. We considered different sets of observational constraints (HR data, metallicity, seismic constraints). For each case, we determined the Age, mass, and properties of HD52265 inferred from models, and quantified the impact of the models inputs. Our seismic analysis provides an Age A=2.10-2.54 Gyr, a mass M=1.14-1.32 Msun, and a radius R=1.30-1.34 Rsun, which corresponds to uncertainties of 10, 7, and 1.5% respectively. Our seismic study provides constraints on surface convection, through the mixing-length found to be 12-15% smaller than the solar one. Because of helium-mass degeneracy, the initial He abundance is determined modulo the mass. The seismic mass of the exoplanet is found to be Mp sin i=1.17-1.26 MJup, much more precise than what can be derived by HR diagram inversion. We demonstrate that asteroseismology allows to improve the Age accuracy compared to other methods. We emphasize that the knowledge of the mean properties of oscillations -as the large frequency separation- is not enough for deriving accurate Ages. We need precise individual frequencies to narrow the Age scatter due to model uncertainties. This strengthen the case for precise classical stellar parameters and frequencies as will be obtained by Gaia and PLATO.
John A Matthews - One of the best experts on this subject based on the ideXlab platform.
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schmidt hammer exposure Ages from periglacial patterned ground sorted circles in jotunheimen norway and their interpretative problems
Geografiska Annaler Series A-physical Geography, 2016Co-Authors: Stefan Winkler, John A Matthews, Richard W Mourne, P WilsonAbstract:Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt‐hammer exposure‐Age Dating ...
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schmidt hammer exposure Age Dating shd application to early holocene moraines and a reappraisal of the reliability of terrestrial cosmogenic nuclide Dating tcnd at austanbotnbreen jotunheimen norway
Boreas, 2011Co-Authors: John A Matthews, Stefan WinklerAbstract:Matthews, J. A. & Winkler, S. 2010: Schmidt-hammer exposure-Age Dating (SHD): application to early Holocene moraines and a reappraisal of the reliability of terrestrial cosmogenic-nuclide Dating (TCND) at Austanbotnbreen, Jotunheimen, Norway. Boreas, 10.1111/j.1502-3885.2010.00178.x. ISSN 0300-9483. Schmidt-hammer exposure-Age Dating (SHD) and terrestrial cosmogenic-nuclide Dating (TCND) are complementary techniques that can be used for mutual testing. SHD is low-cost but requires local control points of known Age and may be affected by local geological variation and other environmental factors that influence weathering rates. TCND is vulnerable to the occurrence of anomalous boulders, other geomorphological uncertainties and the effects of snow-shielding at high altitudes. Both techniques are sensitive to post-depositional disturbances if other than solid bedrock is sampled. SHD was applied to two moraine ridges beyond the Little Ice Age limit of Austanbotnbreen in the Hurrungane massif, southern Norway. Independent regional and experimental local Age-calibration curves were used to reappraise previous TCND results. Neither the two boulder surfaces nor their proximal bedrock surfaces could be differentiated statistically in terms of SHD exposure Ages or their mean R-values (±95% confidence intervals), which ranged from 40.73±1.72 to 43.34±0.69. The best of the independent regional-calibration curves produced SHD exposure Ages of 9413±723 and 9304±602 years, which are consistent with moraine formation early (c. 10.2 ka) and late (c. 9.7 ka) within the late-Preboreal Erdalen Event. The current precision of SHD, as reflected in 95% confidence intervals of ±500–900 years, enables rejection of a Finse Event (c. 8.2 ka) Age for either moraine. Results are consistent with a retracted Austanbotnbreen between the Erdalen Event and the Little Ice Age, and a modified model of Neoglaciation.
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the schmidt hammer as a relative Age Dating tool and its potential for calibrated Age Dating in holocene glaciated environments
Quaternary Science Reviews, 2006Co-Authors: Richard A Shakesby, John A Matthews, Geraint OwenAbstract:The Schmidt hammer is a relatively cheap, portable, sturdy instrument with proven value over the last two decades or so in rapidly Dating coarse inorganic deposits of diverse origins. Early views were that its Dating role was limited to distinguishing recently exposed from much older. Typically, either a few sites of possibly different Ages or occasional older surfaces amongst many young sites were studied. More recently, calibration curves based on individual R-value means from small numbers (2–4) of sites of known Ages have been used to estimate the Ages of undated sites. We present Schmidt hammer rebound (R–) values from 28 ‘Little Ice Age’ (and younger), 23 Preboreal and 7 Younger Dryas glaciated surfaces in southern Norway in order, first, to test rigorously the robustness of the instrument as a relative-Age Dating tool. Despite being obtained from different surfaces (moraines, glaciofluvial deposits and bedrock) and varied metamorphic lithologies, the R-value overall means and 95% confidence intervals for the ‘Little Ice Age’, Preboreal and Younger Dryas Age categories (respectively, 60.0±1.6, 41.6±1.4 and 34.2±2.0) are statistically significantly different. Only two outlying sites in the two younger Age categories have overlapping confidence intervals, demonstrating remarkable robustness in differentiating early- and late-Holocene surfaces. The distinction between Preboreal and Younger Dryas sites (with terminal dates <2000 years apart) is less clear but still statistically significant, though possibly partly because of enhanced weathering conditions at the predominantly well vegetated Younger Dryas sites. Second, we examine the feasibility and desirability of controlling non-Age-related factors, including some previously considered critical (instrument wear, operator bias, initial rock surface texture), which emerge either as less important than previously argued or as relatively unimportant, together with others previously unreported (e.g. long-term changes in lichen, soil, snow and vegetation covers). Third, we investigate the potential for calibrated-Age Dating by applying exploratory, linear rates of R-value decline to selected combinations of sites. The results suggest that error limits of ca ±700 to ±1600 years should be achievable over the Holocene timescale. This improved Dating capability, however, will require adequate numbers of site means not only for each Age category used to define these curves but also for each set of test surfaces of the same Ages. Recommendations are made for a suitable sampling protocol for developing further the Schmidt hammer as a calibrated-Age Dating tool.