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R A Garcia - One of the best experts on this subject based on the ideXlab platform.

  • granulation in red giants observations by the kepler mission and three dimensional convection simulations
    The Astrophysical Journal, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, R A Garcia
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection Models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, νmax) as well as with stellar Parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffν–0.89 max and P granν–1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.

  • granulation in red giants observations by the kepler mission and 3d convection simulations
    arXiv: Solar and Stellar Astrophysics, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, Daniel Hube, A Jimenez, R A Garcia, T R Edding
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones and more extended atmospheres than the Sun, we cannot a priori assume that granulation in red giants is a scaled version of solar granulation. Until now, neither observations nor 1D analytical convection Models could put constraints on granulation in red giants. However, thanks to asteroseismology, this study can now be performed. The resulting Parameters yield physical information about the granulation. We analyze \sim1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (time scale tau_gran and power P_gran). We also introduce a new time scale, tau_eff, which takes into account that different slopes are used in the Harvey functions. We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, nu_max) as well as with stellar Parameters (mass, radius, surface gravity (log g) and effective temperature (T_eff)). We show that tau_eff nu_max^{-0.89} and P_gran nu_max^{-1.90}, which is consistent with the theoretical predictions. We find that the granulation time scales of stars that belong to the red clump have similar values while the time scales of stars in the red-giant branch are spread in a wider range. Finally, we show that realistic 3D simulations of the surface convection in stars, spanning the (T_eff, log g)-range of our sample of red giants, match the Kepler observations well in terms of trends.

Saskia Hekke - One of the best experts on this subject based on the ideXlab platform.

  • granulation in red giants observations by the kepler mission and three dimensional convection simulations
    The Astrophysical Journal, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, R A Garcia
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection Models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, νmax) as well as with stellar Parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffν–0.89 max and P granν–1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.

  • granulation in red giants observations by the kepler mission and 3d convection simulations
    arXiv: Solar and Stellar Astrophysics, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, Daniel Hube, A Jimenez, R A Garcia, T R Edding
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones and more extended atmospheres than the Sun, we cannot a priori assume that granulation in red giants is a scaled version of solar granulation. Until now, neither observations nor 1D analytical convection Models could put constraints on granulation in red giants. However, thanks to asteroseismology, this study can now be performed. The resulting Parameters yield physical information about the granulation. We analyze \sim1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (time scale tau_gran and power P_gran). We also introduce a new time scale, tau_eff, which takes into account that different slopes are used in the Harvey functions. We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, nu_max) as well as with stellar Parameters (mass, radius, surface gravity (log g) and effective temperature (T_eff)). We show that tau_eff nu_max^{-0.89} and P_gran nu_max^{-1.90}, which is consistent with the theoretical predictions. We find that the granulation time scales of stars that belong to the red clump have similar values while the time scales of stars in the red-giant branch are spread in a wider range. Finally, we show that realistic 3D simulations of the surface convection in stars, spanning the (T_eff, log g)-range of our sample of red giants, match the Kepler observations well in terms of trends.

Julio Allo - One of the best experts on this subject based on the ideXlab platform.

  • granulation in red giants observations by the kepler mission and three dimensional convection simulations
    The Astrophysical Journal, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, R A Garcia
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection Models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, νmax) as well as with stellar Parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffν–0.89 max and P granν–1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.

  • granulation in red giants observations by the kepler mission and 3d convection simulations
    arXiv: Solar and Stellar Astrophysics, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, Daniel Hube, A Jimenez, R A Garcia, T R Edding
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones and more extended atmospheres than the Sun, we cannot a priori assume that granulation in red giants is a scaled version of solar granulation. Until now, neither observations nor 1D analytical convection Models could put constraints on granulation in red giants. However, thanks to asteroseismology, this study can now be performed. The resulting Parameters yield physical information about the granulation. We analyze \sim1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (time scale tau_gran and power P_gran). We also introduce a new time scale, tau_eff, which takes into account that different slopes are used in the Harvey functions. We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, nu_max) as well as with stellar Parameters (mass, radius, surface gravity (log g) and effective temperature (T_eff)). We show that tau_eff nu_max^{-0.89} and P_gran nu_max^{-1.90}, which is consistent with the theoretical predictions. We find that the granulation time scales of stars that belong to the red clump have similar values while the time scales of stars in the red-giant branch are spread in a wider range. Finally, we show that realistic 3D simulations of the surface convection in stars, spanning the (T_eff, log g)-range of our sample of red giants, match the Kepler observations well in terms of trends.

T Kallinge - One of the best experts on this subject based on the ideXlab platform.

  • granulation in red giants observations by the kepler mission and three dimensional convection simulations
    The Astrophysical Journal, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, R A Garcia
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma rising to the photosphere where it cools down and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones than the Sun, we cannot a priori assume that their granulation is a scaled version of solar granulation. Until now, neither observations nor one-dimensional analytical convection Models could put constraints on granulation in red giants. With asteroseismology, this study can now be performed. We analyze ~1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (timescale τgran and power P gran). We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, νmax) as well as with stellar Parameters (mass, radius, surface gravity (log g), and effective temperature (T eff)). We show that τeffν–0.89 max and P granν–1.90 max, which is consistent with the theoretical predictions. We find that the granulation timescales of stars that belong to the red clump have similar values while the timescales of stars in the red giant branch are spread in a wider range. Finally, we show that realistic three-dimensional simulations of the surface convection in stars, spanning the (T eff, log g) range of our sample of red giants, match the Kepler observations well in terms of trends.

  • granulation in red giants observations by the kepler mission and 3d convection simulations
    arXiv: Solar and Stellar Astrophysics, 2011
    Co-Authors: S Mathu, Saskia Hekke, R Trampedach, Julio Allo, T Kallinge, Derek L Uzasi, Daniel Hube, A Jimenez, R A Garcia, T R Edding
    Abstract:

    The granulation pattern that we observe on the surface of the Sun is due to hot plasma from the interior rising to the photosphere where it cools down, and descends back into the interior at the edges of granules. This is the visible manifestation of convection taking place in the outer part of the solar convection zone. Because red giants have deeper convection zones and more extended atmospheres than the Sun, we cannot a priori assume that granulation in red giants is a scaled version of solar granulation. Until now, neither observations nor 1D analytical convection Models could put constraints on granulation in red giants. However, thanks to asteroseismology, this study can now be performed. The resulting Parameters yield physical information about the granulation. We analyze \sim1000 red giants that have been observed by Kepler during 13 months. We fit the power spectra with Harvey-like profiles to retrieve the characteristics of the granulation (time scale tau_gran and power P_gran). We also introduce a new time scale, tau_eff, which takes into account that different slopes are used in the Harvey functions. We search for a correlation between these Parameters and the global acoustic-Mode Parameter (the position of maximum power, nu_max) as well as with stellar Parameters (mass, radius, surface gravity (log g) and effective temperature (T_eff)). We show that tau_eff nu_max^{-0.89} and P_gran nu_max^{-1.90}, which is consistent with the theoretical predictions. We find that the granulation time scales of stars that belong to the red clump have similar values while the time scales of stars in the red-giant branch are spread in a wider range. Finally, we show that realistic 3D simulations of the surface convection in stars, spanning the (T_eff, log g)-range of our sample of red giants, match the Kepler observations well in terms of trends.

Pengfei Guan - One of the best experts on this subject based on the ideXlab platform.

  • soft Mode Parameter as an indicator for the activation energy spectra in metallic glass
    Journal of Physical Chemistry Letters, 2020
    Co-Authors: Shan Zhang, Chaoyi Liu, Yue Fan, Yong Yang, Pengfei Guan
    Abstract:

    The activation energy (EA) spectra of the potential energy landscape (PEL) provide a convenient perspective for interpreting complex phenomena in amorphous materials; however, the link between the EA spectra and other physical properties in metallic glasses is still mysterious. By systematically probing the EA spectra for numerous metallic glass samples with distinct local geometric ordering, which correspond to broad processing histories, we found that the shear moduli of the samples are strongly correlated with the arithmetic mean of the EA spectra rather than with the local geometrical ordering. Furthermore, we studied the correlation of the obtained EA spectra and various well-established physical Parameters. The outcome of our research clearly demonstrates that the soft-Mode Parameter Ψ and the EA spectrum are correlated; therefore, this could be a good indicator of metallic glass properties and sheds important light on the structure-property relationship in metallic glass through the medium of the PEL.