Effect of local treatments of convection upon the solar p-mode excitation rates

We compute, for several solar models, the rates P at which the solar radial p modes are expected to be excited. The solar models are computed with two different local treatments of convection : the classical mixing-length theory (MLT hereafter) and Canuto, Goldmann and Mazzitelli(1996, CGM hereafter)'s formulation. For one set of solar models (EMLT and ECGM models), the atmosphere is gray and assumes Eddington's approximation. For a second set of models (KMLT and KCGM models), the atmosphere is built using a T(tau) law which has been obtained from a Kurucz's model atmosphere computed with the same local treatment of convection. The mixing-length parameter in the model atmosphere is chosen so as to provide a good agreement between synthetic and observed Balmer line profiles, while the mixing-length parameter in the interior model is calibrated so that the model reproduces the solar radius at solar age. For the MLT treatment, the rates P do depend significantly on the properties of the atmosphere. On the other hand, for the CGM treatment, differences in P between the ECGM and the KCGM models are very small compared to the error bars attached to the seismic measurements. The excitation rates P for modes from the EMLT model are significantly under-estimated compared with the solar seismic constraints. The KMLT model results in intermediate values for P and shows also an important discontinuity in the temperature gradient and the convective velocity. On the other hand, the KCGM model and the ECGM model yield values for P closer to the seismic data than the EMLT and KMLT models. We conclude that the solar p-mode excitation rates provide valuable constraints and according to the present investigation cleary favor the CGM treatment with respect to the MLT.Comment: 4 pages, 3 figures, proceedings of the SOHO14/GONG 2004 workshop "Helio- and Asteroseismology: Towards a Golden Future" from July 12-16 2004 at New Haven CT (USA

Influence of local treatments of convection upon solar p mode excitation rates

We compute the rates P at which acoustic energy is injected into the solar radial p modes for several solar models. The solar models are computed with two different local treatments of convection: the classical mixing-length theory (MLT hereafter) and Canuto et al (1996)'s formulation (CGM hereafter). Among the models investigated here, our best models reproduce both the solar radius and the solar luminosity at solar age and the observed Balmer line profiles. For the MLT treatment, the rates P do depend significantly on the properties of the atmosphere whereas for the CGM's treatment the dependence of P on the properties of the atmosphere is found smaller than the error bars attached to the seismic measurements. The excitation rates P for modes associated with the MLT models are significantly underestimated compared with the solar seismic constraints. The CGM models yield values for P closer to the seismic data than the MLT models. We conclude that the solar p-mode excitation rates provide valuable constraints and according to the present investigation clearly favor the CGM treatment with respect to the MLT, although neither of them yields values of P as close to the observations as recently found for 3D numerical simulations.Comment: 11 pages, 7 figures, accepted for publication in Astronomy & Astrophysic

Seismic diagnostics for transport of angular momentum in stars 2. Interpreting observed rotational splittings of slowly-rotating red giant stars

Asteroseismology with the space-borne missions CoRoT and Kepler provides a powerful mean of testing the modeling of transport processes in stars. Rotational splittings are currently measured for a large number of red giant stars and can provide stringent constraints on the rotation profiles. The aim of this paper is to obtain a theoretical framework for understanding the properties of the observed rotational splittings of red giant stars with slowly rotating cores. This allows us to establish appropriate seismic diagnostics for rotation of these evolved stars. Rotational splittings for stochastically excited dipolar modes are computed adopting a first-order perturbative approach for two $1.3 M_\odot$ benchmark models assuming slowly rotating cores. For red giant stars with slowly rotating cores, we show that the variation of the rotational splittings of $\ell=1$ modes with frequency depends only on the large frequency separation, the g-mode period spacing, and the ratio of the average envelope to core rotation rates (${\cal R}$). This leds us to propose a way to infer directly ${\cal R}$ from the observations. This method is validated using the Kepler red giant star KIC 5356201. Finally, we provide a theoretical support for the use of a Lorentzian profile to measure the observed splittings for red giant stars.Comment: 15 pages, 15 figures, accepted for publication in A&

Principios e interés de los test Bondad de Ajuste (GOF) para los modelos de captura–recaptura multiestado

Optimal goodness–of–fit procedures for multistate models are new. Drawing a parallel with the corresponding single–state procedures, we present their singularities and show how the overall test can be decomposed into interpretable components. All theoretical developments are illustrated with an application to the now classical study of movements of Canada geese between wintering sites. Through this application, we exemplify how the interpretable components give insight into the data, leading eventually to the choice of an appropriate general model but also sometimes to the invalidation of the multistate models as a whole. The method for computing a corrective overdispersion factor is then mentioned. We also take the opportunity to try to demystify some statistical notions like that of Minimal Sufficient Statistics by introducing them intuitively. We conclude that these tests should be considered an important part of the analysis itself, contributing in ways that the parametric modelling cannot always do to the understanding of the data.Los procedimientos óptimos de bondad de ajuste, aplicados a los modelos multiestado, son nuevos. Trazando un paralelismo con los correspondientes procesos de uniestado, presentamos sus articularidades y mostramos como el test general puede descomponerse en componentes susceptibles de ser interpretados. Todos los desarrollos teóricos están ilustrados con una aplicación del ya clásico estudio de los desplazamientos de la barnacla canadiense entre sus lugares de invernada. Mediante esta aplicación, presentamos un ejemplo de cómo los componentes susceptibles de ser interpretados nos proporcionan una idea de los datos que nos pueden llevar a la elección de un modelo general apropiado, pero también a veces a la invalidación de los modelos de multiestados en su conjunto. Se menciona entonces el método para calcular un factor de corrección de la sobredispersión. Aprovechamos esta ocasión para intentar también desmitificar algunas nociones estadísticas, como las Estadísticas Suficientes Mínimas, introduciéndolas intuitivamente. La conclusión es que estas pruebas deberían considerarse una parte importante del propio análisis, contribuyendo a la comprensión de los datos, de un modo que el modelaje paramétrico no siempre consigue

M–SURGE: new software specifically designed for multistate capture–recapture models

M–SURGE, al igual que su compañero, el programa U–CARE, se ha escrito con el propósito específico de manejar modelos multiestado de captura–recaptura, lo que a su vez permite mitigar las dificultades inherentes a los mismos (especificación de los modelos, calidad de la convergencia, flexibilidad de parametrización, evaluación del ajuste). En su terreno, M–SURGE abarca una gama de modelos más extensa que un programa general, como el MARK (White & Burnham, 1999), al tiempo que resulta más accesible para el usuario que el MS–SURVIV (Hines, 1994). De entre las principales características del M–SURGE, cabe destacar una amplia gama de modelos y varias parametrizaciones: (1) M–SURGE abarca los modelos condicionales con probabilidad de recaptura según el estado actual (modelos tipo Arnason–Schwarz), y según el estado actual y previo (modelos tipo Jolly–movement). En ambos casos, es posible examinar los efectos dependientes de la edad y/o del tiempo, así como grupos múltiples. (2) Las probabilidades combinadas de supervivencia–transición pueden representarse como tales, o descomponerse en probabilidades de transición y supervivencia. (3) Por lo que respecta a las probabilidades de transición con el mismo estado de partida, el usuario puede elegir libremente la probabilidad que deberá calcularse por sustracción. Además de ser un programa muy accesible para el usuario, también debe subrayarse la facilidad con que permite construir modelos constreñidos utilizando un lenguaje interpretado denominado GEMACO. En este estudio desarrollamos y presentamos varios tipos de modelos multiestado.M–SURGE (along with its companion program U–CARE) has been written specifically to handle multistate capture–recapture models and to alleviate their inherent difficulties (model specification, quality of convergence, flexibility of parameterization, assessment of fit). In its domain, M–SURGE covers a broader range of models than a general program like MARK (White & Burnham, 1999), while being more user–friendly than MS–SURVIV (Hines, 1994). Among the main features of M–SURGE is a wide class of models and a variety of parameterizations: (1) M–SURGE covers conditional models with probability of recapture depending on the current state (Arnason–Schwarz type models) as well as on the current and previous state (Jolly–movement type models). In both cases, age and/or time–dependence and multiple groups can be considered. (2) Combined survival–transition probabilities can be represented as such or decomposed into transition and survival probabilities. (3) Among the transition probabilities with the same state of departure, the one to be computed by subtraction can be freely picked by the user. User–friendliness is enhanced by the easiness with which constrained models are built, using an interpreted language called GEMACO. Examples of various types of multistate models are developed and presented

Thorough analysis of input physics in CESAM and CLES codes

This contribution is not about the quality of the agreement between stellar models computed by CESAM and CLES codes, but more interesting, on what ESTA-Task~1 run has taught us about these codes and about the input physics they use. We also quantify the effects of different implementations of the same physics on the seismic properties of the stellar models, that in fact is the main aim of ESTA experiments.Comment: 11 pages, 12 fig. Accepted for publication in ApSS CoRoT/ESTA Volu