Astronomy and Astrophysics – Astronomy
Scientific paper
Apr 1992
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992rmxaa..24...27c&link_type=abstract
Revista Mexicana de Astronomia y Astrofisica, 24, 27
Astronomy and Astrophysics
Astronomy
74
Scientific paper
RESUMEN Hemos calculado el flujo emergente de sistemas compuestos de una estrella j6ven rodeada de un disco de acrecimiento fisicamente delgado, 6pticamente grueso, sujeto a irradiaci6j por la estrella. Hemos encontrado lo siguiente: (1) el continuo emergente es mas bajo que el calculado con la suposici6n que toda la energfa se deposita ei el fondo de la atm6sfera en cada anillo; por lo tanto, los discos deben abrirse mas 0 tener tasas de acrecimiento de masa ma's altas de lo que se pensaba anteriormente; (2) la irradiaci6n domina a grandes radios en el disco, produciendo una inversi6n de en la del . El radio en el disco donde la irradiaci6n se hace ma's que el viscoso aunienta cuando la tasa de acrecimiento aumetita o la temperatura efbcti' a de la estrella ; (3) la iiitensidad en absorci6n de las bandas de CO, H2O, TiO y de silicato eii 10 in es una medida de la tasa de acrecimiento de masa; (4) los discos de acrecimiento 6pticamente gruesos pueden reproducir 40% de los colores infrarrojos cercanos de estrellas T Tauri. Los discos con grandes pendientes y grandes , Rmaz < 100 UA, pueden explicar el exceso infrarrojo lejano, pero todavia no pueden explicarse los colores de 20% de los objetos; (5) este estudio los parametros del disco pueden determinarse a partir de los siguientes observables: M puede ser deterniinado a partir de las bandas ilares de H2O, CO y TiO; la del disco por el silica to, Si se M; contas, el radio maximo del disco a partir del flujo a A > 1 . Se requiere espectrofotoinetria de alta resoluci6n para probar estas predicciones. ABSTRACT è have calcuIated the eniergent flux for systems composed of a young star a steady, , optically accretion disk subject to irradiation fiom the star. Ve have fouiid following: (I) emergent continuum flux is lower calculated that all the stellar eiiergy is deposited at the bottom of the atmosphere at each of disk; thus, disks have larger flaring, or larger accretion rates than previously ; (2) irradiation determines heating at large radii, a tei inversioii in the disk . The disk radius where the heating to irradiatioi becomes more important than viscous heating increases when the mass accretion rate increases and the stellar effective temperature decreases; (3) the ahsorptioi of the CO, 1-120, O bands, of the silicate feature is a measure of the mass accretion rate Af; (4) optically thick accretion disks can reproduce 40% of the -infrared color observations for T Tauri stars. Large degrees of flaring and large disk sizes, Rmaz < 100 AU can explaiii objects with fairly large -infrared excess, still 20% of the objects ot be understood with the present models; (5) this suggests that disk parameters can be with the following observables. M can be determined from the molecular bands of H2O, CO, and TiO; the flaring of the disk can be determined from the silicate feature, once M is known; and with these, the maximum adius of the disk can be deteimined from the flux at A> 10 m. High resolution infrared spectrophotometric data are required to test these predictions. Kcy : DISKS - INFRARED SOURCES - STARS-
Calvet Nuria
D'Alessio Paola
Magris Gladis C.
Patino Alberto
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