Astronomy and Astrophysics, volume 621A, 58-58 (2019/1-1)
Fe I in the β Pictoris circumstellar gas disk. II. Time variations in the circumstellar iron gas.
KIEFER F., VIDAL-MADJAR A., LECAVELIER DES ETANGS A., BOURRIER V., EHRENREICH D., FERLET R., HEBRARD G. and WILSON P.A.
Abstract (from CDS):
The young planetary system β Pictoris is surrounded by a debris disk of dust and gas. The gas source of this disk could be exocomets (or "falling and evaporating bodies", FEBs), which produce refractory elements (Mg, Ca, Fe) through sublimation of dust grains at several tens of stellar radii. Nearly 1700 high resolution spectra of β Pictoris were obtained between 2003 and 2017 using the HARPS spectrograph. In Paper I (Vidal-Madjar et al., 2017A&A...607A..25V
), we showed that a high signal to noise ratio allows the detection of many weak FeI lines in more than ten excited levels, and we derived the physical characteristics of the iron gas in the disk. The measured temperature of the gas (∼1300K) suggests that it is produced by evaporation of grains at about 0.3au (38R*) from the star. Here, we describe the yearly variations of the column densities of all FeI components (from both ground and excited levels). The drop in the FeI ground level column density after 2011 coincides with a drop in FeI excited levels column density, as well as in the CaII doublet and a ground level CaI line at the same epoch. All drops are compatible with photoionisation-recombination equilibrium and β Pic like relative abundances, in a medium at 1300K and at 0.3au from β Pictoris. Interestingly, this warm medium does not correlate with the numerous exocomets in the circumstellar environnement of this young star.
© ESO 2019
stars: individual: β Pictoris - circumstellar matter - comets: general -K techniques: spectroscopic
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