Excesso no infravermelho e a detecção de discos circunstelares em estrelas da pós-sequência principal

Abstract

In this work, we look for circumstellar disks around red giants and white dwarf stars of the main post-sequence, through the analysis of the infrared excess (IR) from the spectral energy distributions (SED), and the visual inspection of the images in the photometric bands from the WISE satellite for each estar. Our sample of the red giant stars is made up of 6676 stars from the Pinsonneault et al. (2018) catalog and 360 fast rotating red giants from the Ceillier et al. (2017) catalog. For the red giants we found 5 stars with an excess of infrared indicative of a circumstellar disc and we estimated the parameters of the discs such as internal radius, temperature and disc mass. The sample of the white dwarf stars was taken from the catalog of Gentile Fusillo et al. (2017), composed of 12,359 objects. Of these, 220 stars have flows from 2MASS (Cutri et al. 2003) in the bands 1:24, 1:63 and 2:16 m (J, H and K, respectively) and 3:4, 4:6, 12 and 22 m bands (W1, W2, W3 and W4, respectively) from WISE satellite (Cutri 2013). Only 41 of these stars had significance of the infrared excess 3:0 as Ribas et al. (2012) and 31 objects showed excess in the bands W1 and W2 according to their SEDs. We studied for these stars the behavior of the infrared excess with respect to age. Finally, 3 stars were selected with a possible excess from the visual inspection in these bands. For the final sample of 3 white dwarfs, we calculated the physical parameters of the disc. For this sample, these parameters are in the following range: temperature (1; 000 T 1800K), brightness fraction (1:25 10 4 L I R / L 1:08 10 3 ), internal radius (0:000694 Rd 0:099733 UA) and mass (1:81 10 11 Md 4:84 10 7 M).