HIP 114328: a new refractory-poor and Li-poor solar twin

Autor(es)

Melendez, Jorge ; Schirbel, Lucas ; Monroe, TalaWanda R. ; Yong, David ; Ramirez, Ivan ; Asplund, Martin

• Tipo de documento: Artigo Científico
• Fonte: ASTRONOMY & ASTROPHYSICS; v. 567, p. 5-pg., 2014-07-01.

Resumo

Context. The standard solar model fails to predict the very low lithium abundance in the Sun, which is much lower than the proto-solar nebula (as measured in meteorites), This Li problem has been debated for decades, and it has been ascribed either to planet formation or to secular stellar depletion due to additional mixing below the convection zone, either during the pre main sequence and thus possibly linked to planet formation, or additionally on secular time-scales during the main sequence. In order to test the evolution of Li, it is important to find solar twins in a range of ages. i.e., stars with about one solar mass and metallicity but in different evolutionary stages. Furthermore. the study of stars similar to the Sun is relevant in relation to the signature of terrestrial planet formation around the Sun, and for anchoring photometric and spectroscopic stellar parameter scales. Aims. We aim to identify and analyse solar twins using high quality spectra, in order to study Li depletion in the Sun and the possible relation between chemical abundance anomalies and planet formation. Methods. We acquired high resolution (R similar to 110 000), high SIN (similar to 300) ESO/VLT UVES spectra of several solar twin candidates and the Sun (as reflected from the asteroid Juno). Among the solar twin candidates we identify HIP 114328 as a solar twin and perform a differential line-by-line abundance analysis of this star relative to the Sun. Results. HIP 114328 has stellar parameters T-eff = 5785 +/- 10 K. log g = 4.38 +/- 0.03, [Fe/H] = -0.022 +/- 0.009, and a rnicroturbulent velocity 0.05 +/- 0.03 km s(-1) higher than solar. The differential analysis shows that this star is chemically very similar to the Sun. The refractory elements seem slightly more depleted than in the Sun meaning that HIP 114328 may be as likely to form terrestrial planets as the Sun. HIP 114328 is about 2 Gyr older than the Sun, and is thus the second oldest solar twin analysed at high precision. It has a Li abundance of A(Li)(NLTE) less than or similar to 0,46, which Is about 4 times lower than in the Sun (A(Li)(NLTE) = 1.07 dex), but close to the oldest solar twin known, HIP 102152. Conclusions. Based on the lower abundances of refractory elements when compared to other solar twins, HIP 114328 seems an excellent candidate to host rocky planet. The low Li abundance of this star is consistent with its old age and fits very well the emerging Li-age relation among solar twins of different ages. (AU)

• Processo FAPESP: 12/24392-2 - Espectroscopia de alta precisão: impacto no estudo de planetas, estrelas, a galáxia e cosmologia
• Beneficiário: Jorge Luis Melendez Moreno
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/25008-4 - Composição química em estrelas de tipo solar
• Beneficiário: Lucas Alexandre Schirbel
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 10/19810-4 - Investigando a formação de planetas através de abundâncias químicas de estrelas de tipo solar
• Beneficiário: TalaWanda Rose Monroe
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado