Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

Another forbidden solar oxygen abundance: the [OI] 5577 Å line

J. Meléndez, M. Asplund

Abstract
Context. Recent works with improved model atmospheres, line formation, atomic and  molecular data, and detailed treatment of blends, have resulted in a significant  downward revision of the solar oxygen abundance.
Aims. Considering the importance of the Sun as an astrophysical standard and the  current conflict of standard solar models using the new solar abundances with  helioseismological observations we have performed a new study of the solar oxygen  abundance based on the forbidden [OI] line at 5577.34 Å, not previously considered.
Methods.
High-resolution (R > 500 000), high signal-to-noise (S/N > 1000) solar  spectra of the [OI] 5577.34 Å line have been analyzed employing both three dimensional (3D) and a variety of 1D (spatially and temporally averaged 3D, Holweger  & Müller, MARCS and Kurucz models with and without convective overshooting) model atmospheres.
Results. The oxygen abundance obtained from the [OI] 5577.3 Å forbidden line is  almost insensitive to the input model atmosphere and has a mean value of log εo =  8.71 ± 0.02 (σ from using the different model atmospheres). The total error (0.07  dex) is dominated by uncertainties in the log gf value (0.03 dex), apparent line variation (0.04 dex) and uncertainties in the continuum and line positions (0.05 dex).
Conclusions. The here derived oxygen abundance is close to the 3D-based estimates  from the two other [OI] lines at 6300 and 6363 Å, the permitted OI lines and vibrational and rotational OH transitions in the infrared. Our study thus supports a low  solar oxygen abundance (log εo ≈ 8.7), independent of the adopted model  atmosphere.

Astronomy and Astrophysics
Volume 490, Page 817
November 2008

>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website