Poster Abstracts

Name/Affiliation:  Luan Ghezzi (Harvard-Smithsonian CfA)

Title:  On the Spectroscopic Properties of the Retired A Star HD 185351

Doppler-based planet surveys have shown that, besides metallicity, the planet occurrence is also correlated with stellar mass, increasing from M to F-A spectral types. However, it has recently been argued that the subgiants (which represent A stars after they evolve off the main sequence) may not be as massive as suggested initially, which would significantly change the correlation found. To start investigating this claim, we have studied the subgiant star HD 185351, which has precisely measured physical properties based on asteroseismology and interferometry. An independent spectroscopic differential analysis based on excitation and ionization balance of iron lines yielded the atmospheric parameters Teff = 5035 +- 29 K, log g = 3.30 +- 0.08 and [Fe/H] = 0.10 +- 0.04. These were used in conjunction with the PARSEC stellar evolutionary tracks to infer a mass M = 1.77 +- 0.04 Msun, which agrees well with the previous estimates. Lithium abundance was also estimated from spectral synthesis (A(Li) = 0.93 +- 0.30) and, together with Teff and [Fe/H], allowed to determine a mass M = 2.0 [+0.1 -0.3] Msun, which is independent of the star's parallax and surface gravity. Although a variation of up to ~0.4 Msun can be observed between the different measurements, all values are higher than 1.6 Msun, which supports the correlation between planet occurrence and stellar masses.