S$\mathsf{^4}$N: A spectroscopic survey of stars in the solar neighborhood

Abstract

Abstract. We report the results of a high-resolution spectroscopic survey of all the stars more luminous than M V = 6.5 mag within 14.5 pc from the Sun. The Hipparcos catalog's completeness limits guarantee that our survey is comprehensive and free from some of the selection effects in other samples of nearby stars. The resulting spectroscopic database, which we have made publicly available, includes spectra for 118 stars obtained with a resolving power of R 50 000, continuous spectral coverage between ∼362−921 nm, and typical signal-to-noise ratios in the range 150−600. We derive stellar parameters and perform a preliminary abundance and kinematic analysis of the F-G-K stars in the sample. The inferred metallicity ([Fe/H]) distribution is centered at about −0.1 dex, and shows a standard deviation of 0.2 dex. A comparison with larger samples of Hipparcos stars, some of which have been part of previous abundance studies, suggests that our limited sample is representative of a larger volume of the local thin disk. We identify a number of metal-rich K-type stars which appear to be very old, confirming the claims for the existence of such stars in the solar neighborhood. With atmospheric effective temperatures and gravities derived independently of the spectra, we find that our classical LTE model-atmosphere analysis of metal-rich (and mainly K-type) stars provides discrepant abundances from neutral and ionized lines of several metals. This ionization imbalance could be a sign of departures from LTE or inhomogeneous structure, which are ignored in the interpretation of the spectra. Alternatively, but seemingly unlikely, the mismatch could be explained by systematic errors in the scale of effective temperatures. Based on transitions of majority species, we discuss abundances of 16 chemical elements. In agreement with earlier studies we find that the abundance ratios to iron of Si, Sc, Ti, Co, and Zn become smaller as the iron abundance increases until approaching the solar values, but the trends reverse for higher iron abundances. At any given metallicity, stars with a low galactic rotational velocity tend to have high abundances of Mg, Si, Ca, Sc, Ti, Co, Zn, and Eu, but low abundances of Ba, Ce, and Nd. The Sun appears deficient by roughly 0.1 dex in O, Si, Ca, Sc, Ti, Y, Ce, Nd, and Eu, compared to its immediate neighbors with similar iron abundances.

The radius and other fundamental parameters of the F9 V star β Virginis

“…The new value for the effective temperature can be compared with the previous estimates listed in Table 3. There is an excellent agreement with the line‐depth ratio determination by Kovtyukh et al (2003) and the determinations by Chen et al (2001) and Allende Prieto et al (2004) from the Strömgren photometry using the calibrations by Alonso, Arribas & Martinez‐Roger (1996) and Allende Prieto & Lambert (1999). The methods are completely independent, with only the new value presented here being based on a direct measurement of the angular diameter of the star.…”

“… Source references: (1) Thévenin, Vauclair & Vauclair (1986); (2) Balachandran (1990); (3) Edvardsson et al (1993); (4) di Benedetto (1998); (5) Blackwell & Lynas‐Gray (1998); (6) Malagnini et al (2000); (7) Chen et al (2001); (8) Gray, Graham & Hoyt (2001); (9) Kovtyukh et al (2003); (10) Morel & Micela (2004) and (11) Allende Prieto et al (2004). …”

A SPECTROSCOPIC ANALYSIS OF THE K0 III BINARYϵCYGNI

“…Conceptually this amounts to neglecting rotational broadening and assuming an isotropic Gaussian velocity distribution for the macroturbulence, even though we know rotational broadening does exist and macroturbulence is not isotropic. In other cases, a quadratic combination of v sin i and RT z is assumed even though this process is only appropriate for isotropic Gaussians (e.g., Benz & Mayor 1984;Melo et al 2001;Allende Prieto et al 2004;Hekker & Meléndez 2007;Massarotti et al 2008;Takeda et al 2008). The fact that when RT z is comparable to v sin i, the resultant disk integration is close to Gaussian (e.g., Gray 1978Gray , 2005b) is a temptation, and rather passable fits to observed profiles can be obtained with Gaussian blurring.…”

The STABLE K0 GIANT STAR Β GEM

“…Other determinations include: log g = 2.685 ± 0.091 (Allende Prieto et al 2004), 3.15 (Hekker & Meléndez 2007), 3.13 (Luck & Heiter 2007), 2.9 (Massarotti et al 2008), 2.84 (Takeda et al 2008), and 2.73 and 2.84 (Lee et al 2011). The effective temperature has been measured in several contexts with values ranging from 4666 K (Allende Prieto et al 2004) to 4998 (Luck & Heiter 2007). I will use here a midrange value of 4842 K from Gray & Brown (2001) based on Taylor (1999), which also turns out to be the mean of the values listed in the SIMBAD database.…”