Chemical abundance analysis of the open clusters Berkeley 32, NGC 752, Hyades, and Praesepe

Abstract

Context. Open clusters are ideal test particles for studying the chemical evolution of the Galactic disc. However, the number and accuracy of existing high-resolution abundance determinations, not only of [Fe/H], but also of other key elements, remains largely insufficient. Aims. We attempt to increase the number of Galactic open clusters that have high quality abundance determinations, and to gather all the literature determinations published so far. Methods. Using high-resolution (R ∼ 30 000), high-quality (S /N ≥ 60 per pixel), we obtained spectra for twelve stars in four open clusters with the fibre spectrograph FOCES, at the 2.2 Calar Alto Telescope in Spain. We employ a classical equivalent-width analysis to obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg, Na, Nd, Ni, Sc, Si, Ti, V, and Y. We derived oxygen abundances by means of spectral synthesis of the 6300 Å forbidden line. Results. We provide the first determination of abundance ratios other than Fe for NGC 752 giants, and ratios in agreement with the literature for the Hyades, Praesepe, and Be 32. We use a compilation of literature data to study Galactic trends of [Fe/H] and [α/Fe] with Galactocentric radius, age, and height above the Galactic plane. We find no significant trends, but some indication for a flattening of [Fe/H] at large R gc , and for younger ages in the inner disc. We also detect a possible decrease in [Fe/H] with |z| in the outer disc, and a weak increase in [α/Fe] with R gc .

Consistent metallicity scale for cool dwarfs and giants

“…We present here a comparison of our results with selected previous analyses of Hyades stars: Paulson et al (2003), Schuler et al (2006) and Carrera & Pancino (2011). These works were chosen because they have a larger number of stars in common with our analysis.…”

“…Spectroscopic studies of FGK-type dwarfs in the Hyades find a metallicity of about +0.13 dex (Cayrel et al 1985;Boesgaard & Friel 1990;Paulson et al 2003;Schuler et al 2006). Regarding the giants, the metallicity values range from +0.10 up to +0.20 dex, where this scatter is usually attributed to the star HIP 20455, a spectroscopic binary (Schuler et al 2006;Carrera & Pancino 2011).…”

“…Another analysis of the giants of the Hyades was performed by Carrera & Pancino (2011). These authors determined the atmospheric parameters via spectroscopy and photometry.…”

Chemical Cartography With Apogee: Large-Scale Mean Metallicity Maps of the Milky Way Disk

“…Previous studies for similar populations of stars measure slightly steeper slopes of −0.295 ± 0.005 dex kpc −1 (Chen et al 2003), −0.23 ± 0.04 dex kpc −1 (Bartašiūtė et al 2003), and −0.29 ± 0.06 dex kpc −1 (Marsakov & Borkova 2006). However, other studies of open clusters have found little evidence for a vertical gradient (Carrera & Pancino 2011;Jacobson et al 2011a). One potential explanation for the discrepancy is that previous studies did not take into account the radial gradient when measuring the vertical gradient (Carrera & Pancino 2011).…”

“…Various tracers have been used including Cepheid variables (e.g., Lemasle et al 2013), planetary nebulae (e.g., Henry et al 2010;Stanghellini & Haywood 2010), H ii regions (e.g., Balser et al 2011), open clusters (e.g., Carrera & Pancino 2011;Frinchaboy et al 2013), B stars (e.g., Daflon & Cunha 2004;Daflon et al 2009), and surveys of main sequence stars (e.g., Cheng et al 2012b for the Sloan Extension for Galactic Understanding and Exploration (SEGUE; Yanny et al 2009) of the Sloan Digital Sky Survey (SDSS; York 2000); Nordström et al 2004 for the GenevaCopenhagen Survey (GCS; Boeche et al 2013) for the Radial Velocity Experiment (Steinmetz et al 2006)). Near the solar circle, the measured amplitude of the Milky Way radial gradient ranges from −0.04 dex kpc −1 in [S/H] in OB stars (Daflon et al 2009) to −0.099 dex kpc −1 in [Fe/H] in main sequence stars between 4 < Gyr < 6 from the GCS (Nordström et al 2004).…”