Spectroscopic parameters for 451 stars in the HARPS GTO planet search program - Stellar [Fe/H] and the frequency of exo-Neptunes

By Sérgio F. Sousa, Nuno C. Santos, M. Mayor, S. Udry, Luca Casagrande, G. Israelian, F. Pepe, D. Queloz, M. Monteiro. 2008

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To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) “high precision” sample. Spectroscopic stellar parameters were measured using high signal-to-noise ($S/N$) spectra acquired with the HARPS spectrograph. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and the recent ARES code for measuring line equivalent widths. We show that our results agree well with those ones presented in the literature (for stars in common). We present a useful calibration for the effective temperature as a function of the index color $B-V$ and [Fe/H]. We use our results to study the metallicity-planet correlation, namely for very low mass planets. The results presented here suggest that in contrast to their jovian couterparts, neptune-like planets do not form preferentially around metal-rich stars. The ratio of jupiter-to-neptunes is also an increasing function of stellar metallicity. These results are discussed in the context of the core-accretion model for planet formation.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b1c9098e1293fcf89905c35d1252dc40a1b4c42d

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Citations in the corpus

Accurate fundamental parameters for 23 bright solar-type stars (2010, background): “Each column is identified by the first author, i.e. Fuhrmann (1998, 2004, 2008), Sousa et al. (2008), Soubiran et al. (1998), Santos et al. (2004, 2005), and Valenti & Fischer (2005).”
SOPHIE velocimetry of Kepler transit candidates VII. A false-positive rate of 35% for Kepler close-in giant candidates (2012, background): “For details we refer the reader to Santos et al. (2004) and Sousa et al. (2008).”
METALLICITY AND TEMPERATURE INDICATORS IN M DWARF K-BAND SPECTRA: TESTING NEW AND UPDATED CALIBRATIONS WITH OBSERVATIONS OF 133 SOLAR NEIGHBORHOOD M DWARFS (2011, result): “These results are in agreement with what is observed for FGK stars, where Neptunes and super-Earths, unlike Jupiters, do not seem to form preferentially around highly metal-rich ([Fe/H]> 0.2 dex) stars (Sousa et al. 2008; Mayor et al. 2011).”
ON THE METAL RICHNESS OF M DWARFS WITH PLANETS (2009, background): “For example, the relationship between minimum planet mass (MP sin i) and host-star metallicity has recently received attention from several recent studies (Sousa et al. 2008; Howard et al. 2009).”
An absolutely calibrated T eff scale from the infrared flux method. Dwarfs and subgiants (2010, methodology): “…the effective temperatures determined from high resolution spectroscopy of solar neighbourhood stars and a version of the IRFM similar to that adopted here has been already carried Casagrande et al.: The eff ctive temperature scale: resolving different versions 13 out in Sousa et al. (2008).”
Spectroscopic stellar parameters for 582 FGK stars in the HARPS volume-limited sample. Revising the metallicity-planet correlation (2011, methodology): “As expected, this value is compatible with both comparison samples presented before in previous works (Santos et al., 2004; Sousa et al., 2008) and the original sample of CORALIE, as can be seen in the work of Santos et al. (2004) and later in this work in the top panel of Fig.”
Homogeneous studies of transiting extrasolar planets – IV. Thirty systems with space-based light curves (2011, methodology): “The TychoB−V value (Høg et al. 1997) supplemented by the calibration of Sousa et al. (2008)returnsTeff = 4852K.”
The Occurrence and Architecture of Exoplanetary Systems (2014, background): “In contrast, small-planet occurrence is not associated with metallicity in FGK dwarfs (Sousa et al. 2008, Buchhave et al. 2012).”
Chemical abundances of 451 stars from the HARPS GTO planet search program - Thin disc, thick disc, and planets (2009, methodology): “We also plotted the [CrI/CrII] value as a function of the stellar parameters to ensure that the ionisation equilibrium enforced on the FeII lines (Sousa et al. 2008) was acceptable to other elements.”
SOPHIE velocimetry of Kepler transit candidates XVII. The physical properties of giant exoplanets within 400 days of period (2015, methodology): “The median metallicity of dwarfs in the solar neighborhood has been found to be of about -0.08 dex (Sousa et al. 2008) and ∼ 0 dex for both CoRoT pointing directions (Gazzano et al. 2010; Cortés et al. 2015).”
The planet search programme at the ESO CES and HARPS - IV. The search for Jupiter analogues around solar-like stars (2012, background): “4.5, assumingTeff = 5729±17K and [Fe/H] = 0.19± 0.01 from Sousa et al. 2008). α Cen A+B: We refer to Pourbaix et al. (2002) for the orbital solution forα Cen A+B with a period of 80 yr.”
Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program - Galactic stellar populations and planets (2012, methodology): “The lines were constructed using the calibration equation from Sousa et al (2008).”
Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, background): “…are based on either excitation equilibrium for about 40 Fe I lines (Santos et al. 2001, 2004; Affer et al. 2005), excitation equilibrium for about 400 or 250 Fe I lines (Luck & Heiter 2005; Sousa et al. 2008), or on spectrum synthesis for a mixture of weak and strong lines (Valenti & Fischer 2005).”
The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “Between 1–4 R⊕, the planet-metallicity correlation is weaker across spectral type (Sousa et al., 2008; Mayor et al., 2011; Schlaufman & Laughlin, 2011).”
The Solar Twin Planet Search. I. Fundamental parameters of the stellar sample (2014, result): “For now, it is interesting to compare our spectroscopic parameters with those determined by Sousa et al. (2008), who employed essentially the same technique used in this work, but with some differences regarding the ingredients of the process.”
Lithium depletion in solar-like stars: no planet connection (2010, methodology): “…robust comparison, we have restricted the comparison sample using the following criteria: we only considered comparison objects within a 2σ range in [Fe/H], logg, and Teff around planet hosts, whereσ are the average values of the uncertainties in the stellar parameters given by Sousa et al. (2008).”