The Homogeneous Study of Transiting Systems (HoSTS) - II. The influence of the line list on stellar parameters

The use of high resolution, high signal-to-noise stellar spectra is essential in order to determine the most accurate and precise stellar atmospheric parameters via spectroscopy. This is particularly important for determining the fundamental parameters of exoplanets, which directly depend on the stellar properties. However, different techniques can be implemented when analysing these spectra which will influence the results. These include performing an abundance analysis relative to the solar values in order to negate uncertainties in atomic data, and fixing the surface gravity (log g) to an external value such as those from asteroseismology. The choice of lines used will also influence the results. In this paper, we investigate differential analysis and fixing log g for a set of FGK stars that already have accurate fundamental parameters known from external methods. We find that a differential line list gives slightly more accurate parameters compared to a laboratory line list, however the laboratory line list still gives robust parameters. We also find that fixing the log g does not improve the spectroscopic parameters. We investigate the effects of line selection on the stellar parameters and find that the choice of lines used can have a significant effect on the parameters. In particular, removal of certain low excitation potential lines can change the Teff by up to 50 K. For future HoSTS papers we will use the differential line list with a solar microturbulence value of 1 km/s, and we will not fix the log g to an external value.

[1]  D. F. Gray,et al.  The Observation and Analysis of Stellar Photospheres , 2021 .

[2]  R. P. Butler,et al.  THE PAN-PACIFIC PLANET SEARCH. VI. GIANT PLANETS ORBITING HD 86950 AND HD 222076 , 2016, 1611.07648.

[3]  K. Stassun,et al.  Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes , 2016, 1609.04389.

[4]  A. Korn,et al.  Gaia FGK benchmark stars: Effective temperatures and surface gravities , 2015, 1506.06095.

[5]  H. C. Stempels,et al.  A major upgrade of the VALD database , 2015 .

[6]  V. Adibekyan,et al.  Correcting the spectroscopic surface gravity using transits and asteroseismology - No significant effect on temperatures or metallicities with ARES and MOOG in local thermodynamic equilibrium , 2014, 1410.1310.

[7]  C. Soubiran,et al.  Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec , 2014, 1407.2608.

[8]  Astronomy,et al.  A new procedure for defining a homogenous line-list for solar-type stars , 2013, 1311.7169.

[9]  K. Cunha,et al.  THE HOMOGENEOUS STUDY OF TRANSITING SYSTEMS (HoSTS). I. THE PILOT STUDY OF WASP-13 , 2013, 1302.6115.

[10]  A. Cameron,et al.  Accurate spectroscopic parameters of WASP planet host stars , 2012, 1210.5931.

[11]  M. Holman,et al.  IMPROVED SPECTROSCOPIC PARAMETERS FOR TRANSITING PLANET HOSTS , 2012, 1208.1268.

[12]  P. Quirion,et al.  Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets , 2012 .

[13]  S. D. Kawaler,et al.  Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission , 2011, Science.

[14]  K. Cunha,et al.  ABUNDANCES OF STARS WITH PLANETS: TRENDS WITH CONDENSATION TEMPERATURE, , 2011, 1103.0757.

[15]  W. Cochran,et al.  SILICON AND OXYGEN ABUNDANCES IN PLANET-HOST STARS , 2010, 1106.5509.

[16]  B. Smalley,et al.  Accurate fundamental parameters for 23 bright solar-type stars , 2010, 1002.4268.

[17]  M. Asplund,et al.  Submitted to ApJL Preprint typeset using L ATEX style emulateapj v. 08/22/09 THE PECULIAR SOLAR COMPOSITION AND ITS POSSIBLE RELATION TO PLANET FORMATION , 2022 .

[18]  M. Asplund,et al.  The chemical composition of the Sun , 2009, 0909.0948.

[19]  A. Gimenez,et al.  Accurate masses and radii of normal stars: modern results and applications , 2009, 0908.2624.

[20]  Massachusetts Institute of Technology,et al.  Improving Stellar and Planetary Parameters of Transiting Planet Systems: The Case of TrES-2 , 2007, 0704.2938.

[21]  Wolfgang L. Wiese,et al.  A Critical Compilation of Atomic Transition Probabilities for Neutral and Singly Ionized Iron , 2006 .

[22]  K. Sadakane,et al.  Spectroscopic Determination of Atmospheric Parameters of Solar-Type Stars: Description of the Method and Application to the Sun , 2002 .

[23]  L. Girardi,et al.  Evolutionary tracks and isochrones for low- and intermediate-mass stars: From 0.15 to 7 , and from to 0.03 , 1999, astro-ph/9910164.

[24]  H. C. Stempels,et al.  VALD{2: Progress of the Vienna Atomic Line Data Base ? , 1999 .

[25]  Johannes Andersen,et al.  Accurate masses and radii of normal stars , 1991 .

[26]  Ingemar Furenlid,et al.  Solar flux atlas from 296 to 1300 nm , 1985 .

[27]  O. Struve,et al.  On the Intensities of Stellar Absorption Lines. , 1932, Proceedings of the National Academy of Sciences of the United States of America.

[28]  Blaine A. Bell,et al.  Atomic Line Data , 1995 .