Theoretical analysis of surface brightness-colour relations for late-type stars using MARCS model atmospheres

Abstract

Surface brightness-colour relations (SBCRs) are largely used for general studies in stellar astrophysics and for determining extragalactic distances. Based on simulated spectra of late-type stars using MARCS model atmospheres, our aim is to analyse the effect of stellar fundamental parameters on the surface brightness. We also compare theoretical and recent empirical SBCRs. We used MARCS model atmospheres to compute spectra and the surface brightness of stars. We first explored the parameter space of MARCS (i.e. effective temperature, $\log g$, $[Fe/H]$, microturbulence, and mass) in order to quantify their impact on the surface brightness. Then we considered a relation between the effective temperature and $\log g$ for late dwarfs and giants, as well as a solar metallicity, in order to allow a consistent comparison of theoretical and empirical SBCRs. We find that the SBCR is not sensitive to the microturbulence and mass. The effect of metallicity on the SBCR is found to be larger for dwarfs than for giants. It is also larger when considering larger $V-K_s$ values. We also find that a difference of 0.5 dex in metallicity between Galactic and LMC SBCRs does not affect the recent LMC distance determination, based on eclipsing binaries, by more than 0.4%. By comparing theoretical with empirical SBCRs, we find a good agreement of less than 2$\sigma$ for F5-K7 dwarfs and giants stars, while a larger discrepancy is found for M dwarfs and giants (about 4-6$\sigma$). The surface gravity properties, as modelled in MARCS, explain the differences in the empirical SBCRs in terms of class. We finally find that theoretical and empirical SBCRs for Cepheids are consistent. Carefully considering metallicity and $\log g$ is mandatory when calibrating or using SBCRs.

References in corpus (23)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Basic physical parameters of a selected sample of evolved stars
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• First Results from the CHARA Array VII: Long-Baseline Interferometric Measurements of Vega Consistent with a Pole-On, Rapidly Rotating Star
• Abundances in the Local Region II: F, G and K Dwarfs and Subgiants
• Revised Filter Profiles and Zero Points for Broadband Photometry
• The lithium abundances for a large sample of red giants
• Stellar atmospheric parameters for 754 spectra from the X-shooter Spectral Library
• MARCS model atmospheres
• The VMC survey -- XLIV: Mapping metallicity trends in the Large Magellanic Cloud using near-infrared passbands
• Abundances of disk and Bulge giants from high-resolution optical spectra III. Sc, V, Cr, Mn, Co, Ni
• Improving the surface brightness-color relation for early-type stars using optical interferometry
• Inspecting the Cepheid parallax of pulsation using Gaia EDR3 parallaxes. Projection factor and period-luminosity and period-radius relations
• HARPS-N high spectral resolution observations of Cepheids I. The Baade-Wesselink projection factor of δ Cep revisited
• A thin shell of ionized gas explaining the IR excess of classical Cepheids
• Determination of the spectroscopic stellar parameters for 257 field giant stars
• Progress on the calibration of surface brightness-color relations for early- and late-type stars
• Precise calibration of the dependence of surface brightness-colour relations on colour and class for late-type stars
• Extended envelopes around Galactic Cepheids. V. Multi-wavelength and time-dependent analysis of IR excess
• The metallicity sensitivity of a surface brightness temperature scale

Cited by in corpus (4)

• HARPS-N high spectral resolution observations of Cepheids II. The impact of the surface-brightness color relation on the Baade-Wesselink projection factor of eta Aql
• CHARA/SPICA: a 6-telescope visible instrument for the CHARA Array
• Characterisation of magnetic activity of M dwarfs. Possible impact on the surface brightness
• Surface brightness-color relations for red giant branch stars using asteroseismic radii and Gaia distances (the ARD method)