Red supergiant stars in IC 1613 and metallicity-dependent mixing length in the evolutionary model

Abstract

We report a spectroscopic study on red supergiant stars (RSGs) in the irregular dwarf galaxy IC 1613 in the Local Group. We derive the effective temperatures ($T_{\mathrm{eff}}$) and metallicities of 14 RSGs by synthetic spectral fitting to the spectra observed with the MMIRS instrument on the MMT telescope for a wavelength range from 1.16 $\mu$m to 1.23 $\mu$m. A weak bimodal distribution of the RSG metallicity centered on the [Fe/H]=$-0.65$ is found, which is slightly lower than or comparable to that of the Small Magellanic Cloud (SMC). There is no evidence for spatial segregation between the metal rich ([Fe/H]$>-0.65$) and poor ([Fe/H]$<-0.65$) RSGs throughout the galaxy. The mean effective temperature of our RSG sample in IC 1613 is higher by about 250 K than that of the SMC. However, no correlation between $T_{\mathrm{eff}}$ and metallicity within our RSG sample is found. We calibrate the convective mixing length (${\alpha }_{\mathrm{MLT}}$) by comparing stellar evolutionary tracks with the RSG positions on the HR diagram, finding that models with ${\alpha }_{\mathrm{MLT}}=2.2-2.4H_P$ can best reproduce the effective temperatures of the RSGs in IC 1613 for both Schwarzschild and Ledoux convection criteria. This result supports our previous study that a metallicity dependent mixing length is needed to explain the RSG temperatures observed in the Local Group, but we find that this dependency becomes relatively weak for RSGs having a metallicity equal to or less than the SMC metallicity.

arXiv comment15 pages, 7 figures, accepted in ApJ

References in corpus (55)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought
• The Effective Temperatures and Physical Properties of Magellanic Cloud Red Supergiants: The Effects of Metallicity
• The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization
• The temperatures of Red Supergiants
• Deep Hubble Space Telescope Imaging of IC 1613 II. The Star Formation History
• The Correlation Between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era
• Red Supergiant Stars as Cosmic Abundance Probes: II. NLTE Effects in J-band Silicon Lines
• The luminosities of cool supergiants in the Magellanic Clouds, and the Humphreys-Davidson limit revisited
• Nebular Abundances of Nearby Southern Dwarf Galaxies
• VLT spectroscopy of blue supergiants in IC 1613
• Deep HST Imaging of IC 1613. I. Variable Stars and Distance
• Calibrating Convective properties of Solar-like Stars in the Kepler Field of View
• Red Supergiants in the Andromeda Galaxy (M31)
• The Yellow and Red Supergiants of M33
• The ACS LCID project. X. The Star Formation History of IC 1613: Revisiting the Over-Cooling Problem
• Stellar Populations at the Center of IC 1613
• The Araucaria Project. The Distance to the Local Group Galaxy IC 1613 from Near-Infrared Photometry of Cepheid Variables
• Red Supergiant Stars as Cosmic Abundance Probes: KMOS Observations in NGC 6822
• Red Supergiant Stars as Cosmic Abundance Probes: NLTE Effects in J-band Iron and Titanium Lines
• Classically and Asteroseismically constrained 1D Stellar Evolution Models of $\alpha$ Centauri A and B using Empirical Mixing Length Calibrations
• Red Supergiant Stars as Cosmic Abundance Probes. III. NLTE effects in J-band Magnesium lines
• An LTE effective temperature scale for red supergiants in the Magellanic clouds
• Red Supergiants as Cosmic Abundance Probes: The Magellanic Clouds
• The potential of Red Supergiants as extra-galactic abundance probes at low spectral resolution
• Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC1613
• No breakdown of the radiatively-driven wind theory in low-metallicity environments
• Spectral Types of Red Supergiants in NGC 6822 and the Wolf-Lundmark-Melotte Galaxy
• Luminous and Variable Stars in M31 and M33. III. The Yellow and Red Supergiants and Post-Red Supergiant Evolution
• Stellar Content and Recent Star Formation History of the Local Group Dwarf Irregular Galaxy IC1613
• Evolutionary models of red supergiants: Evidence for a metallicity-dependent mixing length and implications for Type IIP supernova progenitors
• The nature of V39: an LBV candidate or LBV impostor in the very low metallicity galaxy IC 1613?
• Data Reduction Pipeline for the MMT and Magellan Infrared Spectrograph
• Spectral type, temperature and evolutionary stage in cool supergiants
• Quantitative Spectroscopic J-band Study of Red Supergiants in Perseus OB-1
• Identification of red supergiants in nearby galaxies with mid-IR photometry
• Method to Estimate the Effective Temperatures of Late-Type Giants using Line-Depth Ratios in the Wavelength Range 0.97-1.32$\mu$m
• Effective temperatures of red supergiants estimated from line-depth ratios of iron lines in the YJ bands, 0.97--1.32 micron
• The impact of winds on the spectral appearance of Red Supergiants
• Characterisation of red supergiants in the Gaia spectral range
• Quantitative Spectroscopy of Supergiants in the Local Group Dwarf Galaxy IC 1613: Metallicity and Distance
• The AGB population in IC 1613 using JHK photometry
• Identification of dusty massive stars in star-forming dwarf irregular galaxies in the Local Group with mid-IR photometry
• Physical parameters of red supergiants in dwarf irregular galaxies in the Local Group
• Hyper Wide Field Imaging of the Local Group Dwarf Irregular Galaxy IC 1613: An Extended Component of Metal-poor Stars
• Interstellar Medium Surrounding the WO Star in the Galaxy IC 1613: New Optical and Radio Observations
• Massive stars in the Sagittarius Dwarf Irregular Galaxy
• The temperatures of red supergiants in low metallicity environments

Cited by in corpus (4)

• MAGIS (Measuring Abundances of red super Giants with Infrared Spectroscopy) project I. Establishment of an abundance analysis procedure for red supergiants and its evaluation with nearby stars
• Investigating episodic mass loss in evolved massive stars: III. Spectroscopy of dusty massive stars in three northern galaxies
• A machine-learning photometric classifier for massive stars in nearby galaxies II. The catalog
• From gas to stars: MUSEings on the internal evolution of IC 1613