The Distances to Open Clusters from Main‐Sequence Fitting. III. Improved Accuracy with Empirically Calibrated Isochrones

2006/07/31 by Deokkeun An, D. M. Terndrup, Donald M. Terndrup +5 · 10 citations
Mathematics · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Cluster (spacecraft) #Computer science #Gamma-ray bursts and supernovae #Helium #Mathematics #Metallicity #Open cluster #Photometry (optics) #Physics #Pleiades #Spectral line #Star cluster #Stars #Statistics #Stellar, planetary, and galactic studies #Systematic error #astro-ph

paper · pdf · doi:10.1086/509653

published as Astrophys.J.655:233-260,2007 · 28 pages, 23 figures; accepted for publication in the ApJ

arxiv created 2007/01/13 · openalex publication_date 2007/01/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We continue our series of papers on open cluster distances with a critical assessment of the accuracy of main-sequence fitting using isochrones that employ empirical corrections to the color-temperature relations. We use four nearby open clusters with multicolor photometry and accurate metallicities and present a new metallicity for Praesepe ([Fe/H] = +0.11 ± 0.03) from high-resolution spectra. The internal precision of distance estimates is about a factor of 5 better than the case without the color calibrations. After taking into account all major systematic errors, we obtain distances accurate to about 2%-3% when there exists a good metallicity estimate. Metallicities accurate to better than 0.1 dex may be obtained from BVI C K s photometry alone. We also derive a helium abundance for the Pleiades of Y = 0.279 ± 0.015, which is equal within the errors to the Sun's initial helium abundance and that of the Hyades. Our best estimates of distances are ( m - M ) 0 = 6.33 ± 0.04, 8.03 ± 0.04, and 9.61 ± 0.03 to Praesepe, NGC 2516, and M67, respectively. Our Pleiades distance at the spectroscopic metallicity, ( m - M ) 0 = 5.66 ± 0.01(internal) ± 0.05(systematic), is in excellent agreement with several geometric distance measurements. We have made calibrated isochrones for -0.3 ≤ [Fe/H] ≤ +0.2 available online.

Citations

• UBVRI photometry. II - The Cousins VRI system, its temperature and absolute flux calibration, and relevance for two-dimensional photometry
• Post–T Tauri Stars in the Nearest OB Association
• Absolute Dimensions of the M‐Type Eclipsing Binary YY Geminorum (Castor C): A Challenge to Evolutionary Models in the Lower Main Sequence
• A High Angular Resolution Multiplicity Survey of the Open Clusters α Persei and Praesepe
• Standard Photometric Systems
• The Problem ofHipparcosDistances To Open Clusters. II. Constraints From Nearby Field Stars
• Solar Models: Current Epoch and Time Dependences, Neutrinos, and Helioseismological Properties
• The problem of the Pleiades distance
• The open cluster distance scale
• The formation and evolution of binary systems

Cited by

• The helium abundance and ΔY/ΔZ in lower main-sequence stars
• Elemental abundances of low-mass stars in nearby young associations:AB Doradus, Carina Near and Ursa Major
• Abundances of four open clusters from solar stars
• THE X-RAY LUMINOSITY FUNCTION OF M37 AND THE EVOLUTION OF CORONAL ACTIVITY IN LOW-MASS STARS
• Stellar twins determine the distance of the Pleiades
• Pseudomagnitude distances: Application to the Pleiades cluster
• MASER OBSERVATIONS OF WESTERLUND 1 AND COMPREHENSIVE CONSIDERATIONS ON MASER PROPERTIES OF RED SUPERGIANTS ASSOCIATED WITH MASSIVE CLUSTERS
• A PHOTOMETRIC SURVEY FOR VARIABLES AND TRANSITS IN THE FIELD OF PRAESEPE WITH THE KILODEGREE EXTREMELY LITTLE TELESCOPE
• THE DISTANCES TO OPEN CLUSTERS FROM MAIN-SEQUENCE FITTING. V. EXTENSION OF COLOR CALIBRATION AND TEST USING COOL AND METAL-RICH STARS IN NGC 6791
• DEEP MMT TRANSIT SURVEY OF THE OPEN CLUSTER M37. III. STELLAR ROTATION AT 550 Myr