TY - JOUR
T1 - An improved hertzsprung-russell diagram for the orion trapezium cluster
AU - Fang, Min
AU - Kim, Jinyoung Serena
AU - Pascucci, Ilaria
AU - Apai, Daniel
N1 - Funding Information:
Many thanks to the anonymous referee for comments that help to improve this paper. This material is based upon work supported by the National Aeronautics and Space Administration under Agreement No. NNX15AD94G for the program "Earths in Other Solar Systems." The results reported herein benefited from collaborations and/or information exchange within NASA Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate.
Publisher Copyright:
© 2021 Institute of Physics Publishing. All rights reserved.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/2/10
Y1 - 2021/2/10
N2 - We present a study of the Trapezium cluster in Orion. We analyze flux-calibrated Very Large Telescope/Multi- Unit Spectroscopic Explorer spectra of 361 stars to simultaneously measure the spectral types, reddening, and the optical veiling due to accretion. We find that the extinction law from Cardelli et al. with a total-to-selective extinction value of RV=5.5 is more suitable for this cluster. For 68% of the sample the new spectral types are consistent with literature spectral types within two subclasses but, as expected, we derive systematically later types than the literature by one to two subclasses for the sources with significant accretion levels. Here we present an improved Hertzsprung-Russell (H-R) diagram of the Trapezium cluster, in which the contamination by optical veiling on spectral types and stellar luminosities has been properly removed. A comparison of the locations of the stars in the H-R diagram with the non-magnetic and magnetic pre-main-sequence evolutionary tracks indicates an age of 1-2 Myr. The magnetic pre-main-sequence evolutionary tracks can better explain the luminosities of the low-mass stars. In the H-R diagram, the cluster exhibits a large luminosity spread (σ(Log La∗/L⊙) ~ 0.3). By collecting a sample of 14 clusters/groups with different ages, we find that the luminosity spread tends to be constant (σ(Log La∗/L⊙) ~ 0.2-0.25) after 2 Myr, which suggests that age spread is not the main cause of the luminosity spread. There are ~0.1 dex larger luminosity spreads for the younger clusters, e.g., the Trapezium cluster, than the older clusters, which can be explained by the starspots, accretion history, and circumstellar disk orientations.
AB - We present a study of the Trapezium cluster in Orion. We analyze flux-calibrated Very Large Telescope/Multi- Unit Spectroscopic Explorer spectra of 361 stars to simultaneously measure the spectral types, reddening, and the optical veiling due to accretion. We find that the extinction law from Cardelli et al. with a total-to-selective extinction value of RV=5.5 is more suitable for this cluster. For 68% of the sample the new spectral types are consistent with literature spectral types within two subclasses but, as expected, we derive systematically later types than the literature by one to two subclasses for the sources with significant accretion levels. Here we present an improved Hertzsprung-Russell (H-R) diagram of the Trapezium cluster, in which the contamination by optical veiling on spectral types and stellar luminosities has been properly removed. A comparison of the locations of the stars in the H-R diagram with the non-magnetic and magnetic pre-main-sequence evolutionary tracks indicates an age of 1-2 Myr. The magnetic pre-main-sequence evolutionary tracks can better explain the luminosities of the low-mass stars. In the H-R diagram, the cluster exhibits a large luminosity spread (σ(Log La∗/L⊙) ~ 0.3). By collecting a sample of 14 clusters/groups with different ages, we find that the luminosity spread tends to be constant (σ(Log La∗/L⊙) ~ 0.2-0.25) after 2 Myr, which suggests that age spread is not the main cause of the luminosity spread. There are ~0.1 dex larger luminosity spreads for the younger clusters, e.g., the Trapezium cluster, than the older clusters, which can be explained by the starspots, accretion history, and circumstellar disk orientations.
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U2 - 10.3847/1538-4357/abcec8
DO - 10.3847/1538-4357/abcec8
M3 - Article
AN - SCOPUS:85101539309
VL - 908
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - abcec8
ER -