An Improved HR Diagram for the Orion Trapezium Cluster

Abstract

In this paper, we present a study of the Trapezium cluster in Orion. We analyze flux-calibrated VLT/MUSE 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. (1989) with a total-to-selective extinction value of $R_{\mathrm{V}}=$5.5 is more suitable for this cluster. For 68% of the sample the new spectral types are consistent with literature spectral types within 2 subclasses, but as expected, we derive systematically later types than the literature by one to two subclasses for the sources with significant accretion levels. Here we present an improved Hertzsprung-Russell (H-R) diagram of the Trapezium cluster, in which the contamination by optical veiling on spectral types and stellar luminosities has been properly removed. A comparison of the locations of the stars in the H-R diagram with the non-magnetic and magnetic pre-main sequence evolutionary tracks indicates an age of 1--2~Myr. The magnetic pre-main sequence evolutionary tracks can better explain the luminosities of the low-mass stars. In the H-R diagram, the cluster exhibits a large luminosity spread ($\sigma$(Log~$L_{\star }/L_{\odot })\sim$0.3). By collecting a sample of 14 clusters/groups with different ages, we find that the luminosity spread tends to be constant ($\sigma$(Log~$L_{\star }/L_{\odot })\sim$0.2--0.25) after 2~Myr, which suggests that age spread is not the main cause of the spread. There are $\sim$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.

31 pages, 16 figurs, 3 tables, accepted by ApJ

References in corpus (25)

• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• X-Shooter spectroscopy of young stellar objects in Lupus: Accretion properties of class II and transitional objects
• A Steeper than Linear Disk Mass-Stellar Mass Scaling Relation
• An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties
• The Stellar Population of the Chamaeleon I Star-Forming Region
• The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular Clouds
• Placing the spotted T Tauri star LkCa 4 on an HR diagram
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• The Spatial Distribution of Brown Dwarfs in Taurus
• A Survey for New Members of the Taurus Star-Forming Region with the Sloan Digital Sky Survey
• FLAMES spectroscopy of low-mass stars in the young clusters sigma Ori and lambda Ori
• Discovery of an M9.5 Candidate Brown Dwarf in the TW Hydrae Association - DENIS J124514.1-442907
• An extensive VLT/X-Shooter library of photospheric templates of pre-main sequence stars
• Infrared Spectroscopy and Analysis of Brown Dwarf and Planetary Mass Objects in the Orion Nebula Cluster
• Optical Spectroscopic Classification and Membership of Young M Dwarfs in Star-Forming Regions
• Self-consistent evolution of accreting low-mass stars and brown dwarfs
• The Keele-Exeter young cluster survey: I. Low mass pre-main sequence stars in NGC 2169
• The Gaia-ESO Survey and CSI 2264: Substructures, disks, and sequential star formation in the young open cluster NGC 2264
• A spectroscopic census in young stellar regions: the Sigma Orionis cluster
• Substellar Objects in Nearby Young Clusters (SONYC) VIII: Substellar population in Lupus 3
• X-Shooter observations of low-mass stars in the Eta Chamaeleontis association
• Age spreads and the temperature dependence of age estimates in Upper Sco
• Star-disk interactions in multi-band photometric monitoring of the classical T Tauri star GI Tau
• An optical spectroscopic H-R diagram for low-mass stars and brown dwarfs in Orion
• Gas absorption and dust extinction towards the Orion Nebula Cluster

Cited by in corpus (17)

• A High-resolution Optical Survey of Upper Sco: Evidence for Coevolution of Accretion and Disk Winds
• High-resolution [O I] line spectral mapping of TW Hya supportive of a magnetothermal wind
• Kaleidoscope of irradiated disks: MUSE observations of proplyds in the Orion Nebula Cluster. I. Sample presentation and ionization front sizes
• SDSS-V Local Volume Mapper (LVM): A Glimpse into Orion
• [OI] 6300Å emission as a probe of external photoevaporation of protoplanetary discs
• Chemical modeling of Orion Nebula Cluster disks: evidence for massive, compact gas disks with ISM-like gas-to-dust ratios
• A Novel Method to Estimate the FUV Flux and a Catalogue for Star-Hosting Discs in Nearby Star-Forming Regions
• Star formation in IC1396: Kinematics and subcluster structure revealed by Gaia
• An APEX search for carbon emission from NGC 1977 proplyds
• The population of young low-mass stars in Trumpler 14
• NGTS clusters survey $-$ V: Rotation in the Orion Star-forming Complex
• The NEMESIS Catalogue of Young Stellar Objects for the Orion Star Formation Complex. I. General description of data curation
• A census of young stellar objects in two line-of-sight star forming regions toward IRAS 22147+5948 in the outer Galaxy
• Line ratio identification of external photoevaporation
• Spectral classification of young stars using conditional invertible neural networks II. Application to Trumpler 14 in Carina
• PDRs4All XVIII. JWST-NIRCam Photometric properties of protoplanetary disks in the Orion Nebula Cluster
• The Sejong Open Cluster Survey (SOS). VII. A Photometric Study of the Young Open Cluster IC 1590