Age Spreads and Systematics in λ Orionis with Gaia DR2 and the SPOTS tracks

Abstract

In this paper we investigate the robustness of age measurements, age spreads, and stellar models in young pre-main sequence stars. For this effort, we study a young cluster, $\lambda$ Orionis, within the Orion star-forming complex. We use Gaia data to derive a sample of 357 targets with spectroscopic temperatures from spectral types or from the automated spectroscopic pipeline in APOGEE Net. After accounting for systematic offsets between the spectral type and APOGEE temperature systems, the derived properties of stars on both systems are consistent. The complex ISM, with variable local extinction, motivates a star-by-star dereddening approach. We use a spectral energy distribution (SED) fitting method calibrated on open clusters for the Class III stars. For the Class II population, we use a Gaia G-RP dereddening method, minimizing systematics from disks, accretion, and other physics associated with youth. The cluster age is systematically different in models incorporating the structural impact of starspots or magnetic fields than in nonmagnetic models. Our mean ages range from 2-3 Myr (nonmagnetic models) to 3.9$\pm$0.2 Myr in the SPOTS model (f=0.34). We find star-by-star dereddening methods distinguishing between pre-MS classes provide a smaller age spread than techniques using a uniform extinction, and infer a minimum age spread of 0.19 dex and a typical age spread of 0.35 dex after modelling age distributions convolved with observed errors. This suggests that the $\lambda$ Ori cluster may have a long star formation timescale and that spotted stellar models significantly change age estimates for young clusters.

arXiv comment23 pages, 19 figures. Accepted for publication in the Astrophysical Journal

References in corpus (51)

• Galactic Stellar and Substellar Initial Mass Function
• Gaia Data Release 2. Summary of the contents and survey properties
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars
• The Dartmouth Stellar Evolution Database
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• The Pan-STARRS1 Database and Data Products
• Slow Star Formation in Dense Gas: Evidence and Implications
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• The Ages of Stars
• Kinematics in Young Star Clusters and Associations with Gaia DR2
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. III. A Consistent 10 Myr Age for the Upper Scorpius OB Association
• The APOGEE-2 Survey of the Orion Star Forming Complex II: Six-dimensional structure
• The Big Problems in Star Formation: the Star Formation Rate, Stellar Clustering, and the Initial Mass Function
• Equilibrium Star Cluster Formation
• Rotation in the Pleiades with K2: I. Data and First Results
• On the Rapid Collapse and Evolution of Molecular Clouds
• The ASAS-SN Catalog of Variable Stars II: Uniform Classification of 412,000 Known Variables
• A Multi-color Optical Survey of the Orion Nebula Cluster. II. the H-R diagram
• The Distances to Open Clusters from Main-Sequence Fitting. III. Improved Accuracy with Empirically Calibrated Isochrones
• Rotation of Low-Mass Stars in Upper Scorpius and Rho Ophiuchus with K2
• Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation
• A maximum likelihood method for fitting colour-magnitude diagrams
• Placing the spotted T Tauri star LkCa 4 on an HR diagram
• Bayesian inference of stellar parameters and interstellar extinction using parallaxes and multiband photometry
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• The SPOTS Models: A Grid of Theoretical Stellar Evolution Tracks and Isochrones For Testing The Effects of Starspots on Structure and Colors
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. II. Fully Convective Main Sequence Stars
• No wide spread of stellar ages in the Orion Nebula Cluster
• Masses and Implications for Ages of Low-Mass Pre-Main Sequence Stars in Taurus and Ophiuchus
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region. I. Enlarging the census down to the planetary mass domain in Collinder 69
• Age Determination in Upper Scorpius with Eclipsing Binaries
• Structure, kinematics, and ages of the young stellar populations in the Orion region
• Self-Consistent Magnetic Stellar Evolution Models of the Detached, Solar-Type Eclipsing Binary EF Aquarii
• A Photometric Study of the Young Stellar Population Throughout the lambda Orionis Star-Forming Region
• FLAMES spectroscopy of low-mass stars in the young clusters sigma Ori and lambda Ori
• Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region
• SPITZER: Accretion in Low Mass Stars and Brown Dwarfs in the Lambda Orionis Cluster
• Stellar Rotation in the Gaia Era: Revised Open Clusters Sequences
• Spitzer Observations of the Lambda Orionis cluster. II. Disks around solar-type and low mass stars
• NGC 1980 is not a foreground population of Orion: Spectroscopic survey of young stars with low extinction in Orion A
• APOGEE Net: Improving the derived spectral parameters for young stars through deep learning
• The Gaia-ESO Survey: age spread in the star forming region NGC6530 from the HR diagram and gravity indicators
• M Dwarf rotation from the $K2$ young clusters to the field. I. A Mass-Rotation Correlation at 10 Myr
• Undetected Binary Stars Cause an Observed Mass Dependent Age Gradient in Upper Scorpius
• The Gaia-ESO Survey: Membership probabilities for stars in 32 open clusters from 3D kinematics
• The APOGEE-2 Survey of the Orion Star Forming Complex: I. Target Selection and Validation with early observations
• Spectroscopic Assessment of WISE-based Young Stellar Object Selection

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• Modules for Experiments in Stellar Astrophysics (MESA): Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure
• Starspots and Magnetism: Testing the Activity Paradigm in the Pleiades and M67
• TESS Hunt for Young and Maturing Exoplanets (THYME) IX: a 27 Myr extended population of Lower-Centaurus Crux with a transiting two-planet system
• Emission line variability of young 10-30 Mjup companions : I. The case of GQ Lup b and GSC 06214-00210 b
• Low Mass Stars as Tracers of Star and Cluster Formation
• ABYSS I: Targeting strategy for APOGEE & BOSS young star survey in SDSS-V
• Expansion Kinematics of Young Clusters. I. Lambda Ori
• 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
• Rotational evolution of young-to-old stars with data-driven three-dimensional wind models
• Constraints on star formation in Orion A from Gaia
• Using a neural network approach and starspots dependent models to predict effective temperatures and ages of young stars