A Caltech Library Service

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

Cao, Lyra and Pinsonneault, Marc H. and Hillenbrand, Lynne A. and Kuhn, Michael A. (2022) Age Spreads and Systematics in λ Orionis with Gaia DR2 and the SPOTS Tracks. Astrophysical Journal, 924 (2). Art. No. 84. ISSN 0004-637X. doi:10.3847/1538-4357/ac307f.

[img] PDF - Published Version
Creative Commons Attribution.

[img] PDF - Accepted Version
Creative Commons Attribution.


Use this Persistent URL to link to this item:


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, λ 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 interstellar medium, with variable local extinction, motivates a star-by-star dereddening approach. We use a spectral energy distribution 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 ± 0.2 Myr in the SPOTS model (f = 0.34). We find that star-by-star dereddening methods distinguishing between pre-main-sequence classes provide a smaller age spread than techniques using a uniform extinction, and we infer a minimum age spread of 0.19 dex and a typical age spread of 0.35 dex after modeling age distributions convolved with observed errors. This suggests that the λ Ori cluster may have a long star formation timescale and that spotted stellar models significantly change age estimates for young clusters.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Cao, Lyra0000-0002-8849-9816
Pinsonneault, Marc H.0000-0002-7549-7766
Kuhn, Michael A.0000-0002-0631-7514
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2020 November 17; revised 2021 October 13; accepted 2021 October 14; published 2022 January 14. We thank Diego Godoy-Rivera for sharing open-cluster membership data from Gaia in advance of publication. We thank Deokkeun An for sharing open-cluster data products, as well as Marina Kounkel and Richard Olney for sharing relevant data products from APOGEE Net. We wish to thank Diego Godoy-Rivera and Tharindu Jayasinghe for useful discussions. We thank the anonymous referee for their extensive suggestions, which greatly improved this work. M.H.P. and L.C. acknowledge support from NASA grant 80NSSC19K0597. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Group:Astronomy Department
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Stellar activity; Pre-main sequence stars; Fundamental parameters of stars; Star clusters; Young star clusters; Young stellar objects; Stellar evolutionary models
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Stellar activity (1580); Pre-main sequence stars (1290); Fundamental parameters of stars (555); Star clusters (1567); Young star clusters (1833); Young stellar objects (1834); Stellar evolutionary models (2046)
Record Number:CaltechAUTHORS:20220119-572336000
Persistent URL:
Official Citation:Lyra Cao et al 2022 ApJ 924 84
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112982
Deposited By: George Porter
Deposited On:20 Jan 2022 15:03
Last Modified:20 Jan 2022 15:03

Repository Staff Only: item control page