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Evolution of X-Ray Activity in <25 Myr Old Pre-main Sequence Stars

Getman, Konstantin V. and Feigelson, Eric D. and Garmire, Gordon P. and Broos, Patrick S. and Kuhn, Michael A. and Preibisch, Thomas and Airapetian, Vladimir S. (2022) Evolution of X-Ray Activity in <25 Myr Old Pre-main Sequence Stars. Astrophysical Journal, 935 (1). Art. No. 43. ISSN 0004-637X. doi:10.3847/1538-4357/ac7c69.

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Measuring the evolution of X-ray emission from pre-main-sequence (PMS) stars gives insight into two issues: the response of magnetic dynamo processes to changes in the interior structure, and the effects of high-energy radiation on protoplanetary disks and primordial planetary atmospheres. We present a sample of 6003 stars with ages 7–25 Myr in 10 nearby open clusters from Chandra X-ray and Gaia-EDR3 surveys. Combined with previous results in large samples of younger (≲5 Myr) stars in MYStIX and SFiNCs star-forming regions, mass-stratified activity-age relations are derived for the early phases of stellar evolution. X-ray luminosity (L_X) is constant during the first few Myr, possibly due to the presence of extended X-ray coronas insensitive to temporal changes in stellar size. L_X then decays during the 7–25 Myr period, more rapidly as stellar mass increases. This decay is interpreted as decreasing efficiency of the α² dynamo as radiative cores grow and a solar-type αΩ dynamo emerges. For more massive 3.5–7 M_⊙ fully radiative stars, the X-ray emission plummets—indicating the lack of an effective magnetic dynamo. The findings provide improved measurements of high-energy radiation effects on circumstellar material, first for the protoplanetary disk and then for the atmospheres of young planets. The observed X-ray luminosities can be so high that an inner Earth-mass rocky, unmagnetized planet around a solar-mass PMS star might lose its primary and secondary atmospheres within a few (several) million years. PMS X-ray emission may thus have a significant impact on the evolution of early-planetary atmospheres and the conditions promoting the rise of habitability.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Getman, Konstantin V.0000-0002-6137-8280
Feigelson, Eric D.0000-0002-5077-6734
Garmire, Gordon P.0000-0002-7371-5416
Broos, Patrick S.0000-0002-7872-2025
Kuhn, Michael A.0000-0002-0631-7514
Preibisch, Thomas0000-0003-3130-7796
Airapetian, Vladimir S.0000-0003-4452-0588
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 2022 March 3; revised 2022 June 2; accepted 2022 June 10; published 2022 August 12. We thank the anonymous referee for his time and many useful comments that improved this work. We thank L. Townsley (Penn State) for sharing the Chandra data products for the open clusters NGC 3293 and NGC 869 with us. This project is supported by the Chandra grant GO9-20011X (K. Getman, Principal Investigator) and the Chandra ACIS Team contract SV474018 (G. Garmire & L. Townsley, Principal Investigators), issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. The Chandra Guaranteed Time Observations (GTO) data used here were selected by the ACIS Instrument Principal Investigator, Gordon P. Garmire, of the Huntingdon Institute for X-ray Astronomy, LLC, which is under contract to the Smithsonian Astrophysical Observatory; contract SV2-82024. The work of T.P. was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under project numbers 325594231 and 362051796. V.S. Airaoetian acknowledges support from the NASA/GSFC Sellers Exoplanet Environments Collaboration (SEEC), which is funded by the NASA Planetary Science Division's Internal Scientist Funding Model (ISFM). 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. Facilities: CXO, Gaia. Software:ACIS Extract (Broos et al. 2010), R (R Core Team 2020), XSPEC (Arnaud 1996).
Funding AgencyGrant Number
Smithsonian Astrophysical ObservatorySV2-82024
Deutsche Forschungsgemeinschaft (DFG)325594231
Deutsche Forschungsgemeinschaft (DFG)362051796
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Pre-main sequence stars; Planetary atmospheres; Protoplanetary disks; Stellar x-ray flares; Single x-ray stars; X-ray stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Pre-main sequence stars (1290); Planetary atmospheres (1244); Protoplanetary disks (1300); Stellar x-ray flares (1637); Single x-ray stars (1461); X-ray stars (1823)
Record Number:CaltechAUTHORS:20220815-504702000
Persistent URL:
Official Citation:Konstantin V. Getman et al 2022 ApJ 935 43
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116285
Deposited By: George Porter
Deposited On:16 Aug 2022 14:20
Last Modified:16 Aug 2022 14:20

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