Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37

Huan Y.A. Meng, G. H. Rieke, Jinyoung Serena Kim, Aurora Sicilia-Aguilar, N. J.G. Cross, Taran Esplin, L. M. Rebull, Klaus W. Hodapp

Research output: Contribution to journalArticle

Abstract

We have monitored nearly a square degree in IC 1396A/Tr 37 over 21 epochs extending over 2014-2016 for sources variable in the JHK bands. In our data, 65% ±8% of previously identified cluster members show variations, compared with ≲0.3% of field stars. We identify 119 members of Tr 37 on the basis of variability, forming an unbiased sample down to the brown dwarf regime. The K-band luminosity function in Tr 37 is similar to that of IC 348 but shifted to somewhat brighter values, implying that the K- and M-type members of Tr 37 are younger than those in IC 348. We introduce methods to classify the causes of variability, based on behavior in the color-color and color-magnitude diagrams. Accretion hot spots cause larger variations at J than at K with substantial scatter in the diagrams; there are at least a dozen, with the most active resembling EXors. Eleven sources are probably dominated by intervention of dust clumps in their circumstellar disks, with color behavior indicating the presence of grains larger than for interstellar dust, presumably due to grain growth in their disks. Thirteen sources have larger variations at K than at J or H. For 11 of them, the temperature fitted to the variable component is very close to 2000 K, suggesting that the changes in output are caused by turbulence at the inner rim of the circumstellar disk exposing previously protected populations of grains.

Original languageEnglish (US)
Article number7
JournalAstrophysical Journal
Volume878
Issue number1
DOIs
StatePublished - Jun 10 2019

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Keywords

  • infrared: planetary systems
  • infrared: stars
  • open clusters and associations: individual (Tr 37)
  • protoplanetary disks
  • stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Meng, H. Y. A., Rieke, G. H., Kim, J. S., Sicilia-Aguilar, A., Cross, N. J. G., Esplin, T., Rebull, L. M., & Hodapp, K. W. (2019). Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37. Astrophysical Journal, 878(1), [7]. https://doi.org/10.3847/1538-4357/ab1b14