Extreme infrared variables from UKIDSS-I: A concentration in star-forming regions

C. Contreras Peña, P.W. Lucas, D. Froebrich, M.S.N. Kumar, J. Goldstein, J.E. Drew, A.J. Adamson, C.J. Davis, Geert Barentsen, N.J. Wright

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We present initial results of the first panoramic search for high-amplitude near-infrared variability in theGalactic plane.We analyse the widely separated two-epoch K-band photometry in the fifth and seventh data releases of the UKIDSS Galactic plane survey.We find 45 stars with δK > 1 mag, including two previously known OH/IR stars and a Nova. Even though the midplane is not yet included in the data set, we find the majority (66 per cent) of our sample to be within known star-forming regions (SFRs), with two large concentrations in the Serpens OB2 association (11 stars) and the Cygnus-X complex (12 stars). Sources in SFRs show spectral energy distributions that support classification as young stellar objects (YSOs). This indicates that YSOs dominate the Galactic population of high-amplitude infrared variable stars at low luminosities and therefore likely dominate the total high-amplitude population. Spectroscopic follow up of the DR5 sample shows at least four stars with clear characteristics of eruptive premain- sequence variables, two of which are deeply embedded. Our results support the recent concept of eruptive variability comprising a continuum of outburst events with different timescales and luminosities, but triggered by a similar physical mechanism involving unsteady accretion. Also, we find what appears to be one of the most variable classical Be stars.
Original languageEnglish
Pages (from-to)1829-1854
Number of pages26
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Apr 2014


  • AGB and post-AGB-stars
  • Herbig Ae/Be-infrared
  • Low-mass-stars
  • Pre-main-sequence-stars
  • Protostars-stars
  • Stars
  • T Tauri
  • Variables


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