Extreme infrared variables from UKIDSS – II. An end-of-survey catalogue of eruptive YSOs and unusual stars

• Published in: Monthly notices of the Royal Astronomical Society Vol. 472; no. 3; pp. 2990 - 3020
• Main Authors: Lucas, P. W., Smith, L. C., Contreras Peña, C., Froebrich, D., Drew, J. E., Kumar, M. S. N., Borissova, J., Minniti, D., Kurtev, R., Monguió, M.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.12.2017
• Subjects: Accretion; Amplitudes; Binary stars; Cataclysmic variables; Deposition; H II regions; Infrared astronomy; Infrared stars; Mira variables; Nebulae; Star formation; Variable stars; Variables; Wide-field Infrared Survey Explorer; North America; stars: AGB and post-AGB; stars: variables: T Tauri, Herbig Ae/Be; galaxies: active; novae, cataclysmic variables – stars: protostars
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx2058

Abstract We present a catalogue of 618 high-amplitude infrared variable stars (1 < ΔK < 5 mag) detected by the two widely separated epochs of 2.2 μm data in the UKIDSS Galactic plane survey, from searches covering ∼1470 deg2. Most were discovered by a search of all fields at 30 < l < 230°. Sources include new dusty Mira variables, three new cataclysmic variable candidates, a blazar and a peculiar source that may be an interacting binary system. However, ∼60 per cent are young stellar obbjects (YSOs), based on spatial association with star-forming regions at distances ranging from 300 pc to over 10 kpc. This confirms our initial result in Contreras Peña et al. (Paper I) that YSOs dominate the high-amplitude infrared variable sky in the Galactic disc. It is also supported by recently published VISTA Variables in the Via Lactea (VVV) results at 295 < l < 350°. The spectral energy distributions of the YSOs indicate class I or flat-spectrum systems in most cases, as in the VVV sample. A large number of variable YSOs are associated with the Cygnus X complex and other groups are associated with the North America/Pelican nebula, the Gemini OB1 molecular cloud, the Rosette complex, the Cone nebula, the W51 star-forming region and the S86 and S236 H ii regions. Most of the YSO variability is likely due to variable/episodic accretion on time-scales of years, albeit usually less extreme than classical FUors and EXors. Luminosities at the 2010 Wide-field Infrared Survey Explorer epoch range from ∼0.1 to 103 L⊙ but only rarely exceed 102.5 L⊙.