Near-infrared monitoring of the accretion outburst in the massive young stellar object S255-NIRS3. (20th November 2019)

• Record Type: Journal Article
• Authors: Uchiyama, Mizuho; Yamashita, Takuya; Sugiyama, Koichiro; Nakaoka, Tatsuya; Kawabata, Miho; Itoh, Ryosuke; Yamanaka, Masayuki; Akitaya, Hiroshi; Kawabata, Koji; Yonekura, Yoshinori; Saito, Yu; Motogi, Kazuhito; Fujisawa, Kenta
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 72:Number 1(2020:Feb.)
• Publication Date: 2019-11-20
• Subjects: stars: formation -- stars: individual (S255-NIRS3) -- stars: massive -- stars: variables: general; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psz122
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: We followed up the massive young stellar object S255-NIRS3 (= S255-IRS1b) during its recent accretion outburst event in the $K_{\rm s}$ band with Kanata/HONIR for four years after its burst and obtained a long-term light curve. This is the most complete near-infrared light curve of the S255-NIRS3 burst event that has ever been presented. The light curve showed a steep increase reaching a peak flux that was 3.4 mag brighter than the quiescent phase and then a relatively moderate year-scale fading until the last observation, similar to that of the accretion burst events such as EXors found in lower-mass young stellar objects. The behavior of the $K_{\rm s}$ -band light curve is similar to that observed in 6.7 GHz class II methanol maser emission, with a sudden increase followed by moderate year-scale fading. However, the maser emission peaks appear 30–50 d earlier than that of the $K_{\rm s}$ band emission. The similarities confirmed that the origins of the maser emission and the $K_{\rm s}$ -band continuum emission are common, as previously shown from other infrared and radio observations by Stecklum et al. (2016, Astronomer's Telegram, 8732), Caratti o Garatti et al. (2017b, Nature Phys., 13, 276), and Moscadelli et al. (2017, A&A, 600, L8). However, the differences in energy transfer paths, such as the exciting/emitting/scattering structures, may cause the delay in the flux-peak dates.