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arXiv · 1907.12050

The 2018 eruption and long term evolution of the new high-mass Herbig Ae/Be object Gaia-18azl = VES 263

U. Munari·V. Joshi·D. P. K. Banerjee·K. Cotar·Shugarov S. Y.·R. Jurdana-Sepic·R. Belligoli·A. Bergamini·M. Graziani·G. L. Righetti·A. Vagnozzi·P. Valisa
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Abstract

We have been monitoring, at high cadence, the photometric and spectroscopic evolution of VES 263 following the discovery in 2018 of a brightening labeled as event Gaia-18azl. VES 263 is so far a neglected emission-line object discovered in the 1960s on objective prism plates, tentatively classified as a semi-regular AGB cool giant by automated analysis of ASASSN lightcurves. We have discovered that VES 263 is a bonafide massive pre-Main Sequence object (~12 Msun), of the Herbig AeBe type. It is located at 1.68+/-0.07 kpc distance, within the Cyg OB2 star-forming region, and it is highly reddened (E(B-V)=1.80+/-0.05) by interstellar extinction. In quiescence, the spectral energy distribution is dominated by the 20,000 K photospheric emission from the central B1II star, and at wavelenghts >=6 micron by emission from circumstellar warm dust (Tdust up to 400 K). The 2018-19 eruption was caused by a marked brightening of the accretion disk around the B1II star as traced by the evolution with time of the integrated flux and the double-peaked profile of emission lines. At the peak of the eruption, the disk has a bulk temperature of ~7500 K and a luminosity L>=860 Lsun, corresponding to a mass accretion rate >=1.1x10(-5) Msun/yr. Spectroscopic signature of possible bipolar jets (at -700 and +700 km/s) of variable intensity are found. We have reconstructed from Harvard, Moscow and Sonneberg photographic plates the photometric history of VES 263 from 1896 to 1995, showing through 1953-1969 a state much brighter than current eruption.

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U. Munari, V. Joshi, D. P. K. Banerjee, K. Cotar, Shugarov S. Y., R. Jurdana-Sepic, R. Belligoli, A. Bergamini, M. Graziani, G. L. Righetti, A. Vagnozzi, P. Valisa. 2019-07-28. The 2018 eruption and long term evolution of the new high-mass Herbig Ae/Be object Gaia-18azl = VES 263. https://doi.org/10.1093/mnras%2Fstz2078

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