Reappearance of the recurrent CH3OH flares at -1 km/s in Cep A HW2

ATel #17027; Pawel Wolak, Michal Durjasz, Ashwin Varma, Marian Szymczak, Anna Bartkiewicz (Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland)
on 11 Feb 2025; 13:36 UT
Credential Certification: Pawel Wolak (wolak@astro.uni.torun.pl)

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Torun radio telescope detected the first moments of a rapid 6.7GHz flare of methanol maser emission in Cepheus A HW2. As predicted by Durjasz et al. (2022), the burst in the extremely red-shifted part of the spectrum, near the LSR velocity of -1.1 km/s, has reappeared after 5 years (http://paulo.astro.umk.pl/~pw/ATEL3/fig1.html). Current activity reappeared with an accuracy of 12 days (2025 Feb 3), assuming a mean period of 1829+/-22 days, i.e. 5 years and 3 days, that was calculated based on current and three previously detected bursts (http://paulo.astro.umk.pl/~pw/ATEL3/fig2.html). The flaring emission was pinpointed at the edge of a dust disc reported by Patel et al. (2005)(Sanna et al. 2017, Durjasz et al. 2022) (http://paulo.astro.umk.pl/~pw/ATEL3/fig3.html). Previous observed flares lasted for 150 - 500 days, where 150 is likely to be biased due to RFI. We expect the flare to last for about ~400 days. We acknowledge support from the National Science Centre, Poland, through grant 2021/43/B/ST9/02008. The 32 m radio telescope is operated by the Institute Astronomy, Nicolaus Copernicus University and supported by the Polish Ministry of Science and Higher Education SpUB grant.