A descriptive title On the current quiescence status of the eruptive variable V1647 Ori

ATel #12054; T. Giannini, D. Lorenzetti, S. Antoniucci (INAF - Osservatorio Astronomico di Roma, Monte Porzio, Italy), W. Boschin, A. Harutyunyan (Telescopio Nazionale Galileo, La Palma, Spain)
on 21 Sep 2018; 11:08 UT
Credential Certification: Teresa Giannini (teresa.giannini@inaf.it)

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In the framework of our EXor monitoring program dubbed EXORCISM (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI, Lorenzetti et al. 2007 ApJ 665, 1182; Lorenzetti et al. 2009 ApJ 693, 1056), we recently observed V1647 Ori, an active low mass (0.8 Msun) eruptive variable in L1630 (D=400 pc), whose classification as FUor or EXor is still unclear. This is the reason why an accurate characterization of its outbursting/quiescence phases is in order. During its recent history, V1647 Ori underwent three documented outbursts of about 5 mag and 3 mag in the optical and IR bands, respectively. The 1st-one (detected on the Asiago plates) on 1966-67 (Aspin et al. 2006 AJ 132, 1298); the 2nd on 2004-06 (e.g. Acosta-Pulido et al. 2007 AJ 133, 2020 and references therein); the 3rd on 2008-2011 (e.g. Aspin 2011 AJ 142, 135 and references therein). These phases were followed by quiescence phases (Ojha et al. 2006 MNRAS 368, 825; Aspin et al. 2008 AJ 135, 423). In particular, a gradual fading has followed the last burst (Ninan et al. 2013, ApJ 778, 116). An absolute IR minimum was detected by 2MASS on 1998 Oct 7th. On 2018, Sept 3rd a deep minimum was registered by Semkov (ATEL #12012), who gives significant upper limits (R and I bands) compatible with a minimum fainter than the first drop observed on 2008 (Mosoni et al. 2013 A&A 552, 62). During the current quiescent phase, we have observed V1647 Ori on 2018 Sept 10th in the J,H, and K bands with the NICS IR camera at the 3.6m TNG Italian Telescope (La Palma, Canary Islands). Dithering was performed to cancel the nebular contribution. The following values have been obtained: J = 13.68±0.03, H = 11.88±0.03, and K = 9.73±0.05. Given the short temporal distance between the optical and IR recent observations (7 days), we could consider the R/I band upper limits (ATEL #12012), as associated to the same phase. At variance with the behavior of the optical R and I bands, in the IR regime the source appears brighter (specially in the J band) than what registered during the first fading. This circumstance could be related to a rapid increase of the extinction, or, more probably, to a brightening of the source occurred within few days. Remarkably, this last interpretation puts strong constraints on the timescale of the source fluctuations.