The 2020 periastron passage of eta Carine seen in He I and He II lines

ATel #13508; Felipe Navarete (IAG/USP), Augusto Damineli (IAG/USP), Francisco Jablonski (DAS/INPE), Tim Brown (LCOGT), Markus Rabus (LCOGT)
on 20 Feb 2020; 14:13 UT
Credential Certification: Felipe Navarete (navarete@usp.br)

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In the framework of a monitoring campaign of the low excitation event (Damineli et a. 1998, A&A Supp. 133, 299) in eta Carinae, we report results on the periastron passage expected to occur on 2020 February 17 (Teodoro et al. 2016, ApJ 819:131). Optical spectra were collected on a daily basis using the NRES spectrometer at the 1-m telescopes of the Las Cumbres Observatory (CTIO-Chile and Sutherland-South Africa). Near-infrared spectra have been collected at the 1.6-m telescope of the Pico dos Dias Observatory (MCTIC/LNA/Br). The main result is that the period is compatible with 2022.7 days, with only minor changes in the line intensities as compared to previous events. The equivalent width (EW) of HeII 4686 reached its maximum intensity (named P2 peak) at about 2.5 weeks before periastron. The P2 peak is ~30% higher than the observed in the last periastron event (2014.6). Presently, the line is absent, but a new local peak (named P3) is expected for February 27th. On February 14th, the He I 10830A line reached the expected high-velocity absorption component (Groh et al. 2010, A&A 517, A9) extending up to -1860 Km/s and a P-Cygni absorption with an EW ~10% deeper than in the past event, confirming the trend already known. This is consistent with the existence of a dissipating coronagraph in front of the star (Damineli et al. 2019, MNRAS 484, 1325). This work is sponsored by FAPESP Foundation under projects 2019/02029-2 (AD) and 2017/18191-8 (FN).