That's excellent
The ATel, writtren by Jaroslav and Rudolf,
http://www.astronomerstelegram.org/?read=12660
The symbiotic star AX Per is going into strong outburst
ATel #12660; J. Merc (UPJS in Kosice, Charles University), R. Galis (UPJS in Kosice), F. Teyssier, D. Boyd, W. Sims, C. Boussin, F. Campos (ARAS)
on 13 Apr 2019; 11:21 UT
Credential Certification: Jaroslav Merc (
jaroslav.merc@student.upjs.sk)
Subjects: Optical, Request for Observations, Cataclysmic Variable, Transient, Variables
AX Per is a well-known eclipsing symbiotic binary consisting of a giant of type M4.5 III (Muerset & Schmid 1999, A&AS, 137, 473) and probably a white dwarf. The orbital period of the binary system is around 680 days (Mikolajewska & Kenyon 1992, AJ, 103, 579). The light curve of AX Per is characterized by the wave-like variations whose shape is changing from cycle to cycle. After major outbursts of the system in 1988-1992, a new activity stage has begun in 2007, with minor outbursts observed in 2009, 2010, 2012 and 2014 (Munari & Siviero 2009, CBET, No. 1757; Munari , Siviero, et al. 2010, CBET, No. 2555; ATel #4265, ATel #6382). All recent outbursts were significantly lower in magnitude (maximal V around 10) than the major outbursts in 90s (with V < 9). In this Astronomer's Telegram, we report the beginning of a new outburst of AX Per with a strong increase in brightness. In the previous orbital cycle, the brightness of the symbiotic system reached the maximum of B=11.589 and V=10.873 (October 15, 2017; JD 2458042.319). During the binary eclipse in August/September 2018, the magnitudes decreased to the minimum of B=13.387 and V=12.355 on August 21, 2018 (JD 2458352.375). Since then, the brightness of AX Per has started to increase and the March 2019 measurements have shown that it has reached a similar level or was higher than the previous maximum of B=11.516 and V=10.652 (March 24, 2019; JD 2458567.330). Our observation obtained on April 10, 2019 (JD 2458584.337) indicate that the AX Per brightness continues to rise (B=11.109 and V=10.330) in what looks like a promising major outburst of this symbiotic binary. The low resolution spectroscopic observations (R < 1000) obtained during March and April 2019 showed significant changes in the prominent emission lines and in the continuum compared to the spectra acquired at the end of 2018. We note the disappearance of the highly ionized lines (e. g. [Fe VII]) or the change of the He I singlet/triplet ratio. Several emission lines of the He I which were not observable are fairly strong in the recent spectra, and similar behavior is observed in the case of Fe II lines. The Balmer lines equivalent widths have also increased significantly (1.3 times since December 2018). Nebular-to-auroral line ratio of [OIII] 5007/4363 has increased from 0.7 to 1.6. This behavior points to a classical symbiotic outburst during which a accreting layer on white dwarf expands and cools down. We will continue the photometric and spectroscopic monitoring of the AX Per current outburst. It will be interesting to see if the outburst is another of a series of minor outbursts, or we will finally observe a major outburst of this symbiotic system. Recent spectroscopic observations could be found in the ARAS Spectral Database (link to the database below).
ARAS Spectral Database