The prototypical symbiotic star AX Persei is in outburst

ATel #17630; S. N. Shore (Univ. of Pisa, OATS-INAF); F. Teyssier (ARAS); F. Sims (ARAS); J. Hinnefeld (IUSB); D. Cujedo (ARAS)
on 26 Jan 2026; 02:26 UT
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Credential Certification: S. N. Shore (shore@df.unipi.it)

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The outburst started appears to have begun between 2026-01-13 and 01-18 (resp. JD 2461053.5 and +1058.6) at orbital phase 0.832 – 0.840 according to eclipse ephemeris (Skopal & al. , 2012 , 333, 242 DOI 10.1002/asna.201111655 ) . The V magnitude ros from 11.42 (JD+1053.5) to 10.92 (JD+1058.4) while B-V declined from 1.22 to 0.95. In flux calibrated spectra obtained by Sims (echelle R =10000, S/N ratio of 75 to 100 at the basis of H alpha) on JD+1052.6 and JD+1058.64, the most dramatic change is the collapse of high ionisation [Fe VII] 6086. Its flux (erg/s/cm^2) declined from 4.9(-13) to less than 4.2(-14) in less than 6 days (the line was still strong in a low resolution spectrum obtained by Hinnefeld on JD+ 1053.5) demonstrating a very short recombination time scale and implying a change in the soft XR continuum (around 0.15 keV) and a moderately high electron density. Flux calibrated spectra obtained by Cujedo (LISA spectrograph, R = 1000) were used to confirm the measures. The uncertainty on the velocities is about 10 km/s. The [O III] 4363, 4959,5007, [Ne III] 3869 increased significantly by a factor 3.4 and ~4, respectively. The low resolution secured by Hinnefeld (Alpy 600, R = 600) was used for the first measure. The ratio F([OIII] 5007/F([OIII] 6363) increased monotonically : 1.2, 1.7, 2.1 (JD +1052.5, +1058.64, +1061.1). The permitted lines H I Balmer, He II, and He I increased more moderately (by factors 1.5 for H beta, 1.8 for He II 4686, 2.4 for He I 5876 and 2.5 for He I 6678. The Balmer decrement didn’t significantly : 3.5 and 3.7 (JD +1052.5, +1061.1), corrected with E(B-V) = 0.27 (Mikolajewska & Kenyon 1992, AJ, 103, 579). The flux ratio [He II 4686]/[ H beta] was nearly constant: 1.2, 1.34, 1.14 (JD +1052.5, +1058.64, +1061.1). No significant change of the ratios of the flux of helium lines (triplet and singlet) is observed : He I 5876/He I 6678: 2.0, 1.9 at the same dates. The emission lines profiles changed substantially. This is well illustrated by He II, whose maximum redward radial velocity in the red increased from +139 to +253 km/s (JD +1052.5, +1061.5) in the rest frame of the system with the appearance of a bump in the red part. Similarly, the maximum red wing radial velocity of He I 5876 increased from +155 to +213 km/s. Similarly for [O III] 5007, 4959 whose maximum red wing radial velocity was +169 km/s ( JD+1061.5). The shape of [O III] 4363 differed significantly, the flux of red component being more intense than in [OIII] 5007. The [O III] ratio [4959+5007]/[4363] flux ratio, R ~1.5 (21-01-2026) corresponds to an electron density between 4E8/cmˆ3 (T_e ~2E4 K) and 3E9/ cmˆ3, similar to that implied by the [Fe VII] variations. The different profiles on the [O III] components sugests a density stratified medium. The profile [Ne III] 3869 (-113, +115 km/s), while showing the same components as [OIII], had a more symmetrical profile. Neither ] [N II] nor the Raman O VI lines were detected, N III 4640 showed well resolved narrow profiles for all components. Observations are continuing, further high resolution spectroscopy is urged; there should also be a notable change in the mid- and Far-UV and a decrease in the soft XRs. All spectra are available in the ARAS spectroscopic database : https://aras-database.github.io/database/axper.html

ARAS spectroscopic database