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We present the results of a search for extended emission-line regions (EELRs) ionized by extant or recently faded active galactic nuclei (AGNs), using [O III] narrow-band imaging and spectroscopic follow-up. The sample includes 198 galaxies in 92 strongly interacting or merging galaxy systems in the range of z = 0.009–0.0285. Among these, three systems have EELRs extended beyond 10 kpc in projection from the nucleus detected in previous studies. We identify a single new distant emission region, projected 35 kpc from UGC 5941. Our optical spectrum does not detect He II, but its strong-line ratios put this in the same class as securely characterized EELR clouds. The nucleus of UGC 5941 is dominated by recent star formation, preventing detection of any weak ongoing AGN. Overall counts of distant EELRs in this and the previous TELPERION samples give incidence 2–5 per cent depending on galaxy and AGN selection, 20–50 times higher than the Galaxy Zoo EELR survey with its higher surface-brightness threshold and much larger input sample. AGNs in interacting and merging systems have an increased detection rate of 12 ± 6 per cent, while none are detected around non-interacting AGNs. Some of these AGNs are at luminosity low enough to require additional X-ray or far-infrared information to tell whether the EELR ionization level suggests long-term fading.

 

The similarity in physical conditions in the winds of low-mass post-asymptotic giant branch stars and evolved massive stars leads to the appearance of an interesting phenomenon of spectral mimicry. Because of this, the discovery of every new star with a Wolf–Rayet (WR) spectrum requires a special study of its evolutionary status before it can be included in the list of Galactic WR stars. A couple of years ago, LAMOST J040901.83+323955.6 (hereafter J0409+3239) was selected as a WR star in the LAMOST spectroscopic data base by machine-learning methods. In this work, we investigate its evolutionary status. After analysing the spatial location of J0409+3239  in the Galaxy and its position in the colour–magnitude diagram, we conclude that J0409+3239  is instead a low-mass object displayng the WR phenomenon. Its luminosity is $L*=1000~\rm L_\odot$ and its effective temperature is Teff = 40 000 K. Using new and archival photometric data, we detected irregular variability on time-scales from hours to tens of days with an amplitude of up to ~0.2 mag. A comparison of the spectrum obtained in 2022 with that from 2014 also shows evidence of spectral variability. The absence of a clearly detected circumstellar nebula prevents the classification of J0409+3239  as [WR], namely as the central star of a planetary nebula (CSPN). However, the position of J0409+3239 on the Hertzsprung–Russell diagram suggests that this object  is a low-mass star caught in a rare transitional phase to CSPN. Estimation of the J0409+3239  mass based on evolutionary tracks shows that it is less than $0.9~\rm M_\odot$, and thus that the age of the Galaxy is barely sufficient for the star to have evolved to its current stage.

 

We present Chandra X-ray Observatory observations and Space Telescope Imaging Spectrograph spectra of NGC 5972, one of the 19 ‘Voorwerpjes’ galaxies. This galaxy contains an extended emission-line region (EELR) and an arcsecond scale nuclear bubble. NGC 5972 is a faded active galactic nucleus (AGN), with EELR luminosity suggesting a 2.1 dex decrease in Lbol in the last ∼5 × 104 yr. We investigate the role of AGN feedback in exciting the EELR and bubble given the long-term variability and potential accretion state changes. We detect broad-band (0.3–8 keV) X-ray emission in the near-nuclear regions, coincident with the [O iii] bubble, as well as diffuse soft X-ray emission coincident with the EELR. The soft nuclear (0.5–1.5 keV) emission is spatially extended and the spectra are consistent with two apec thermal populations (∼0.80 and ∼0.10 keV). We find a bubble age >2.2 Myr, suggesting formation before the current variability. We find evidence for efficient feedback with $P_{\textrm {kin}}/L_{\textrm {bol}}\sim 0.8~{{\ \rm per\ cent}}$, which may be overestimated given the recent Lbol variation. [O iii] kinematics show a 300 km s−1 high-ionization velocity consistent with disturbed rotation or potentially the line-of-sight component of a ∼780 km s−1 thermal X-ray outflow capable of driving strong shocks to photoionize the precursor material. We explore possibilities to explain the overall jet, radio lobe and EELR misalignment including evidence for a double supermassive black hole which could support a complex misaligned system.

 

ABSTRACT Motivated by the discovery of large ionized clouds around AGN, and particularly the large fraction of those that are consistent with photoionized gaseous tidal debris, we searched for [O iii] emission around Seyfert galaxies previously mapped in H i, many with extended gas features. Of 26 Seyfert galaxies, we find one spatially extended emission feature, a discrete cloud projected ≈12 kpc SW from the centre of Mkn 1 and spanning a transverse extent of 8 kpc. Optical spectroscopy (Kast/Lick and SCORPIO/BTA) of this cloud confirms its association with the Mkn 1–NGC 451 galaxy pair, closely matching the kinematics of nearby H i structures, and reveals emission-line ratios requiring photoionization by the AGN at roughly the direct observed luminosity of the nucleus. For the entire sample, the full opening angle of the ionization cones (bicones) must be <20° if the AGNs are continuously bright for scales longer than the light-traveltimes to the H i structures. Since typical AGN ionization cones are observed to be much broader than this, our low detection fraction may add to evidence for the ubiquity of strong variations in AGN luminosity on scales 104–105 yr.