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The poorly studied variable star V390 Sco, previously classified as a Mira pulsator, was detected in a brightening event by the ESA Gaia satellite in September 2023. This work presents an analysis of available archival multifrequency photometric data of this target, along with our spectroscopic observations. Our findings lead to the conclusion that V390 Sco is a new symbiotic star identified by Gaia, currently undergoing a classical symbiotic outburst. Additionally, we uncovered three prior outbursts of this system through archival photometry. The outbursts recur approximately every 2330 - 2400 days, and we hypothesize the periastron passage in an eccentric orbit may trigger them, similarly to the case of BX Mon, DD Mic, or MWC 560. A detailed investigation into the nature of the donor star suggested that V390 Sco is an S-type symbiotic star, likely hosting a less evolved, semiregularly pulsating giant donor, but not a Mira variable., Comment: 9 pages, 9 figures, 1 table; accepted in Astronomische Nachrichten

On August 25th 2013 Dana Patchick from the "Deep Sky Hunters" (DSH) amateur astronomer group discovered a diffuse nebulosity in the Wide-field Infrared Survey Explorer (WISE) mid-IR image archive that had no optical counterpart but appeared similar to many Planetary Nebulae (PNe) in WISE. As his 30th discovery he named it Pa 30 and it was added to the HASH PN database as a new PN candidate. Little did he know how important his discovery would become. 10 years later this object is the only known bound remnant of a violent double WD merger accompanied by a rare Type Iax SN, observed and recorded by the ancient Chinese and Japanese in 1181 AD. This makes Pa 30 and its central star IRAS 00500+6713 (WD J005311) the only SN Iax remnant in our Galaxy, the only known bound remnant of any SN, and based on the central star's spectrum the only Wolf-Rayet star known that neither has a massive progenitor nor is the central star of a Planetary Nebula. We cover this story and our key role in it., Comment: 6 pages, 5 figures, 1 table, submitted to IAU 384 conference proceedings

Planets grow in rotating disks of dust and gas around forming stars, some of which can subsequently collide in giant impacts after the gas component is removed from the disk. Monitoring programs with the warm Spitzer mission have recorded significant and rapid changes in mid-infrared output for several stars, interpreted as variations in the surface area of warm dusty material ejected by planetary-scale collisions and heated by the central star: e.g., NGC 2354-ID8, HD 166191 and V844 Persei. Here we report combined observations of the young (about 300 Myr), solar-like star ASASSN-21qj: an infrared brightening consistent with a blackbody temperature of 1000 K and a luminosity of 4 percent of that of the star lasting for about 1000 days, partially overlapping in time with a complex and deep wavelength-dependent optical eclipse that lasted for about 500 days. The optical eclipse started 2.5 years after the infrared brightening, implying an orbital period of at least that duration. These observations are consistent with a collision between two exoplanets of several to tens of Earth masses at 2 to 16 au from the central star. Such an impact produces a hot, highly-extended post-impact remnant with sufficient luminosity to explain the infrared observations. Transit of the impact debris, sheared by orbital motion into a long cloud, causes the subsequent complex eclipse of the host star., Comment: 28 pages, 9 figures, 2 tables, author's Accepted Manuscript version, reproducible workflow built with showyourwork; open-source code can be found at https://github.com/mkenworthy/ASASSN-21qj-collision/

We present evidence that the nebular cocoon and bow-shock emission nebula putatively and recently reported as deriving from the 9th magnitude "runaway" star HD 185806 is the previously discovered but obscure planetary nebula WHTZ 1 (Ra 7). It has a Gaia DR3 G~16 blue ionizing star at its geometric centre. We present imagery, spectroscopy, other data and arguments to support that this emission source is a high excitation Planetary Nebula not a stellar wind bow shock., Comment: 8 pages, 6 figure, accepted for publication in MNRAS

In this work, we present the discovery and characterization of a new southern S-type symbiotic star, DeGaPe 35. We have obtained the low-resolution spectroscopic observations and supplemented them with photometry from Gaia DR3 and other surveys. The optical spectra of this target show prominent emission lines, including highly ionized [Fe VII] and O VI lines. The cool component of this symbiotic binary is an M4-5 giant with effective temperature ~ 3 380 - 3 470 K and luminosity ~ 3 000 L$_\odot$ (for the adopted distance of 3 kpc). The hot component is a shell-burning white dwarf. The photometric observations of the Gaia satellite, published recently in the Gaia DR3 suggested the variability with the period of about 700 - 800 days that we tentatively attributed to the orbital motion of the binary., Comment: accepted for publication in New Astronomy; 7 pages, 5 figures, 1 table

We report observations and modeling of the stellar remnant and presumed double-degenerate merger of Type~Iax supernova Pa30, which is the probable remnant of SN~1181~AD. It is the only known bound stellar SN remnant and the only star with Wolf-Rayet features that is neither a planetary nebula central star nor a massive Pop I progenitor. We model the unique emission-line spectrum with broad, strong O~{\sc vi} and O~{\sc viii} lines as a fast stellar wind and shocked, hot gas. Non-LTE wind modeling indicates a mass-loss rate of $\sim 10^{-6}\,\rm M_\odot\,yr^{-1}$ and a terminal velocity of $ \sim$15,000~km\,s$^{-1}$, consistent with earlier results. O~{\sc viii} lines indicate shocked gas temperatures of $T \simeq 4\,$MK. We derive a magnetic field upper limit of $B<2.5\,$MG, below earlier suggestions. The luminosity indicates a remnant mass of 1.0--1.65\,\rm M$_\odot$ with ejecta mass $0.15\pm0.05\,\rm M_\odot$. Archival photometry suggests the stellar remnant has dimmed by $\sim$0.5 magnitudes over 100 years. A low Ne/O$\,<0.15$ argues against a O-Ne white dwarf in the merger. A cold dust shell is only the second detection of dust in a SN Iax and the first of cold dust. Our ejecta mass and kinetic energy estimates of the remnant are consistent with Type Iax extragalactic sources., Comment: 20 pages, 13 figures, 3 tables. Matches version accepted for publication by ApJ

The guest star of AD 1181 is the only historical supernova of the last millennium that is without a definite counterpart. The previously proposed association with supernova remnant 3C58 is in strong doubt because of the inferred age of this remnant. Here we report a new identification of SN 1181 with our codiscovery of the hottest known Wolf Rayet star of the Oxygen sequence (dubbed Parkers star) and its surrounding nebula Pa 30. Our spectroscopy of the nebula shows a fast shock with extreme velocities of approx. 1,100kms. The derived expansion age of the nebula implies an explosive event approx 1,000 years ago which agrees with the 1181 AD event. The on sky location also fits the historical Chinese and Japanese reports of SN 1181 to 3.5degrees. Pa 30 and Parkers star have previously been proposed to be the result of a double-degenerate merger, leading to a rare Type Iax supernova. The likely historical magnitude and the distance suggest the event was subluminous for normal supernova. This agrees with the proposed Type Iax association which would also be the first of its kind in the Galaxy. Taken together, the age, location, event magnitude and duration elevate Pa 30 to prime position as the counterpart of SN 1181. This source is the only Type Iax supernova where detailed studies of the remnant star and nebula are possible. It provides strong observational support for the double degenerate merger scenario for Type Iax supernovae., Comment: 9 pages, 3 figures, 1 table

We present the discovery of 6 nebular objects made by amateur astronomers. Four of these discoveries are clearly planetary nebulae (PNe), one is a possible PN, and another is a likely H II region. The bipolar nebula Ou4 presents the largest angular extent ever found : over one degree on the sky! We consider various scenarios that could explain such a nebula. Ou4 could be one of the nearest PNe known, though its possible PN nature will need confirmation., Comment: Accepted by Rev.Mex.AA; 18 pages,8 figures