Slow ASAS-SN optical brightening of the massive LMC double Wolf-Rayet star binary R144=HD38282

ATel #18094; Andy Pollock (University of Sheffield, UK), Paul Crowther (University of Sheffield, UK)
on 8 Oct 2026; 11:15 UT
Credential Certification: Andrew Pollock (a.m.pollock@sheffield.ac.uk)

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R144 = HD38282 is a very massive binary system of two Wolf-Rayet stars classified WN5/6h and WN6/7h and one of the brightest stars in the LMC. Some years ago, ASAS-SN data were the source of the recognition of its binary period of 74 days and the complicated form of its folded light curve that displays one short and one long eclipse and a maximum close to the periastron of its eccentric orbit. ASAS-SN has routinely been delivering g-band filter measurements of R144 every few days since late 2017. Until mid-2023, the g-band data showed repeated binary modulations about a mean magnitude near 11.0. Since mid-2023, according to ASAS-SN, the g-band magnitude has been increasing although still subject to the same binary modulation. The form of the final two orbital cycles in 2025 were also observed in sectors 97 and 98 by TESS retrieved through MAST and are in agreement regarding the modulation. ASAS-SN project personnel have kindly reviewed the material downloaded through their Sky Patrol website and did not identify any instrumental issues which might account for the apparent brightening. The system is now about 0.3 magnitudes brighter and continues to increase. We encourage photometric and spectroscopic observers firstly to confirm and then possibly to enrich this developing event in a special binary system in the LMC. For example, several more TESS sectors are available for which normalised measurements could test the long-term behaviour reported here.