It had a very likely associated, notable, blue-light, long-lived star with constant outbursts or a largesupernova observed to have faded and which then disappeared. Although this bright visible jet-producing object responsible for broad hydrogenemission lines withP Cygni profiles was widely considered to be aluminous blue variable ejecting matter, other studies posited the mentioned, competing, explanations for the bright light source within.
PHL 293 was first listed as entry293 in a catalogue of faint blue stars published byGuillermo Haro andWillem Jacob Luyten in 1962.[9] In 1965, Thomas Kinman observed two faint possible companions to it, about1′ away, which he dubbed A and B. HL 293B, sometimes called Kinman's Dwarf, was noted to be an extragalactic, nonstellar object, with a jet, approximately 22.6 Mpc away from Earth.[2][8] The acronym PHL has since been applied to distinguish it from other HL catalogues; it is most commonly referred to by astronomers as PHL 293B.[4] The galaxy was identified as ablue compact dwarf, a type of smallirregular galaxy undergoing a strong burst of star formation.[7]
The spectrum of PHL 293B is unusual both for its lowmetallicity and for broad hydrogenemission lines withP Cygni profiles. These are interpreted as being from a largeluminous blue variable star in the galaxy. The star is believed to have been undergoing an outburst during previous observations,[7] an interpretation is disputed by some publications.[citation needed] An alternative explanation would be a long-livedtype IIn supernova, similar to thetransient event ofSDSS1133.[10] These emission features in the spectrum of the galaxy faded during 2019 and by the end of the year had disappeared (at least visibly), likely due to the disappearance of a bright star of the galaxy.[6]
^abcdKehrig, C.; Iglesias-Páramo, J.; Vílchez, J. M.; Gil De Paz, A.; Duarte Puertas, S.; Pérez-Montero, E.; Díaz, A. I.; Gallego, J.; Carrasco, E.; Cardiel, N.; García-Vargas, M. L.; Castillo-Morales, A.; Cedazo, R.; Gómez-Álvarez, P.; Martínez-Delgado, I.; Pascual, S.; Pérez-Calpena, A. (2020)."Mapping the ionized gas of the metal-poor H II galaxy PHL 293B with MEGARA"(PDF).Monthly Notices of the Royal Astronomical Society.498 (2):1638–1650.arXiv:2009.11600.doi:10.1093/mnras/staa2299.
^Haro, G.; Luyten, W. J. (1962). "Faint Blue Stars in the Region near the South Galactic Pole".Boletín de los Observatorios de Tonantzintla y Tacubaya.3: 37.Bibcode:1962BOTT....3...37H.
^Burke, Colin J.; Baldassare, Vivienne F.; Liu, Xin; Foley, Ryan J.; Shen, Yue; Palmese, Antonella; Guo, Hengxiao; Herner, Kenneth; Abbott, Tim M. C.; Aguena, Michel; Allam, Sahar; Avila, Santiago; Bertin, Emmanuel; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Da Costa, Luiz N.; De Vicente, Juan; Desai, Shantanu; Doel, Peter; Eifler, Tim F.; Everett, Spencer; Frieman, Josh; García-Bellido, Juan; Gaztanaga, Enrique; Gruen, Daniel; Gruendl, Robert A.; Gschwend, Julia; et al. (2020)."The Curious Case of PHL 293B: A Long-lived Transient in a Metal-poor Blue Compact Dwarf Galaxy".The Astrophysical Journal.894 (1): L5.arXiv:2002.12369.Bibcode:2020ApJ...894L...5B.doi:10.3847/2041-8213/ab88de.S2CID211572824.
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