PHL 293B

PHL 293B is a low-metallicity blue compact dwarf galaxy. The name is also used to refer to a possible outburst and/or supernova imposter star observed to have disappeared from the galaxy.

PHL 293B
Observation data
Epoch J1950      Equinox J1950
Constellation Aquarius
Right ascension  22h 28.1m[1]
Declination −0° 22′[1]
Characteristics
Evolutionary stage Luminous blue variable?
Astrometry
Details
Other designations
Kinman's dwarf,[2] SDSS J2230–0006,[3] SDSS J223036.79-000636.9, A2228-00[2]
Database references
SIMBADPHL 293B
PHL 293 (Simbad mistakenly showing results for PHL 293B)

Currently, scientists are still puzzled, and are unsure about whether this star even exists. At the moment, considered a luminous blue variable star.

Observation History

PHL 293 was first listed as entry 293 in a catalogue of faint blue stars published by Guillermo Haro and Willem Jacob Luyten in 1962.[4] In 1965, Thomas Kinman observed two faint companions to HL 293, about 1′ away, and called them A and B. HL 293 B was noted to be non-stellar, including a jet. Its redshift was measured and it was estimated to be an extragalactic object 22.6 MPc away.[5] It is sometimes called Kinman's Dwarf.[2] The acronym PHL has been applied since to distinguish from other HL catalogues and it is most commonly referred to by astronomers as PHL 293 B.[1] The galaxy was identified as a blue compact dwarf, a type of small irregular galaxy undergoing a strong burst of star formation.[3]

The spectrum of PHL 293B is unusual both for its low metallicity and for broad hydrogen emission lines with P Cygni profiles. The emission lines are interpreted as being from a single luminous blue variable star within the galaxy which was undergoing an outburst,[3] although this is disrupted by other publications. One alternative explanation would be a long-lived type IIn supernova.[6] These emission features in the spectrum of the galaxy faded during 2019 and by the end of the year had disappeared.[7]

Its disappearance was published in 2020.[8] The star in question is currently under surveillance, as astronomers scour space in search for it.

See also

References
  1. French, H. B. (1980). "Galaxies with the spectra of giant H II regions". The Astrophysical Journal. 240: 41. Bibcode:1980ApJ...240...41F. doi:10.1086/158205.
  2. Terlevich, Roberto; Terlevich, Elena; Bosch, Guillermo; Díaz, Ángeles; Hägele, Guillermo; Cardaci, Mónica; Firpo, Verónica (2014). "High-velocity blueshifted Fe ii absorption in the dwarf star-forming galaxy PHL 293B: Evidence for a wind driven supershell?". Monthly Notices of the Royal Astronomical Society. 445 (2): 1449–1461. arXiv:1409.1189. Bibcode:2014MNRAS.445.1449T. doi:10.1093/mnras/stu1806. S2CID 118457805.
  3. Izotov, Yuri I.; Thuan, Trinh X. (2009). "Luminous Blue Variable Stars in the two Extremely Metal-Deficient Blue Compact Dwarf Galaxies DDO 68 and PHL 293B". The Astrophysical Journal. 690 (2): 1797–1806. arXiv:0809.3077. Bibcode:2009ApJ...690.1797I. doi:10.1088/0004-637X/690/2/1797. S2CID 14150936.
  4. Haro, G.; Luyten, W. J. (1962). "Faint Blue Stars in the Region near the South Galactic Pole". Boletin de los Observatorios Tonantzintla y Tacubaya. 3: 37. Bibcode:1962BOTT....3...37H.
  5. Kinman, T. D. (1965). "The Nature of the Fainter Haro-Luyten Objects". The Astrophysical Journal. 142: 1241. Bibcode:1965ApJ...142.1241K. doi:10.1086/148392.
  6. 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. S2CID 211572824.
  7. Allan, Andrew P.; Groh, Jose H.; Mehner, Andrea; Smith, Nathan; Boian, Ioana; Farrell, Eoin J.; Andrews, Jennifer E. (2020). "The possible disappearance of a massive star in the low-metallicity galaxy PHL 293B". Monthly Notices of the Royal Astronomical Society. 496 (2): 1902. arXiv:2003.02242. Bibcode:2020MNRAS.496.1902A. doi:10.1093/mnras/staa1629. S2CID 220302328.
  8. "Massive Variable Star Mysteriously Disappears from Distant Dwarf Galaxy | Astronomy | Sci-News.com". Breaking Science News | Sci-News.com.
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