View source for Astronomy:PHL 293B

{{short description|Dwarf galaxy in the constellation of Aquarius}}
{{Sky|22|30|36.8|-|00|06|37}}
{{Infobox galaxy
| image = [[File:Color image of PHL 293B.tif|250px]]
| alt = PHL 293B
| caption = [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]] image of PHL 293B; the purported [[Astronomy:Luminous blue variable|luminous blue variable]] is located near the core of the galaxy
| credit = NASA, ESA/Hubble, J. Andrews (U. Arizona)
| epoch = [[Astronomy:J2000|J2000]]
| constellation name = [[Astronomy:Aquarius (constellation)|Aquarius]]
| ra = {{RA|22|30|36.8}}<ref name=Kehrig>{{cite journal|doi=10.1093/mnras/staa2299|arxiv=2009.11600|title=Mapping the ionized gas of the metal-poor H II galaxy PHL 293B with MEGARA|year=2020|last1=Kehrig|first1=C.|last2=Iglesias-Páramo|first2=J.|last3=Vílchez|first3=J. M.|last4=Gil De Paz|first4=A.|last5=Duarte Puertas|first5=S.|last6=Pérez-Montero|first6=E.|last7=Díaz|first7=A. I.|last8=Gallego|first8=J.|last9=Carrasco|first9=E.|last10=Cardiel|first10=N.|last11=García-Vargas|first11=M. L.|last12=Castillo-Morales|first12=A.|last13=Cedazo|first13=R.|last14=Gómez-Álvarez|first14=P.|last15=Martínez-Delgado|first15=I.|last16=Pascual|first16=S.|last17=Pérez-Calpena|first17=A.|journal=Monthly Notices of the Royal Astronomical Society|volume=498|issue=2|pages=1638–1650|url=https://eprints.ucm.es/id/eprint/63578/1/cardiel117preprint.pdf}}</ref>
| dec = {{DEC|-00|06|37}}<ref name=Kehrig/>
| h_radial_v = 
| z = 0.0051<ref name=Kehrig/>
| dist_ly = {{cvt|22.6|Mpc|Mly|lk=on|order=flip}}<ref name=kinman/>
| group_cluster = 
| type = Im?<ref name=Kehrig/>
| size = 
| appmag_v = 16.87<ref name=SIMBAD/>
| appmag_b = 17.35<ref name=SIMBAD/>
| absmag_v = 
| size_v = 
| names = {{odlist|name=Kinman's Dwarf|UGC=|MCG=|PGC=69018}}<ref name=SIMBAD>{{cite simbad|title=PHL 293B|accessdate=2021-08-30}}</ref>
}}
{{Starbox begin
|name=PHL 293B star}}
{{Starbox observe
| epoch = J1950
| constell = [[Astronomy:Aquarius (constellation)|Aquarius]]
| ra = {{RA|22|28.1}}<ref name=french1980>{{cite journal |bibcode=1980ApJ...240...41F |title=Galaxies with the spectra of giant H II regions |last1=French |first1=H. B. |journal=The Astrophysical Journal |year=1980 |volume=240 |page=41 |doi=10.1086/158205 |doi-access=free }}</ref>
| dec = {{DEC|-0|22}}<ref name=french1980/>
| appmag_v =
}}
{{Starbox character
| type = [[Astronomy:Luminous blue variable|Luminous blue variable]]?
| class =
| r-i =
| v-r =
| b-v =
| u-b =
| j-h =
| j-k =
| appmag_1_passband =
| appmag_1 =
| appmag_2_passband =
| appmag_2 =
| appmag_3_passband =
| appmag_3 =
| appmag_4_passband =
| appmag_4 =
| appmag_5_passband =
| appmag_5 =
| appmag_6_passband =
| appmag_6 =
| variable =
}}
{{Starbox astrometry
| radial_v = (of galaxy) 1,606<ref name=guseva2009>{{cite journal |doi=10.1051/0004-6361/200912414 |title=An investigation of the luminosity-metallicity relation for a large sample of low-metallicity emission-line galaxies |year=2009 |last1=Guseva |first1=N. G. |last2=Papaderos |first2=P. |last3=Meyer |first3=H. T. |last4=Izotov |first4=Y. I. |last5=Fricke |first5=K. J. |journal=Astronomy & Astrophysics |volume=505 |issue=1 |pages=63–72 |arxiv=0908.2539 |bibcode=2009A&A...505...63G |s2cid=17490296 }}</ref>
| prop_mo_ra =
| prop_mo_dec =
| parallax =
| p_error  =
| parallax_footnote =
| dist_ly  =
| dist_pc  = 22,600,000<ref name=kinman/>
| absmag_v =
}}
{{Starbox detail
| mass                   =
| radius                 = 1,348–1,463<ref name=allan/>
| luminosity             = 2,500,000–3,500,000<ref name=allan/>
| temperature            = 6,000–6,800<ref name=allan/>
| metal_fe               =
| rotational_velocity    =
| gravity                =
| age_myr                =
}}
{{Starbox catalog
| names    = SDSS&nbsp;J2230–0006,<ref name=izotov/> SDSS&nbsp;J223036.79-000636.9, A2228-00<ref name=terlevich/>
}}
{{Starbox reference
| Simbad = {{bracket|GPM2009}}+PHL293B |sn=PHL 293B
| Simbad2 = PHL+293 |sn2=PHL 293 (Simbad mistakenly showing results for PHL 293B)
}}
{{Starbox end}}

'''PHL 293B''', also known as '''Kinman's dwarf''', is a low-[[Astronomy:Metallicity|metallicity]] blue compact dwarf galaxy about 22.6 Mpc from the [[Astronomy:Earth|Earth]] in the constellation [[Astronomy:Aquarius (constellation)|Aquarius]].<ref name="kinman" />

It had a very likely associated, notable, blue-light, long-lived star with constant outbursts or a large [[Astronomy:Supernova|supernova]] observed to have faded and which then disappeared. Although this bright visible jet-producing object responsible for broad hydrogen emission lines with P Cygni profiles was widely considered to be a [[Astronomy:Luminous blue variable|luminous blue variable]] ejecting matter, other studies posited the mentioned, competing, explanations for the bright light source within.

==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.<ref name="hl">{{cite journal |bibcode=1962BOTT....3...37H |title=Faint Blue Stars in the Region near the South Galactic Pole |last1=Haro |first1=G. |last2=Luyten |first2=W. J. |journal=Boletín de los Observatorios de Tonantzintla y Tacubaya |year=1962 |volume=3 |page=37 }}</ref> In 1965, Thomas Kinman observed two faint possible companions to it, about {{val|1|ul='}} 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.<ref name="kinman">{{cite journal |bibcode=1965ApJ...142.1241K |title=The Nature of the Fainter Haro-Luyten Objects |last1=Kinman |first1=T. D. |journal=The Astrophysical Journal |year=1965 |volume=142 |page=1241 |doi=10.1086/148392 }}</ref><ref name="terlevich">{{cite journal |doi=10.1093/mnras/stu1806|title=High-velocity blueshifted Fe ii absorption in the dwarf star-forming galaxy PHL 293B: Evidence for a wind driven supershell?|year=2014|last1=Terlevich|first1=Roberto|last2=Terlevich|first2=Elena|last3=Bosch|first3=Guillermo|last4=Díaz|first4=Ángeles|last5=Hägele|first5=Guillermo|last6=Cardaci|first6=Mónica|last7=Firpo|first7=Verónica|s2cid=118457805|journal=Monthly Notices of the Royal Astronomical Society|volume=445|issue=2|pages=1449–1461|arxiv=1409.1189|bibcode=2014MNRAS.445.1449T}}</ref> 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.<ref name=french1980/> The galaxy was identified as a blue compact dwarf, a type of small [[Astronomy:Irregular galaxy|irregular galaxy]] undergoing a strong burst of star formation.<ref name="izotov">{{cite journal |bibcode=2009ApJ...690.1797I |title=Luminous Blue Variable Stars in the two Extremely Metal-Deficient Blue Compact Dwarf Galaxies DDO 68 and PHL 293B |last1=Izotov |first1=Yuri I. |last2=Thuan |first2=Trinh X. |s2cid=14150936 |journal=The Astrophysical Journal |year=2009 |volume=690 |issue=2 |pages=1797–1806 |doi=10.1088/0004-637X/690/2/1797 |arxiv=0809.3077 }}</ref>

The spectrum of PHL 293B is unusual both for its low [[Astronomy:Metallicity|metallicity]] and for broad hydrogen emission lines with P Cygni profiles. These are interpreted as being from a large [[Astronomy:Luminous blue variable|luminous blue variable]] star in the galaxy. The star is believed to have been undergoing an outburst during previous observations,<ref name=izotov/> an interpretation is disputed by some publications.{{citation needed|date=October 2020}} An alternative explanation would be a long-lived type IIn supernova, similar to the [[Astronomy:Transient astronomical event|transient event]] of SDSS1133.<ref name="burke">{{cite journal |bibcode=2020ApJ...894L...5B |title=The Curious Case of PHL 293B: A Long-lived Transient in a Metal-poor Blue Compact Dwarf Galaxy |last1=Burke |first1=Colin J. |last2=Baldassare |first2=Vivienne F. |last3=Liu |first3=Xin |last4=Foley |first4=Ryan J. |last5=Shen |first5=Yue |last6=Palmese |first6=Antonella |last7=Guo |first7=Hengxiao |last8=Herner |first8=Kenneth |last9=Abbott |first9=Tim M. C. |last10=Aguena |first10=Michel |last11=Allam |first11=Sahar |last12=Avila |first12=Santiago |last13=Bertin |first13=Emmanuel |last14=Brooks |first14=David |last15=Carnero Rosell |first15=Aurelio |last16=Carrasco Kind |first16=Matias |last17=Carretero |first17=Jorge |last18=Da Costa |first18=Luiz N. |last19=De Vicente |first19=Juan |last20=Desai |first20=Shantanu |last21=Doel |first21=Peter |last22=Eifler |first22=Tim F. |last23=Everett |first23=Spencer |last24=Frieman |first24=Josh |last25=García-Bellido |first25=Juan |last26=Gaztanaga |first26=Enrique |last27=Gruen |first27=Daniel |last28=Gruendl |first28=Robert A. |last29=Gschwend |first29=Julia |last30=Gutierrez |first30=Gaston |s2cid=211572824 |journal=The Astrophysical Journal |year=2020 |volume=894 |issue=1 |pages=L5 |doi=10.3847/2041-8213/ab88de |arxiv=2002.12369 |display-authors=29 |doi-access=free }}</ref> 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.<ref name="allan">{{Cite journal |bibcode = 2020MNRAS.496.1902A|title = The possible disappearance of a massive star in the low-metallicity galaxy PHL 293B|last1 = Allan|first1 = Andrew P.|last2 = Groh|first2 = Jose H.|last3 = Mehner|first3 = Andrea|last4 = Smith|first4 = Nathan|last5 = Boian|first5 = Ioana|last6 = Farrell|first6 = Eoin J.|last7 = Andrews|first7 = Jennifer E.|s2cid = 220302328|journal = Monthly Notices of the Royal Astronomical Society|year = 2020|volume = 496|issue = 2|page = 1902|doi = 10.1093/mnras/staa1629|arxiv = 2003.02242}}</ref>

==See also==
* [[Astronomy:AG Carinae|AG Carinae]]
* [[Astronomy:Markarian 177|Markarian 177]]
* [[Astronomy:LBV 1806-20|LBV 1806-20]]
* [[Astronomy:Eta Carinae|Eta Carinae]]

==References==
{{reflist}}

{{Stars of Aquarius}}
{{2020 in space}}

{{DEFAULTSORT:PHL 293B}}
[[Category:Aquarius (constellation)]]
[[Category:Dwarf galaxies]]
[[Category:SDSS objects]]
[[Category:Luminous blue variables]]

{{Sourceattribution|PHL 293B}}