AP Librae

{{Short description|Active galactic nucleus in the constellation Libra}} {{Infobox quasar | name = AP Librae | image = APLibLightCurve.png | caption = [[Light curve]]s for AP Librae. Top panel: The long-term variability, plotted from data published by Fan & Lin (2000).<ref name="Fan_2000"/> Bottom panel: short-timescale variability, adapted from Carini ''et al.'' (1991)<ref name="Carini_1991"/> | epoch = [[J2000]] | ra = {{RA|15|17|41.814}}<ref name=GaiaEDR3/> | dec = {{DEC|−24|22|19.48}}<ref name=GaiaEDR3/> | constellation name = [[Libra (constellation)|Libra]] | z = 0.049<ref name=Roychowdhury_et_al_2022/> | dist_pc = | dist_ly = {{cvt|215|Mpc|Mly|order=flip|lk=on}}<ref name=Sanchez_et_al_2015/> | type = [[BL Lac object|BL Lac]]<ref name=Visvanathan_Griersmith_1977/> | appmag_v = 14.0<ref name=Ducati2002/> | size_v = {{nowrap|0′.323 × 0′.278}}<ref name=Skrutskie_et_al_2006/> | notes = Highly active; emits a one-sided radio [[Astrophysical jet|jet]] | names = {{odlist | V=AP Lib | LEDA=54592 }}, PKS 1514-24, QSO B1514-24<ref name=SIMBAD/> }}

'''AP Librae''' is a [[BL Lacertae object]]<ref name=Visvanathan_Griersmith_1977/> located at a distance of 700 million [[light year]]s<ref name=Sanchez_et_al_2015/> in the southern [[constellation]] of [[Libra (constellation)|Libra]]. In the visual [[Electromagnetic band|band]] it is one of the most active [[blazar]]s known.<ref name=Kaufmann_et_al_2013/> AP Lib is surrounded by an extended source with a [[stellar spectrum|spectrum]] characteristic of a [[Redshift|red-shifted]] [[giant elliptical galaxy]]. The derived [[visual magnitude]] of this region is 15.0, and it follows a radially decreasing brightness that is characteristic of an elliptical. Seven fainter galaxies are visible within an angular radius of {{val|9|ul=arcminute}}, suggesting it is the brightest member of a [[galactic cluster]].<ref name=Visvanathan_Griersmith_1977/>

This object was first identified as an optical [[Variable star|variable]] by Martha D. Ashbrook in 1942, who noted the brightness changed irregularly from magnitude 15.0 down to 16.0.<ref name=Bond1971/> The source was found to vary chaotically on time scales of days and even hours.<ref name=Hunstead1971/> Howard E. Bond and Francois Biraud in 1971 noted the coincidence of this object with the position of the [[Astronomical radio source|radio source]] PKS 1514–24.<ref name=Andrews_et_al_1974/> In 1965, [[John Gatenby Bolton|John G. Bolton]] and associates identified the latter as a sixteenth magnitude [[elliptical galaxy]].<ref name=Bond1971/> Glenn M. Frye and associates in 1971 suggested that it may be a [[Gamma-ray astronomy|gamma-ray]] source.<ref name=Andrews_et_al_1974/> The similarity of this object to [[BL Lacertae]] was noted, leading to it being designated as a BL Lac object.<ref name=Peterson_et_al_1976/>

AP Librae emits a [[synchrotron radiation]] component to its [[spectral energy distribution]] (SED). The peak component of this radiation lies in the [[infrared astronomy|infrared]] band, making this a low-frequency peaked BL Lac (LBL). It is one of the few LBLs known to emit gamma rays. The width of the high energy component of the SED is considered extremely broad for objects of this class, ranging in energy from around {{val|0.1|ul=keV}} up to the TeV level.<ref name=Fortin_et_al_2010/> In 1998–99, extended radio emission was detected from a one-sided [[Astrophysical jet|jet]] that starts in a south-easterly direction from the source before bending to the northeast.<ref name=Cassaro_et_al_1999/> This non-thermal jet extends {{val|15|ul=arcsecond}} from AP Lib (equivalent to ~{{cvt|14|kpc|kly|disp=out|lk=on}}), and in 2013 was found to emit [[X-ray astronomy|X-rays]].<ref name=Kaufmann_et_al_2013/> The jet may be the source for the gamma-ray emission in the TeV range.<ref name=Zacharias_et_al_2016/>

==References== <references>

<ref name=SIMBAD>{{cite simbad | title=QSO B1514-24 | access-date=2022-01-24}}.</ref>

<ref name="Fan_2000">{{cite journal | last1=Fan |first1=J. H. | last2=Lin | first2=R. G. | title=Optical Variability and Periodicity Analysis for Blazars. I. Light Curves for Radio-selected BL Lacertae Objects | journal=The Astrophysical Journal | date=July 2000 | volume=537 | issue=1 | pages=101–122 | doi=10.1086/308996 | bibcode=2000ApJ...537..101F |s2cid=121252846 | url=https://iopscience.iop.org/article/10.1086/308996/pdf | access-date=19 September 2022| url-access=subscription }}</ref>

<ref name="Carini_1991">{{cite journal | last1=Carini | first1=M. T. | last2=Miller | first2=H. R. | last3=Noble | first3=J. C. | last4=Sadun | first4=A. C. | title=The Timescales of the Optical Variability of Blazars. II. AP Librae | journal=Astronomical Journal | date=April 1991 | volume=101 | issue=4 | pages=1196–1201 |doi=10.1086/115756 | bibcode=1991AJ....101.1196C | url=https://articles.adsabs.harvard.edu/pdf/1991AJ....101.1196C | access-date=19 September 2022| doi-access=free }}</ref>

<ref name=Ducati2002>{{citation | title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system. | last=Ducati | first=J. R. | work=CDS/ADC Collection of Electronic Catalogues | number=2237 | date=2002 | volume=2237 | postscript=. | bibcode=2002yCat.2237....0D }}</ref>

<ref name=Hunstead1971>{{citation | title=Further Data on the Optical Variable PKS 1514-24 | last=Hunstead | first=R. W. | journal=Nature | postscript=. | volume=233 | issue=5319 | pages=401–402 | date=October 1971 | doi=10.1038/233401a0 | pmid=16063399 | bibcode=1971Natur.233..401H | s2cid=4282407 }}</ref>

<ref name=Andrews_et_al_1974>{{citation | title=Photometry of AP Lib and PKS 0521-36 | display-authors=1 | last1=Andrews | first1=P. J. | last2=Glass | first2=I. S. | last3=Hawarden | first3=T. G. | journal=Monthly Notices of the Royal Astronomical Society | volume=168 | pages=7P–11P | date=July 1974 | postscript=. | doi=10.1093/mnras/168.1.7P | bibcode=1974MNRAS.168P...7A | doi-access=free }}</ref>

<ref name=Bond1971>{{citation | title=The Optically Variable Radio Source PKS 1514-24 = AP Librae | last=Bond | first=Howard E. | postscript=. | journal=Astrophysical Journal | volume=167 | page=L79 | date=July 1971 | doi=10.1086/180764 | bibcode=1971ApJ...167L..79B }}</ref>

<ref name=Roychowdhury_et_al_2022>{{citation | title=Circumnuclear Dust in AP Librae and the Source of Its VHE Emission | display-authors=1 | last1=Roychowdhury | first1=Agniva | last2=Meyer | first2=Eileen T. | last3=Georganopoulos | first3=Markos | last4=Breiding | first4=Peter | last5=Petropoulou | first5=Maria | journal=The Astrophysical Journal | postscript=. | volume=924 | issue=2 | id=57 | pages=19 | date=January 2022 | doi=10.3847/1538-4357/ac34f1 | arxiv=2110.12016 | bibcode=2022ApJ...924...57R | s2cid=239769140 | doi-access=free }}</ref>

<ref name=Visvanathan_Griersmith_1977>{{citation | title=The extended source in AP Librae. | last1=Visvanathan | first1=N. | last2=Griersmith | first2=D. | journal=Astrophysical Journal | postscript=. | volume=215 | pages=759–764 | date=August 1977 | doi=10.1086/155410 | bibcode=1977ApJ...215..759V }}</ref>

<ref name=Peterson_et_al_1976>{{citation | title=The BL Lacertae object AP Librae in 1975 | last1=Peterson | first1=B. A. | last2=Rodgers | first2=A. W. | last3=Wampler | first3=E. J. | last4=Disney | first4=M. J. | display-authors=1 | journal=Astrophysical Journal | volume=207 | pages=L17–L19 | date=July 1976 | postscript=. | doi=10.1086/182168 | bibcode=1976ApJ...207L..17P | doi-access=free }}</ref>

<ref name=Fortin_et_al_2010>{{citation | title=Gamma-ray emission from AP Librae (PKS1514-241) | last1=Fortin | first1=P. | last2=Fegan | first2=S. | last3=Horan | first3=D. | last4=Sanchez | first4=D. | author5=Fermi LAT Collaboration | last6=Gielbels | first6=B. | last7=Becherini | first7=Y. | last8=Dubus | first8=G. | last9=de Naurois | first9=M. | last10=Punch | first10=M. | last11=Raue | first11=M. | author12=H. E. S. S. Collaboration | display-authors=1 | display-editors=1 | postscript=. | work=Proceedings of the 25th [[Texas Symposium on Relativistic Astrophysics]]. December 6-10, 2010. Heidelberg, Germany | editor1-first=Frank M. | editor1-last=Rieger | editor2-first=Christopher | editor2-last=van Eldik | editor3-first=Werner | editor3-last=Hofmann | date=2010 | page=199 | doi=10.22323/1.123.0199 | bibcode=2010tsra.confE.199F | doi-access=free | hdl=11858/00-001M-0000-0012-5C76-4 | hdl-access=free }}</ref>

<ref name=Kaufmann_et_al_2013>{{citation | title=Discovery of an Extended X-Ray Jet in AP Librae | display-authors=1 | last1=Kaufmann | first1=S. | last2=Wagner | first2=S. J. | last3=Tibolla | first3=O. | journal=The Astrophysical Journal | postscript=. | volume=776 | issue=2 | id=68 | pages=7 | date=October 2013 | doi=10.1088/0004-637X/776/2/68 | arxiv=1309.6893 | bibcode=2013ApJ...776...68K | s2cid=118538869 }}</ref>

<ref name=Cassaro_et_al_1999>{{citation | title=Extended radio emission in BL Lac objects. I. The images | last1=Cassaro | first1=P. | last2=Stanghellini | first2=C. | last3=Bondi | first3=M. | last4=Dallacasa | first4=D. | last5=della Ceca | first5=R. | last6=Zappalà | first6=R. A. | display-authors=1 | journal=Astronomy and Astrophysics Supplement | volume=139 | pages=601–616 | postscript=. | date=November 1999 | issue=3 | doi=10.1051/aas:1999511 | arxiv=astro-ph/9910209 | bibcode=1999A&AS..139..601C | s2cid=17687679 }}</ref>

<ref name=Sanchez_et_al_2015>{{citation | title=From radio to TeV: the surprising spectral energy distribution of AP Librae | last1=Sanchez | first1=D. A. | last2=Giebels | first2=B. | last3=Fortin | first3=P. | last4=Horan | first4=D. | last5=Szostek | first5=A. | last6=Fegan | first6=S. | last7=Baczko | first7=A. -K. | last8=Finke | first8=J. | last9=Kadler | first9=M. L. | last10=Kovalev | first10=Y. Y. | last11=Lister | first11=M. L. | last12=Pushkarev | first12=A. B. | last13=Savolainen | first13=T. | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=454 | issue=3 | pages=3229–3239 | postscript=. | date=December 2015 | doi=10.1093/mnras/stv2151 | doi-access=free | arxiv=1506.00965 | bibcode=2015MNRAS.454.3229S }}</ref>

<ref name=Zacharias_et_al_2016>{{citation | title=AP Librae: The Extended Jet as the Source of VHE Emission? | last1=Zacharias | first1=Michael | last2=Wagner | first2=Stefan | journal=Galaxies | postscript=. | volume=4 | issue=4 | page=63 | date=November 2016 | doi=10.3390/galaxies4040063 | bibcode=2016Galax...4...63Z | doi-access=free }}</ref>

<ref name=Skrutskie_et_al_2006>{{citation | display-authors=1 | last1=Skrutskie | first1=Michael F. | last2=Cutri | first2=Roc M. | last3=Stiening | first3=Rae | last4=Weinberg | first4=Martin D. | last5=Schneider | first5=Stephen E. | last6=Carpenter | first6=John M. | last7=Beichman | first7=Charles A. | last8=Capps | first8=Richard W. | last9=Chester | first9=Thomas | last10=Elias | first10=Jonathan H. | last11=Huchra | first11=John P. | last12=Liebert | first12=James W. | last13=Lonsdale | first13=Carol J. | last14=Monet | first14=David G. | last15=Price | first15=Stephan | last16=Seitzer | first16=Patrick | last17=Jarrett | first17=Thomas H. | last18=Kirkpatrick | first18=J. Davy | last19=Gizis | first19=John E. | last20=Howard | first20=Elizabeth V. | last21=Evans | first21=Tracey E. | last22=Fowler | first22=John W. | last23=Fullmer | first23=Linda | last24=Hurt | first24=Robert L. | last25=Light | first25=Robert M. | last26=Kopan | first26=Eugene L. | last27=Marsh | first27=Kenneth A. | last28=McCallon | first28=Howard L. | last29=Tam | first29=Robert | last30=Van Dyk | first30=Schuyler D. | last31=Wheelock | first31=Sherry L. | title=The Two Micron All Sky Survey (2MASS) | journal=The Astronomical Journal | postscript=. | date=February 1, 2006 | volume=131 | issue=2 | pages=1163–1183 | bibcode=2006AJ....131.1163S | doi=10.1086/498708 | s2cid=18913331 | issn=0004-6256 | doi-access=free }}</ref>

</references>

==Further reading== {{Div col|small=yes}} *{{citation | title=What is the origin of the VHE emission in AP Librae? | display-authors=1 | last1=Meyer | first1=E. | last2=Roychowdhury | first2=A. | last3=Georganopoulos | first3=M. | journal=Bulletin of the American Astronomical Society | volume=53 | issue=1 | id=2021n1i238p05 | postscript=. | date=January 2021 | bibcode=2021AAS...23723805M }} *{{citation | title=Constraints on a Proton Synchrotron Origin of VHE Gamma Rays from the Extended Jet of AP Librae | last1=Pratim Basumallick | first1=Partha | last2=Gupta | first2=Nayantara | journal=The Astrophysical Journal | postscript=. | volume=844 | issue=1 | id=58 | pages=9 | date=July 2017 | doi=10.3847/1538-4357/aa7a12 | arxiv=1706.04895 | bibcode=2017ApJ...844...58P | s2cid=119480675 | doi-access=free }} *{{citation | last1=Zacharias | first1=Michael | last2=Wagner | first2=Stefan J. | chapter=The extended jet in AP Librae as the source of the VHE γ-ray emission | title=6th International Symposium on High Energy Gamma-Ray Astronomy | series=AIP Conference Proceedings | postscript=. | volume=1792 | date=January 2017 | issue=1 | page=050014 | doi=10.1063/1.4968960 | arxiv=1611.02103 | bibcode=2017AIPC.1792e0014Z | s2cid=9135990 }} *{{citation | title=The TeV emission of Ap Librae: a hadronic interpretation and prospects for CTA | display-authors=1 | last1=Petropoulou | first1=M. | last2=Vasilopoulos | first2=G. | last3=Giannios | first3=D. | journal=Monthly Notices of the Royal Astronomical Society | volume=464 | issue=2 | pages=2213–2222 | postscript=. | date=January 2017 | doi=10.1093/mnras/stw2453 | doi-access=free | arxiv=1608.07300 | bibcode=2017MNRAS.464.2213P }} *{{citation | title=Fermi LAT detection of a GeV gamma-ray flare from the BL Lac object AP Librae | last=Ciprini | first=Stefano | journal=The Astronomer's Telegram | number=9442 | date=August 2016 | volume=9442 | page=1 | bibcode=2016ATel.9442....1C | postscript=. }} *{{citation | title=The extended jet of AP Librae: Origin of the very high-energy γ-ray emission? | last1=Zacharias | first1=Michael | last2=Wagner | first2=Stefan J. | journal=Astronomy & Astrophysics | volume=588 | id=A110 | pages=13 | postscript=. | date=April 2016 | doi=10.1051/0004-6361/201526698 | arxiv=1602.03430 | bibcode=2016A&A...588A.110Z | s2cid=119279663 }} *{{citation | title=Linking radio and gamma-ray emission in Ap Librae | display-authors=1 | last1=Hervet | first1=O. | last2=Boisson | first2=C. | last3=Sol | first3=H. | journal=Astronomy & Astrophysics | volume=578 | id=A69 | pages=11 | postscript=. | date=June 2015 | doi=10.1051/0004-6361/201425330 | arxiv=1503.01377 | bibcode=2015A&A...578A..69H | s2cid=53522733 }} *{{citation | title=The high-energy γ-ray emission of AP Librae | author=H. E. S. S. Collaboration | author-link=High Energy Stereoscopic System | display-authors=etal | journal=Astronomy & Astrophysics | volume=573 | id=31 | pages= 7 | postscript=. | date=January 2015 | doi=10.1051/0004-6361/201321436 | arxiv=1410.5897 | bibcode=2015A&A...573A..31H | s2cid=207807491 }} *{{citation | title=The high-energy γ-ray emission of AP Librae | author=H.E.S.S. Collaboration | display-authors=etal | journal=Astronomy & Astrophysics | postscript=. | volume=573 | date=January 2015 | id=A31 | pages=7 | doi=10.1051/0004-6361/201321436 | arxiv=1410.5897 | bibcode=2015A&A...573A..31H | s2cid=207807491 }} *{{citation | title=The challenging SED of AP Librae | display-authors=1 | last1=Sanchez | first1=David | last2=Giebels | first2=Berrie | last3=Fortin | first3=Pascal | work=The Spectral Energy Distribution of Galaxies, Proceedings of the International Astronomical Union, IAU Symposium | volume=284 | pages=411–413 | date=August 2012 | postscript=. | doi=10.1017/S1743921312009532 | bibcode=2012IAUS..284..411S | doi-access=free }} *{{citation | title=The Optical Variability of PKS 1510-089, PKS 1622-297 and AP Librae | display-authors=1 | last1=Gudkova | first1=Diana | last2=Miller | first2=Richard | last3=Eggen | first3=Joe | last4=Maune | first4=Jeremy | last5=Marshall | first5=Kevin | work=American Physical Society, 76th Annual Meeting of the Southeastern Section of APS, November 11-13, 2009 | id=PB.002 | date=November 2009 | volume=76 | bibcode=2009APS..SES.PB002G | postscript=. }} *{{citation | title=Photometric analysis and decomposition of AP Librae (PKS 1514-24). | display-authors=1 | last1=Baxter | first1=D. A. | last2=Disney | first2=M. J. | last3=Phillipps | first3=S. | journal=Monthly Notices of the Royal Astronomical Society | volume=228 | pages=313–327 | date=September 1987 | issue=2 | postscript=. | doi=10.1093/mnras/228.2.313 | bibcode=1987MNRAS.228..313B | doi-access=free }} *{{citation | title=The properties of AP Lib from UBV photoelectric photometry | display-authors=1 | last1=Westerlund | first1=B. E. | last2=Wlerick | first2=G. | last3=Garnier | first3=R. | journal=Astronomy and Astrophysics | postscript=. | volume=105 | pages=284–292 | date=January 1982 | bibcode=1982A&A...105..284W }} *{{citation | title=Polarization of 3C 371 and AP Librae at 2.2μm | last1=Capps | first1=R. W. | last2=Knacke | first2=R. F. | journal=Astrophysical Letters | volume=19 | pages=113 | postscript=. | date=1978 | bibcode=1978ApL....19..113C }} *{{citation | title=Emission lines in AP Librae in 1976 | last1=Rodgers | first1=A. W. | last2=Peterson | first2=B. A. | journal=Astrophysical Journal | postscript=. | volume=212 | pages=L9–L12 | date=February 1977 | doi=10.1086/182363 | bibcode=1977ApJ...212L...9R | doi-access=free }} *{{citation | title=The Redshift and Composite Nature of AP Librae (pks 1514-24) | display-authors=1 | last1=Disney | first1=M. J. | last2=Peterson | first2=B. A. | last3=Rodgers | first3=A. W. | journal=Astrophysical Journal | postscript=. | volume=194 | page=L79 | date=December 1974 | doi=10.1086/181673 | bibcode=1974ApJ...194L..79D }} *{{citation | title=Rapid optical variability of the extragalactic radio source PKS 1514-24 | last1=Miller | first1=H. R. | last2=Clonts | first2=S. L. | last3=Folsom | first3=G. H. | journal=Astronomical Journal | volume=79 | page=1352 | date=December 1974 | doi=10.1086/111685 | bibcode=1974AJ.....79.1352M | doi-access=free }} {{Div col end}}

[[Category:BL Lacertae objects]] [[Category:Libra (constellation)]] [[Category:Elliptical galaxies]] [[Category:Objects with variable star designations|Librae, AP]]