FO Aquarii

FO Aquarii
	; The visual band light curve of FO Aquarii. The main plot shows the dimming which occurred in 2016, and the inset plot shows the short-term variation that occurs during an orbital period. Adapted from Littlefield et al. (2016)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	22h 17m 55.38s
Declination	−08° 21′ 04.6″
Apparent magnitude (V)	12.7
Characteristics
Apparent magnitude (B)	13.70
Apparent magnitude (R)	13.60
Apparent magnitude (J)	12.87
Apparent magnitude (H)	12.75
Apparent magnitude (K)	12.51
Variable type	DQ
Orbit
Period (P)	4.85 hr
Other designations
	2E 4588, 1RXS J221753.9-082115, CS 22886-0021, H 2215-086
Database references
SIMBAD	data
Data sources:
Hipparcos Catalogue,; CCDM (2002),; Bright Star Catalogue (5th rev. ed.)

FO Aquarii is an intermediate polar^[4] star system in the constellation Aquarius. The white dwarf and companion star orbit each other with a period of approximately 4.85 hours.^[5] The system is famous for a very strong optical pulsation which occurs every 20.9 minutes, corresponding with the rotational period of the accreting white dwarf.^[6] Prior to 2016, the system's long-term optical brightness varied between apparent magnitude 12.7 and 14.2,^[7] but in early 2016, it faded to magnitude 15.8 and thereafter began a slow recovery to its normal brightness, behavior which is indicative of a temporary dropoff in the mass-transfer rate between the two stars.^[8]

References[edit]

^ Littlefield, Colin; Garnavich, Peter; Kennedy, Mark R.; Aadland, Erin; Terndrup, Donald M.; Calhoun, Grace V.; Callanan, Paul; Abe, Lyu; Bendjoya, Philippe; Rivet, Jean-Pierre; Vernet, David; Devogèle, Maxime; Shappee, Benjamin; Holoien, Thomas; Heras, Teófilo Arranz; Bonnardeau, Michel; Cook, Michael; Coulter, Daniel; Debackère, André; Dvorak, Shawn; Foster, James R.; Goff, William; Hambsch, Franz-Josef; Harris, Barbara; Myers, Gordon; Nelson, Peter; Popov, Velimir; Solomon, Rob; Stein, William L.; Stone, Geoff; Vietje, Brad (December 2016). "Return of the King: Time-Series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State". The Astrophysical Journal. 833 (1): 93. arXiv:1609.01026. Bibcode:2016ApJ...833...93L. doi:10.3847/1538-4357/833/1/93. S2CID 54662277.
^ ^a ^b ^c ^d ^e ^f ^g Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
^ Samus’, N. N.; Goranskii, V. P.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L. (2003). "An electronic version of the second volume of the General Catalogue of Variable Stars with improved coordinates". Astronomy Letters. 29 (7): 468–479. Bibcode:2003AstL...29..468S. doi:10.1134/1.1589864. S2CID 16299532.
^ ^a ^b Pekön, Y.; Balman, Ş. (2012). "Orbital-phase-resolved Spectroscopy of the Intermediate Polar FO Aqr Using XMM-Newton Observatory Data". The Astronomical Journal. 144 (2): 53. arXiv:1206.2215. Bibcode:2012AJ....144...53P. doi:10.1088/0004-6256/144/2/53. S2CID 119215497.
^ ^a ^b Osborne, J.; Mukai, K. (1989). "New Orbital and Spin Ephemerides of the Intermediate Polar Fo-Aquarii = H:2215-086". Monthly Notices of the Royal Astronomical Society. 238 (3): 1233–1246. Bibcode:1989MNRAS.238.1233O. doi:10.1093/mnras/238.4.1233.
^ Patterson, J.; Steiner, J. E. (1983-01-01). "H2215-086 -King of the DQ Herculis stars". The Astrophysical Journal. 264: L61. Bibcode:1983ApJ...264L..61P. doi:10.1086/183944. ISSN 0004-637X.
^ VSX; Otero, S. A. (24 May 2011). "FO Aquarii". AAVSO Website. American Association of Variable Star Observers. Retrieved 10 October 2014.
^ Littlefield, Colin; Garnavich, Peter; Kennedy, Mark R.; Aadland, Erin; Terndrup, Donald M.; Calhoun, Grace V.; Callanan, Paul; Abe, Lyu; Bendjoya, Philippe (2016-01-01). "Return of the King: Time-series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State". The Astrophysical Journal. 833 (1): 93. arXiv:1609.01026. Bibcode:2016ApJ...833...93L. doi:10.3847/1538-4357/833/1/93. ISSN 0004-637X. S2CID 54662277.

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[Littlefield-1] Littlefield, Colin; Garnavich, Peter; Kennedy, Mark R.; Aadland, Erin; Terndrup, Donald M.; Calhoun, Grace V.; Callanan, Paul; Abe, Lyu; Bendjoya, Philippe; Rivet, Jean-Pierre; Vernet, David; Devogèle, Maxime; Shappee, Benjamin; Holoien, Thomas; Heras, Teófilo Arranz; Bonnardeau, Michel; Cook, Michael; Coulter, Daniel; Debackère, André; Dvorak, Shawn; Foster, James R.; Goff, William; Hambsch, Franz-Josef; Harris, Barbara; Myers, Gordon; Nelson, Peter; Popov, Velimir; Solomon, Rob; Stein, William L.; Stone, Geoff; Vietje, Brad (December 2016). "Return of the King: Time-Series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State". The Astrophysical Journal. 833 (1): 93. arXiv:1609.01026. Bibcode:2016ApJ...833...93L. doi:10.3847/1538-4357/833/1/93. S2CID 54662277.

[2MASS-2] ^ ^a ^b ^c ^d ^e ^f ^g Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.

[GCVS-3] Samus’, N. N.; Goranskii, V. P.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L. (2003). "An electronic version of the second volume of the General Catalogue of Variable Stars with improved coordinates". Astronomy Letters. 29 (7): 468–479. Bibcode:2003AstL...29..468S. doi:10.1134/1.1589864. S2CID 16299532.

[Pekön2012-4] Pekön, Y.; Balman, Ş. (2012). "Orbital-phase-resolved Spectroscopy of the Intermediate Polar FO Aqr Using XMM-Newton Observatory Data". The Astronomical Journal. 144 (2): 53. arXiv:1206.2215. Bibcode:2012AJ....144...53P. doi:10.1088/0004-6256/144/2/53. S2CID 119215497.

[Osborne_1989-5] Osborne, J.; Mukai, K. (1989). "New Orbital and Spin Ephemerides of the Intermediate Polar Fo-Aquarii = H:2215-086". Monthly Notices of the Royal Astronomical Society. 238 (3): 1233–1246. Bibcode:1989MNRAS.238.1233O. doi:10.1093/mnras/238.4.1233.

[6] Patterson, J.; Steiner, J. E. (1983-01-01). "H2215-086 -King of the DQ Herculis stars". The Astrophysical Journal. 264: L61. Bibcode:1983ApJ...264L..61P. doi:10.1086/183944. ISSN 0004-637X.

[AAVSO-7] VSX; Otero, S. A. (24 May 2011). "FO Aquarii". AAVSO Website. American Association of Variable Star Observers. Retrieved 10 October 2014.

[8] Littlefield, Colin; Garnavich, Peter; Kennedy, Mark R.; Aadland, Erin; Terndrup, Donald M.; Calhoun, Grace V.; Callanan, Paul; Abe, Lyu; Bendjoya, Philippe (2016-01-01). "Return of the King: Time-series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State". The Astrophysical Journal. 833 (1): 93. arXiv:1609.01026. Bibcode:2016ApJ...833...93L. doi:10.3847/1538-4357/833/1/93. ISSN 0004-637X. S2CID 54662277.

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