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]
 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)[1] | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 17m 55.38s[2] |
| Declination | −08° 21′ 04.6″[2] |
| Apparent magnitude (V) | 12.7[3] |
| Characteristics | |
| Apparent magnitude (B) | 13.70[2] |
| Apparent magnitude (R) | 13.60[2] |
| Apparent magnitude (J) | 12.87[2] |
| Apparent magnitude (H) | 12.75[2] |
| Apparent magnitude (K) | 12.51[2] |
| Variable type | DQ[4] |
| Orbit | |
| Period (P) | 4.85 hr[5] |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), Bright Star Catalogue (5th rev. ed.) | |
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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