CI Aquilae
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Double star CI Aquilae |
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| AladinLite | |||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Eagle | ||||
| Right ascension | 18 h 52 m 3.55 s | ||||
| declination | -01 ° 28 ′ 39.2 ″ | ||||
| Apparent brightness | 16.3 mag | ||||
| Typing | |||||
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rel. Brightness (G-band) |
(15,762 ± 0.006) mag | ||||
| rel. Brightness (J-band) |
(13.67 ± 0.043) mag | ||||
| Spectral class | cont | ||||
| Variable star type | NR + E | ||||
| Astrometry | |||||
| parallax | (0.326 ± 0.051) mas | ||||
| distance | 5053 Lj 1550 pc |
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| Proper movement | |||||
| Rec. Share: | (2.8 ± 5.02) mas / a | ||||
| Dec. portion: | (7.8 ± 5.0) mas / a | ||||
| Physical Properties | |||||
| Dimensions | 1.2 / 1.5 M ☉ | ||||
| radius | 0.0072 / 1.69 R ☉ | ||||
| Effective temperature | 6,300 K | ||||
| Rotation time | 14.84066 h | ||||
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Other names and catalog entries |
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CI Aquilae also CI Aql is a recurrent or recurring nova of type NR. The system consists of a white dwarf with about 1.2 M ☉ , which isorbitedby a companion star with 1.5 M ☉ . The first known outbreak was discovered in 1925 by K. Reinmuth on 16 "photo plates that were taken in June 1917 with the Bruce telescope of the Heidelberg-Königstuhl State Observatory.
Together with U Scorpii, V394 Coronae Austrinae, RS Ophiuchi , T Coronae Borealis , V745 Scorpio, V3890 Sagittarius, T Pyxidis , and IM Normae, CI Aquilae forms a small but heterogeneous group of 9 to 10 objects in the Milky Way that are undergoing nova-like eruptions. These outbreaks have a smaller amplitude and release less energy than the classic novae. They occur at intervals of about 10 to 100 years. It is widely believed that the white dwarfs in these binary star systems are close to the Chandrasekhar boundary . The mass transfer rate from the companion star to the white dwarf is high and is in the order of magnitude of approx. 10 -7 M ☉ per year, corresponding to 6.3 trillion tons per second . These features strongly suggest that recurring white dwarf novae, whose entire mass is united in the oxygen-carbon core, are immediate precursors of Type Ia supernovae.
Recurrent novas are divided into three further subclasses, depending on their period of rotation.
- The subclass T Pyxidis with a dwarf companion .
- The subclass U Scorpii with a slightly developed main sequence star or subgiant .
- The RS Ophiuchi subclass with a red giant star .
CI Aql has an orbital period of 0.618 days and thus belongs to the subclass U Scorpii.
BE Schaefer, of the University of Texas at Austin, reported in 2001 that an eruption of the Nova CI Aql was found on 12 archive photos of the Harvard College Observatory from 1941. He deduces from this that it could be a recurring nova with a span of 20 years where the outbreaks in 1960 and 1980 were overlooked.
Individual evidence
- ↑ a b c d e NOVA Aql 1917. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed April 4, 2019 .
- ↑ a b c d CI Aql. In: VSX. AAVSO , accessed April 4, 2019 .
- ↑ a b c d e C. Lederle, S. Kimeswenger: Modeling the Recurrent Nova CI Aql in Quiescence . In: Institute for Astrophysics at the Leopold-Franzens-University Innsbruck . September 27, 2002. doi : 10.1051 / 0004-6361: 20021539 .
- ↑ Locations and brightnesses of 100 variables. In: Reinmuth, K. Astronomische Nachrichten, volume 225, Issue 23, p.385, accessed on April 8, 2019 .
- ^ Webbink, Ronald F .; Livio, Mario; Truran, James W .; Orio, Marina: The nature of the recurrent novae . In: The Astrophysical Journal . March 15, 1987. doi : 10.1086 / 165095 .
- ↑ Hachisu, Izumi, et al .: Prediction of the Supersoft X-Ray Phase, Helium Enrichment, and Turnoff Time in the 2000 Outburst of the Recurrent Nova Ci Aquilae . In: The Astrophysical Journal, Volume 553, Issue 2, pp. L161-L164. . June 2001. arxiv : astro-ph / 0104461 . bibcode : 2001ApJ ... 553L.161H . doi : 10.1086 / 320693 .
- ^ CI Aquilae. In: Schaefer, BE IAU Circ., No. 7750, # 2 (2001). Edited by Green, DWE, accessed April 8, 2019 .