Astronomy:W Aquilae
 W Aquilae showing the close companion Credit: Hubble Legacy Archive | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 15m 23.357s[1] |
| Declination | −07° 02′ 50.33″[1] |
| Apparent magnitude (V) | A: 7.0 - 14.6[2] B:14.8 [3] |
| Characteristics | |
| A | |
| Evolutionary stage | asymptotic giant branch[4] |
| Spectral type | S6/6e[4] (S3,9e - S6,9e[2]) |
| B−V color index | +2.58[5] |
| Variable type | Mira[2] |
| B | |
| Evolutionary stage | main sequence[4] |
| Spectral type | F8/9[4] |
| Astrometry | |
| Radial velocity (Rv) | −18.0[6] km/s |
| Proper motion (μ) | RA: 15.713[1] mas/yr Dec.: 0.103[1] mas/yr |
| Parallax (π) | 2.6735 ± 0.1392[1] mas |
| Distance | 1,220 ± 60 ly (370 ± 20 pc) |
| Absolute magnitude (MV) | A: −0.7 to +6.9[3] B: +7.1[3] |
| Details | |
| A | |
| Mass | 1.04 - 3[4] M☉ |
| Radius | 400[7] - 480[8] R☉ |
| Luminosity | 7,500[9] L☉ |
| Temperature | 2,300[9] - 3,000[7] K |
| B | |
| Mass | 1.04 - 1.09[4] M☉ |
| Temperature | 5,900 - 6,170[4] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
W Aquilae (W Aql) is a variable star in the constellation of Aquila. It is a type of evolved star known as an S-type star. Due to its relatively close distance of 1,200 light-years (370 pc) and equatorial location, it is easy to observe and heavily studied.[10]
Description
W Aquilae is an S-type star with a spectral type of S3,9e to S6,9e, a red giant similar to M-type stars, but in which the dominant spectrum oxides are formed by metals of the fifth period of the periodic table. W Aquilae is also rich in the element technetium. Another feature of this class of stars is the stellar mass loss, in the case of W Aquilae is estimated at 4×10−6 solar masses per year.[11] Its effective temperature varies between 2,300 and 3,000 K and its diameter between 400 and 480 solar radii.[7][8] It is also a very luminous star, 7,500 times more than the sun.[9]
Variability
W Aquilae is a variable whose brightness oscillates between magnitude +7.3 and +14.3 over a period of 490.43 days. In Mira variables (which are named after Mira, the prototype), this instability comes from pulsation in the stellar surface, causing changes in color and brightness. W Aquilae, a Mira variable, shows silicon monoxide maser emission.[13]
Companion
A magnitude 14.8 companion has been detected 0.47" SW of W Aquilae. This is fainter than W Aquilae at minimum and corresponds to an absolute magnitude of +7.1. Although that absolute magnitude would correspond to a K4 main sequence star, a spectrum was classified as F5 or F8. The separation between the two stars is 160 AU.[3]
Planet X
A 2014 study of W Aquilae and α Centauri with the ALMA array claimed to have accidentally detected a previously-unknown Solar System object. This received widespread press coverage as a potential discovery of planet X. The paper was withdrawn without being accepted for peer-reviewed publication.[14]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Samus, N. N. et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S 1. Bibcode: 2009yCat....102025S.
- ↑ 3.0 3.1 3.2 3.3 Mayer, A.; Jorissen, A.; Kerschbaum, F.; Ottensamer, R.; Nowotny, W.; Cox, N. L. J.; Aringer, B.; Blommaert, J. A. D. L. et al. (2013). "Large-scale environments of binary AGB stars probed by Herschel. I. Morphology statistics and case studies of R Aquarii and W Aquilae". Astronomy & Astrophysics 549: A69. doi:10.1051/0004-6361/201219259. Bibcode: 2013A&A...549A..69M.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Danilovich, T.; Olofsson, G.; Black, J. H.; Justtanont, K.; Olofsson, H. (2015). "Classifying the secondary component of the binary star W Aquilae". Astronomy & Astrophysics 574: A23. doi:10.1051/0004-6361/201423672. Bibcode: 2015A&A...574A..23D.
- ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27. doi:10.1888/0333750888/2862. ISBN 0333750888. Bibcode: 2000A&A...355L..27H.
- ↑ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode: 1953GCRV..C......0W.
- ↑ 7.0 7.1 7.2 Ramstedt, S.; Mohamed, S.; Vlemmings, W. H. T.; Danilovich, T.; Brunner, M.; De Beck, E.; Humphreys, E. M. L.; Lindqvist, M. et al. (2017). "The circumstellar envelope around the S-type AGB star W Aql". Astronomy & Astrophysics 605: A126. doi:10.1051/0004-6361/201730934. PMID 29142327.
- ↑ 8.0 8.1 Ramstedt, S.; Schöier, F. L.; Olofsson, H. (2009). "Circumstellar molecular line emission from S-type AGB stars: mass-loss rates and SiO abundances". Astronomy and Astrophysics 499 (2): 515. doi:10.1051/0004-6361/200911730. 515-527. Bibcode: 2009A&A...499..515R.
- ↑ 9.0 9.1 9.2 Brunner, M.; Danilovich, T.; Ramstedt, S.; Marti-Vidal, I.; De Beck, E.; Vlemmings, W. H. T.; Lindqvist, M.; Kerschbaum, F. (2018). "Molecular line study of the S-type AGB star W Aquilae". Astronomy & Astrophysics 617: A23. doi:10.1051/0004-6361/201832724.
- ↑ Danilovich, T. et al. (2021). "ATOMIUM: Halide molecules around the S-type AGB star W Aquilae". Astronomy & Astrophysics 655: A80. doi:10.1051/0004-6361/202141757. Bibcode: 2021A&A...655A..80D.
- ↑ Danilovich, T.; Bergman, P.; Justtanont, K.; Lombaert, R.; Maercker, M.; Olofsson, H.; Ramstedt, S.; Royer, P. (2014). "Detailed modelling of the circumstellar molecular line emission of the S-type AGB star W Aquilae". Astronomy & Astrophysics 569: A76. doi:10.1051/0004-6361/201322807. Bibcode: 2014A&A...569A..76D.
- ↑ "Download Data". AAVSO. https://www.aavso.org/data-download.
- ↑ Ramstedt, Sofia; Vlemmings, Wouter; Mohamed, Shazrene; Choi, Yoon Kyung; Olofsson, Hans (July 2012). "TWINKLING STARS The disappearing SiO masers of W Aql". Cosmic Masers - from OH to H0, Proceedings of the International Astronomical Union, IAU Symposium 287: 260–261. doi:10.1017/S1743921312007107. Bibcode: 2012IAUS..287..260R.
- ↑ Vlemmings, W.; Ramstedt, S.; Maercker, M.; Davidsson, B. (2015). "The serendipitous discovery of a possible new solar system object with ALMA". arXiv:1512.02650 [astro-ph.SR].
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