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W Aquilae

W Aquilae showing the close companion Credit: Hubble Legacy Archive
Observation data Epoch J2000      Equinox J2000
Constellation	Aquila
Right ascension	19 15 23.357
Declination	−07° 02′ 50.33″
Apparent magnitude (V)	A: 7.0 - 14.6 B:14.8
Characteristics
A
Evolutionary stage	asymptotic giant branch
Spectral type	S6/6e (S3,9e - S6,9e)
B−V color index	+2.58
Variable type	Mira
B
Evolutionary stage	main sequence
Spectral type	F8/9
Astrometry
Radial velocity (Rv)	−18.0 km/s
Proper motion (μ)	RA: 15.713 mas/yr Dec.: 0.103 mas/yr
Parallax (π)	2.6735 ± 0.1392 mas
Distance	1,220 ± 60 ly (370 ± 20 pc)
Absolute magnitude (MV)	A: −0.7 to +6.9 B: +7.1
Details
A
Mass	1.04 - 3 M☉
Radius	444 R☉
Luminosity	7,500 L☉
Temperature	2,800 K
B
Mass	1.04 - 1.09 M☉
Temperature	5,900 - 6,170 K
Other designations
W Aql, IRAS 19126-0708, TYC 5142-2895-1, 2MASS J19152335-0702503, AAVSO 1910-07, Gaia DR2 420492505899016640
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.

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 solar masses per year. Its effective temperature is about 2,800 K and its radius is equivalent to 440 solar radii. It is also a very luminous star, 7,500 times more than the sun.

Variability

In 1893, Leo Anton Carl de Ball announced that the then unnamed star was a variable star, whose brightness varied by at least one magnitude. It was listed with its variable star designation, W Aquilae, in Annie Jump Cannon's 1907 Second Catalogue of Variable Stars.

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.

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.

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.

Notes

1. ^ Radius calculated with angular diameter and distance in Table 1

References

1. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. ^ Samus, N. N.; Durlevich, O. V.; 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. ^ Mayer, A.; Jorissen, A.; Kerschbaum, F.; Ottensamer, R.; Nowotny, W.; Cox, N. L. J.; Aringer, B.; Blommaert, J. A. D. L.; Decin, L.; Van Eck, S.; Gail, H.-P.; Groenewegen, M. A. T.; Kornfeld, K.; Mecina, M.; Posch, Thomas; Vandenbussche, B.; Waelkens, C. (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. arXiv:1211.3595. Bibcode:2013A&A...549A..69M. doi:10.1051/0004-6361/201219259. S2CID 55538633.
4. ^ 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. arXiv:1501.00863. Bibcode:2015A&A...574A..23D. doi:10.1051/0004-6361/201423672. S2CID 15587164.
5. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 0333750888.
6. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
7. ^ Wallstrom, S. H. J.; Danilovich, T.; Muller, H. S. P.; Gottlieb, C. A.; Maes, S.; Van de Sande, M.; Decin, L.; Richards, A. M. S.; Baudry, A.; Bolte, J.; Ceulemans, T.; De Ceuster, F.; de Koter, A.; Mellah, I. El; Esseldeurs, M. (December 6, 2023). "ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA". Astronomy & Astrophysics. 681: A50. arXiv:2312.03467. doi:10.1051/0004-6361/202347632. ISSN 0004-6361.
8. ^ 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. arXiv:1806.01622. doi:10.1051/0004-6361/201832724. S2CID 67754573.
9. Danilovich, T.; et al. (2021). "ATOMIUM: Halide molecules around the S-type AGB star W Aquilae". Astronomy & Astrophysics. 655: A80. arXiv:2109.04747. Bibcode:2021A&A...655A..80D. doi:10.1051/0004-6361/202141757. S2CID 237485542.
10. 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. arXiv:1408.1825. Bibcode:2014A&A...569A..76D. doi:10.1051/0004-6361/201322807. S2CID 55615864.
11. de Ball, Leo (August 1893). "Über einen neuen veränderlichen Stern in Aquila". Astronomische Nachrichten. 133: 215. Bibcode:1893AN....133..215D. Retrieved 23 November 2024.
12. Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 21 November 2024.
13. "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
14. Ramstedt, Sofia; Vlemmings, Wouter; Mohamed, Shazrene; Choi, Yoon Kyung; Olofsson, Hans (July 2012). "TWINKLING STARS the disappearing SiO masers of W Aql". Proceedings of the International Astronomical Union. 287: 260–261. Bibcode:2012IAUS..287..260R. doi:10.1017/S1743921312007107. S2CID 123608578.
15. Vlemmings, W.; Ramstedt, S.; Maercker, M.; Davidsson, B. (2015). "The serendipitous discovery of a possible new solar system object with ALMA". arXiv:1512.02650 .

v t e Constellation of Aquila
Aquila in Chinese astronomy List of stars in Aquila
Stars	Bayer α (Altair) β (Alshain) γ (Tarazed) δ ε ζ (Okab) η θ (Tseen Foo) ι κ λ μ ν ξ (Libertas) ο π σ τ υ φ χ ψ ω ω A b c d e f g h i k l Flamsteed 4 5 7 8 10 11 18 19 20 21 22 23 24 42 45 46 51 56 57 58 62 64 66 68 69 70 14 Sge 62 Ser 64 Sgr Variable R U V W TT FF QS V368 V450 V500 V603 V604 V605 V606 V923 V1286 V1291 V1298 V1302 V1315 V1333 V1339 V1427 V1428 V1429 V1472 V1487 V1494 V1654 V1672 V1691 V1703 (Phoenicia) V1828 V1936 HR 7099 7143 7288 7300 7307 7396 7456 7569 7598 7599 7693 7717 7803 HD 179079 183263 187734 192699 (Chechia) Other CoRoT-2 CoRoT-3 CoRoT-8 Gaia BH3 HAT-P-41 PSR J1856+0245 PSR J1903+0327 PSR B1913+16 (Hulse–Taylor) PSR J1951+1123 SGR 1900+14 SS 433 W43A W49-2 WASP-80 (Petra) WD J1953−1019 ZTF J1901+1458
Exoplanets CoRoT-2b CoRoT-3b CoRoT-8b CoRoT-10b HD 179079 b HD 183263 b c HD 192263 b HD 192699 b ξ Aquilae b
Star clusters NGC 6709 NGC 6738 NGC 6755 NGC 6756 NGC 6760
Nebulae	NGC 6741 6751 6778 6781 6790 Other Abell 48 Abell 70 E Nebula Hen 2-428 HESS J1857+026 Kesteven 75 Smith's Cloud W43 W49 W49B W50
Galaxies	NGC 6814 Other IC 1327
Category

• S-type stars
• Mira variables
• Aquila (constellation)
• Objects with variable star designations
• 2MASS objects
• IRAS catalogue objects
• Binary stars
• F-type main-sequence stars
• Emission-line stars