W Aquilae

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W Aquilae
W Aquilae binary.jpg
W Aquilae showing the close companion
Credit: Hubble Legacy Archive
Observation data
Epoch J2000       Equinox J2000
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  mas [1]
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 444 [7] [a]   R☉
Luminosity 7,500 [8]   L☉
Temperature 2,800 [7]   K
B
Mass 1.04 - 1.09 [4]   M☉
Temperature 5,900 - 6,170 [4]   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. [9]

Contents

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. [10] Its effective temperature is about 2,800 K and its radius is equivalent to 440 solar radii. [7] [a] It is also a very luminous star, 7,500 times more than the sun. [8]

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. [11] It was listed with its variable star designation, W Aquilae, in Annie Jump Cannon's 1907 Second Catalogue of Variable Stars. [12]

The visual band light curve of W Aquilae, from AAVSO data WAqlLightCurve.png
The visual band light curve of W Aquilae, from AAVSO data

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. [14]

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. [15]

Notes

  1. 1 2 Radius calculated with angular diameter and distance in Table 1

References

  1. 1 2 3 4 5 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. 1 2 3 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. 1 2 3 4 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. 1 2 3 4 5 6 7 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. 1 2 3 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. 1 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. 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 [astro-ph.SR].
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