18 Aquilae

Triple star system in the constellation Aquila Aquila constellation map.svg center 260 right Red circle.svg 8 18 Aql 736 274 Location of 18 Aquilae (circled) J2000 19 06 58.60289 +11 04 16.4173 5.072 Aquila B8 III −0.08 −0.44 Eclipsing −18.6 −0.89 −32.11 6.43 0.79 A B 205.16 0.23 134.3 0.399 Aa Ab 1.3023 d 27.6 Aa 5.6 4,875 50 Ab 0.38 12.7 y B 3.49 Y Aquilae, 18 Aql, BD+10 3787, FK5 3525, HD 178125, HIP 93867, HR 7248, SAO 104488 18+Aql 18 Aquilae (abbreviated 18 Aql) is a triple star system in the constellation of Aquila. 18 Aquilae is the Flamsteed designation; it also bears the variable star designation Y Aquilae. It has an apparent visual magnitude of 5.07, making it bright enough to be seen with the naked eye. The distance to this system can be estimated from the annual parallax shift of 6.43 mas, yielding a value of around 510 ly pc off on away from Earth. It took decades to determine whether or not 18 Aquilae is a variable star. It was used as a standard star in Benjamin Apthorp Gould's Uranometria Argentina, published in 1879. Gould marked the star with an asterisk, indicating that he thought it is a variable star. Gustav Müller and Paul Kempf noted Gould's opinion in their 1894 work Potsdamer Photometrische Durchmusterung, but stated that their numerous observations did not confirm that the star is variable. That same year, Seth Carlo Chandler reported that 18 Aquilae is a variable star. He stated the star showed an "unmistakable periodicity" and derived a period of 4.986 days - nearly 4 times larger than what the period is now known to be. Chandler gave the star the name Y Aquilae. In 1898, Edward Charles Pickering and Paul S. Yendell announced that their observations of the star "fail to show any evidence of variation". In 1966, Robert Arnold Breinhorst established that Y Aquilae is variable in his PhD thesis. thumb|left|A light curve for Y Aquilae, plotted from TESS data The inner pair of stars in this system form a spectroscopic binary with a combined magnitude of 5.44 and an orbital period of 1.302 days. The primary component is a giant star with a stellar classification of B8 III. Because the orbital plane is inclined near the line of sight, two form an eclipsing binary system. The eclipse of the primary component causes a 0.04 drop in magnitude, while the eclipse of the secondary results in a decrease of 0.03. At an angular separation of 0.310 arcseconds is the magnitude 6.39 tertiary component. This system has a high peculiar velocity of 29.7 ± 3.9 km/s relative to the neighboring stars. References Gould Benjamin Apthorp Uranometria Argentina: Brightness and position of every fixed star, down to the seventh magnitude, within one hundred degrees of the South Pole; with atlas Resultados del Observatorio Nacional Argentino 1879 1 I-387 1879RNAO....1....1G https://articles.adsabs.harvard.edu/pdf/1879RNAO....1D...1G 24 November 2024 Chandler S. C. On a new variable of short period Astronomical Journal November 1894 14 329 135 10.1086/102123 1894AJ.....14..135C https://articles.adsabs.harvard.edu/pdf/1894AJ.....14..135C 24 November 2024 Pickering E. C. Yendell P. S. The supposedly variable star Y Aquilae Astrophysical Journal June 1898 8 57–59 1898ApJ.....8...57P 10.1086/140496 https://articles.adsabs.harvard.edu/pdf/1898ApJ.....8...57P 24 November 2024 Breinhorst Robert Arnold 1966PhDT.......142B Der veränderliche Y Aquilae: lichtelektrische Dreifarbenphotometrie zur Untersuchg der System-Eigenschaften 1966 University of Bonn Muller G. Kempf P. Number 31. Neunter Band. Photometrische Durchmusterung des Nordlichen Himmels, anthaltend alle sterne der B.D. bis zur Grosse 7.5. Theil I. Zone 0 degrees bis + 20 degrees declination Publikationen des Astrophysikalischen Observatoriums zu Potsdam 1894 9 1–501 1894POPot...9....1M https://articles.adsabs.harvard.edu/pdf/1894POPot...9....1M 24 November 2024 1980Ap&SS..68..433D Close Binary Systems Before and after Mass Transfer - a Comparison of Observations and Theory De Greve J. P. Vanbeveren D. Astrophysics and Space Science 1980 68 2 433 10.1007/BF00639709 123281741 MAST: Barbara A. Mikulski Archive for Space Telescopes https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html Space Telescope Science Institute 8 December 2021 F. van Leeuwen Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653–664 2007A&A...474..653V 10.1051/0004-6361:20078357 free 0708.1752 November 2007 18759600 Levato H. Rotational velocities and spectral types for a sample of binary systems Astronomy and Astrophysics Supplement Series 19 91–99 1975A&AS...19...91L January 1975 Wilson Ralph Elmer 1953 General catalogue of stellar radial velocities Carnegie Institute Washington D.C. Publication Carnegie Institution of Washington 1953GCRV..C......0W Osawa K. Hata S. Three-color photometry of B8-A2 stars (II). Annals of the Tokyo Astronomical Observatory 7 209 1962 1962AnTok...7..209O Tokovinin Andrei 2018-03-01 The Updated Multiple Star Catalog The Astrophysical Journal Supplement Series 235 1 6 10.3847/1538-4365/aaa1a5 0067-0049 1712.04750 2018ApJS..235....6T 119047709 free Eggleton P. P. Tokovinin A. A. A catalogue of multiplicity among bright stellar systems Monthly Notices of the Royal Astronomical Society 389 2 869–879 10.1111/j.1365-2966.2008.13596.x 2008MNRAS.389..869E 0806.2878 September 2008 free 14878976 18 Aql 2012-07-25 Tetzlaff N. Neuhäuser R. Hohle M. M. A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun Monthly Notices of the Royal Astronomical Society 410 1 190–200 10.1111/j.1365-2966.2010.17434.x 2011MNRAS.410..190T 1007.4883 January 2011 free 118629873 1 Malkov O. Yu. Oblak E. Snegireva E. A. Torra J. A catalogue of eclipsing variables Astronomy and Astrophysics 446 2 785–789 10.1051/0004-6361:20053137 2006A&A...446..785M February 2006 free 10995/73280 free 2009yCat....102025S 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 etal Samus N. N. Durlevich O. V. 2009 External links Image 18 Aquilae HR 7248 Category:Aquila (constellation) Category:Eclipsing binaries Category:Spectroscopic binaries Category:Triple star systems Aquilae, 18 Aquilae, Y 178125 7248 093867 BD+10 3787 Category:B8III stars