Beta Scuti Explained

Beta Scuti, Latinized from β Scuti, is a binary star system in the southern constellation Scutum. Based upon an annual parallax shift of 4.85 mas as seen from Earth, it is located approximately 670 light years from the Sun.

Characteristics

This is a spectroscopic binary with an orbital period of 2.3 years and eccentricity around 0.35.^[1] The secondary is about 3.3 magnitudes dimmer than the primary and estimated as type B9 based on the flux of far-ultraviolet radiation.^[2]

The primary component has an apparent visual magnitude of +4.22 and is radiating about 1,315 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 4,951 K. This yellow-hued star is a G-type bright giant with a stellar classification of G4 IIa. Its angular diameter was measured at 2.121milliarcseconds by the Navy Precision Optical Interferometer, which gives it a physical radius of approximately at the estimated distance.

The secondary was directly detected with a magnitude difference of 3.6 at a separation of about 17 milli-arcseconds using observations from the Navy Precision Optical Interferometer.^[3] This detection was significant as observations with the Hubble Space Telescope which indicated a companion star was present were not definitive.^[4] With an orbit and a parallax the sum of the masses of the two stars can be determined via a dynamical parallax.^[5] This eventually can yield a precise mass for the evolved giant primary star.

Beta Scuti was a latter designation of 6 Aquilae.^[6]

Notes and References

1. 2004A&A...424..727P . SB9: The ninth catalogue of spectroscopic binary orbits . Astronomy and Astrophysics . 424 . 2 . 727–732 . Pourbaix . D. . Tokovinin . A. A. . Batten . A. H. . Fekel . F. C. . Hartkopf . W. I. . Levato . H. . Morrell . N. I. . Nidia Morrell . Torres . G. . Udry . S. . 2004 . 10.1051/0004-6361:20041213 . astro-ph/0406573 . 119387088 .
2. 1998ApJS..119...83P. Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample. The Astrophysical Journal Supplement Series. 119. 1. 83. Parsons. Sidney B.. Ake. Thomas B.. 1998. 10.1086/313152. free.
3. 2016ApJS..227....4H . Surveying the Bright Stars by Optical Interferometry. I. A Search for Multiplicity among Stars of Spectral Types F-K . Astrophysical Journal Supplement Series . 227 . 4 . 1 . Hutter . D. J.. Zavala . R. T. . Tycner . C. . Benson . J. A. . Hummel . C. A. . Sanborn . J. . Franz . O. G. . Johnston . K. J. . 2016 . 10.3847/0067-0049/227/1/4 . 1609.05254 . 118803592 . free .
4. 2005AJ....129.1700P . The Fine Guidance Sensor Orbit of the G4 Bright Giant HD 173764 . Astronomical Journal . 129 . 3 . 1700 . Parsons . S. B.. Franz . O. G. . Wassermann . L. H.. 2005 . 10.1086/427853 . free .
5. Book: Heintz, Wulff D.. Double Stars - Springer. Geophysics and Astrophysics Monographs . en. 10.1007/978-94-009-9836-0. 1978GAM....15.....H. 1978. 15 . 978-90-277-0886-1.
6. Wagman . M. . Flamsteed's Missing Stars . Journal for the History of Astronomy . 18 . 3 . 212 . August 1987 . 1987JHA....18..209W . 10.1177/002182868701800305. 118445625 .