HD 153720 – A SB2 system with twin metallic-line components

• Published in: Astronomy and astrophysics (Berlin) Vol. 425; no. 1; pp. 171 - 177
• Main Authors: Yushchenko, A. V., Gopka, V. F., Khokhlova, V. L., Lambert, D. L., Kim, C., Kang, Y. W.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.10.2004
• Subjects: stars: abundances; stars: atmospheres; stars: binaries: spectroscopic; stars: chemically peculiar; stars: evolution; stars: individual: HD 153720; stars: atmospheres; stars: evolution; Effective temperature; Rotation speed; stars: binaries: spectroscopic; Stellar abundance; Stellar evolution; stars: individual: HD 153720; Metallic line stars; stars: abundances; Noise spectrum; Surface gravity; Radial velocity; stars: chemically peculiar; Chemically peculiar star; Spectroscopic binary stars
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20035922

We report the results of abundance determinations for the components of the SB2 star HD 153720 from high resolution ($R=60\,000$) echelle high signal-to-noise spectra of the wavelength region 3595-10 260 Å  taken with the 2.7 m telescope of the McDonald Observatory We found the values of the atmospheric parameters of the primary to be effective temperature $T_{{\rm eff}}$ = 7425 K and surface gravity $\log\,g$ = 4.0 cgs, and of the secondary to be $T_{{\rm eff}}$ = 7125 K and $\log\,g$ = 3.9 cgs. The microturbulent velocity is $v_{{\rm micro}}$ = 2.7 ${{\rm km~s^{-1}}}$ for both components, and the projected rotational velocity is ${v\sin i}$  = 15 ${{\rm km~s^{-1}}}$  also for both components. The abundances of about 20 elements were determined with the method of spectrum synthesis. The components of HD 153720 are metallic-line stars. Possible inconsistencies between old and new measurements of radial velocities may be explained by the existence of third body in this system. A review of recent high resolution spectral observations of eight A4-F1 binaries shows that only one of these systems can be classified as normal.