A Spectroscopic Study of the Close Binary AG Virginis

• Main Authors: Ho-Il Kim, Chung-Uk Lee, Jae Woo Lee, Mi Rim Sohn
• Format: Article
• Language: English
• Published: Korean Space Science Society (KSSS) 2005-12-01
• Series: Journal of Astronomy and Space Sciences
• Subjects: eclipsing binary; AG Vir; spectroscopy; radial velocity; absolute dimension; light-time effect; system velocity
• Online Access: http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2005/v22n4/OJOOBS_2005_v22n4_353.pdf

We performed a new high-resolution spectroscopy of AG Vir for 4 nights from 25 March 2004 using the BOES (Bohyunsan Optical Echelle Spectrograph) attached to the 1.8-m reflector at Bohyunsan Optical Astronomy Observatory, and obtained a total of 59 spectra where all orbital phases are covered. To get the radial velocities of the binary system, both method of the CCF (Cross-Correlation Function)and the BF (Broadening Function) were applied to the analysis of all the observed spectra. From these, the CCF could calculate the radial velocities of the primary star alone, while the BF could determine those of the primary and the secondary components. New absolute dimensions were deduced with the combination of our spectroscopic orbital elements (K1=90.5km/s-1 K2=258.8) and the photometric solutions of Bell, Rainger, & Hilditch (1990): M1=1.99 M⊙, M2=0.62 M⊙, R1=2.21 R⊙, R2=1.36 R⊙, L1=13.17 L⊙, and L2= 3.47 L⊙. Our absolute parameters are larger and brighter than those derived from Bell, Rainger, & Hilditch (1990). We re-analyzed all the previous radial-velocity curves of AG Vir and, as a result, can see that its system velocity scatters largely up to ± 8km/s. However, we, at present, cannot determine this as the light-time effect due to the third body, which was suggested as a cause of the orbital period changes by Qian (2001).