Evolution of optical spectral index and variability properties of S5 0716＋714

• Published in: Research in astronomy and astrophysics 2010-02, Vol.10 (2), p.125-134, Article 125
• Main Authors: Hao, Jian-Ming, Wang, Bai-Juan, Jiang, Ze-Jun, Dai, Ben-Zhong
• Format: Article
• Language: English
• Subjects: Lac天体; 光学波段; 光学观测; 光谱参数; 光谱指数; 性能变化; 时间尺度
• ISSN: 1674-4527; 2397-6209
• DOI: 10.1088/1674-4527/10/2/003

We analyze the spectral variability and spectral evolution in the optical en- ergy region by using multiband （BVRI） optical observations of S5 0716＋714 spanning 1994 to 2005. The spectrum hardens when the source becomes brighter, which is con- sistent with general BL Lac objects. The spectral evolution parameter implies that the spectral variability is small in optical bands over 10 years. A simple model represent- ing the variability of a synchrotron component can explain the spectral changes. In addition, we employ the z-transformed discrete correlation function （ZDCF） to ana- lyze the optical multiband flux correlation. The long-term light curve behavior reveals that the variability time scales are 3.5 yr in the B-band, 3.3 yr in the V-band, 3.4 yr in the R-band and 3.5 yr in the/-band. The time lags between any two optical bands were not found when considering statistical errors.