Near-infrared spectra of 29 carbon stars: Simple estimates of effective temperature

作者：Tanaka Masuo^*; Letip Ahmatjan; Nishimaki Yuichirou; Yamamuro Tomoyasu; Motohara Kentaro; Miyata Takashi; Aoki Wako

来源：Publications of the Astronomical Society of Japan, 2007, 59(5): 939-953.

• infrared : stars
• stars : carbon
• techniques : spectroscopic

Near-infrared spectra of 29 carbon stars in the 0.9-2.4 mu m range were obtained by using a cross-dispersed echelle spectrograph. The target stars, which were classified into C-H, C-R, C-J, and C-N types, were selected from an atlas of Barnbaum, Stone, and Keenan (1996, ApJS, 105, 419). Because the stars are non long-period variables, the phase differences of the light curves do not strongly affect the spectra. The effective temperatures (T-eff) of the carbon stars were estimated with errors of +/- 200 K by fitting our spectra at wavelengths of 1.35, 1.74, and 2.29,mu m, with simple model spectra, while considering the H- opacity minimum to be around 1.6 mu m. At these wavelengths, molecular absorption due to CO, CN, and C-2 is not strong. The derived effective temperatures are distributed between 5 100 K and 2600 K, and highly correlate with the temperature sequence in Barnbaum, Stone, and Keenan (ibid.), although the stars with temperature sequences beyond 4 have similar temperatures near similar to 3000 K. We also compared our results with values derived by other methods in the literature: the aperture diameter method, the infrared flux method, and some model calculations.

• 出版日期2007
• 单位中国科学院国家天文台