2001/06/27 by R. D. Blum, Robert Blum, D. Schaerer +7
Chemistry · Engineering · Physics and Astronomy · #Advanced Fiber Laser Technologies #Photonic Crystal and Fiber Optics #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.1086/323096
latex, 33 pages including nine figures. Accepted for publication in the Astronomical Journal
arxiv created 2001/06/27 · openalex publication_date 2001/10/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Canada-France-Hawaii-Telescope adaptive optics bonnette images through narrow-band filters in the K-band are presented for the Arches cluster. Continuum fluxes, line fluxes, and equivalent widths are derived from high angular resolution images, some near diffraction limited, for the well known massive stars in the Arches cluster. Images were obtained in the lines of \ionHe1 2.06 \mic, \ionH1 Brγ (2.17 \mic), and \ionHe2 2.19 \mic as well as continuum positions at 2.03 \mic, 2.14 \mic, and 2.26 \mic. In addition, fluxes are presented for \ionH1 Pα (1.87 \mic) and a nearby continuum position (1.90 \mic) from Hubble Space Telescope archival data. The 2 \mic and Pα data reveal two new emission-line stars and three fainter candidate emission-line objects. Indications for a spectral change of one object between earlier observations in 1992/1993 and our data from 1999 are found. The ratio of \ionHe2 2.19 \mic to Brγ emission exhibits a narrow distribution among the stars, suggesting a narrow evolutionary spread centered predominantly on spectral types O4 If or Wolf-Rayet stars of the WN7 sub-type. From the approximate spectral types of the identified emission-line stars and comparisons with evolutionary models we infer a cluster age between ∼ 2 and 4.5 Myr.