YONSEI EVOLUTIONARY POPULATION SYNTHESIS (YEPS) MODEL. I. SPECTROSCOPIC EVOLUTION OF SIMPLE STELLAR POPULATIONS

Journal Article · Tue Jan 15 04:00:00 EST 2013 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/204/1/3· OSTI ID:22089715

Chung, Chul; Yoon, Suk-Jin; Lee, Sang-Yoon; Lee, Young-Wook ^[1]

---

1. Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

We present a series of papers on the 2012 version of the Yonsei Evolutionary Population Synthesis (YEPS) model, which was constructed based on over 20 years of research. This first paper delineates the spectroscopic aspect of integrated light from stellar populations older than 1 Gyr. The standard YEPS is based on the most up-to-date Yonsei-Yale stellar evolutionary tracks and BaSel 3.1 flux libraries, and provides absorption line indices of the Lick/IDS system and high-order Balmer lines for simple stellar populations as functions of stellar parameters, such as metallicity, age, and {alpha}-element mixture. Special care has been taken to incorporate a systematic contribution from horizontal-branch (HB) stars, which alters the temperature-sensitive Balmer lines significantly, resulting in up to a 5 Gyr difference in the age estimation of old, metal-poor stellar populations. We also find that HBs exert an appreciable effect not only on the Balmer lines but also on the metallicity-sensitive lines, including the magnesium index. This is critical in explaining the intriguing bimodality found in index distributions of globular clusters in massive galaxies and to accurately derive spectroscopic metallicities from various indices. A full set of the spectroscopic and photometric YEPS model data of the entire parameter space is currently downloadable at http://web.yonsei.ac.kr/cosmic/data/YEPS.htm.

• OSTI ID: 22089715
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 1 Vol. 204; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
AGE ESTIMATION
ASTROPHYSICS
BALMER LINES
EMISSION SPECTROSCOPY
GALAXIES
INDEXES
MAGNESIUM
PHOTOMETRY
SPACE
STAR EVOLUTION
STAR MODELS
STARS
VISIBLE RADIATION