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Spectroscopy of candidate young globular clusters in NGC 1275We present spectra of the brightest member of the population of compact blue objects discovered in the peculiar galaxy NGC 1275 by Holtzman et al. (1992) using Hubble Space Telescope images. These spectra show strong Balmer absorption lines like those observed in A-type stars, as expected if the object is a young globular cluster. The age estimated from the strength of the Balmer lines is about 0.5 Gyr, although ages ranging from 0.1 Gyr to 0.9 Gyr cannot be confidently excluded given current models of stellar populations. If these estimated ages are adopted for the young cluster population of NGC 1275 as a whole, the fading predicted by stellar populations models gives a luminosity function which is consistent with that of the Galactic globular cluster system convolved with the observational selection function for the NGC 1275 system. We also use the equivalent widths of the Mg b and Fe 5270 features to constrain the metallicity of the young cluster. Combining these absorption-line widths with the age estimates from the Balmer lines and stellar population models, we find a metallicity of roughly solar, based on the Mg b index, and somewhat higher for the Fe 5270 index. The radial velocity of the absorption lines of the cluster spectrum is offset from the emission lines of the galaxy spectrum at the same position by - 130 km/s, providing further evidence for the identification of the object as a global cluster and opening up the future possibility of studying the kinematics of young cluster systems. The discovery of objects with the characteristics of young globular clusters in NGC 1275, which shows evidence of a recent interaction or merger, supports the hypothesis that galaxy interactions and mergers are favorable sites for the formation of globular clusters.
Document ID
19950056275
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Zepf, Stephen E.
(University of California, Berkeley, California United States)
Carter, Dave
(Royal Greenwich Observatory, Cambridge, England GB, United States)
Sharples, Ray M.
(University of Durham, Durham, England GB, United States)
Ashman, Keith
(University of Kansas, Lawrence, Kansas United States)
Date Acquired
August 16, 2013
Publication Date
May 20, 1995
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 445
Issue: 1
ISSN: 0004-637X
Subject Category
Space Radiation
Accession Number
95A87874
Funding Number(s)
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Other

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