Discovery of a nitrogen-rich UV-bright star in the globular cluster M5

Journal Article · Fri Apr 15 00:00:00 EST 1983 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/184009· OSTI ID:5984475

Bohlin, R C; Cornett, R H; Hill, J K; Smith, A M; Stecher, T P; Sweigart, A V

Ultraviolet images of the globular cluster M5 (NGC 5904) obtained with a rocket-borne telescope show a hot and luminous star approx.20'' from the cluster center. Spectra of this UB-bright star, obtained with the International Ultraviolet Explorer satellite in the low-resolution mode, reveal an energy distribution very similar to that of ..mu.. Col, a Population I O9.5 IV star with T/sub eff/ = 35,000 K and log g = 4.19, except for the absence of metallic line blanketing. Assuming an effective temperature of 35,000 K for the UV-bright star, we find L = 1800 L/sub sun/, M/sub bol/ = -3.40, R = 1.15 R/sub sun/, and log g = 4.04. The N V lambda1240 line is much stronger in the UV-bright star than in ..mu.. Col, indicating that the CNO cycle has converted the envelope C and O into N. A single emission line at the wavelength of the N IV intercombination line is also present, suggesting the possible existence of a planetary nebula. The mass-luminosity relation for asymptotic giant branch stars gives M = 0.53 M/sub sun/, imply a mass of 0.08 M/sub sun/ since the horizontal-branch phase.

• Research Organization: Laboratory for Astronomy and Solar Physics, Goddard Space Flight Center, Greenbelt, Maryland
• OSTI ID: 5984475
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Vol. 267:2
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
MAIN SEQUENCE STARS
STAR CLUSTERS
ULTRAVIOLET SPECTRA
LUMINOSITY
MASS
NITROGEN
STAR EVOLUTION
ELEMENTS
NONMETALS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources