A DIRECT STELLAR METALLICITY DETERMINATION IN THE DISK OF THE MASER GALAXY NGC 4258
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
- Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstr. 25/8, A-6020 Innsbruck (Austria)
- George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843-4242 (United States)
We present the first direct determination of a stellar metallicity in the spiral galaxy NGC 4258 (D = 7.6 Mpc) based on the quantitative analysis of a low-resolution (∼5 Å) Keck Low Resolution Imaging Spectrograph spectrum of a blue supergiant star located in its disk. A determination of stellar metallicity in this galaxy is important for the absolute calibration of the Cepheid period-luminosity relation as an anchor for the extragalactic distance scale and for a better characterization of its dependence as a function of abundance. We find a value 0.2 dex lower than solar metallicity at a galactocentric distance of 8.7 kpc, in agreement with recent H II region studies using the weak forbidden auroral oxygen line at 4363 Å. We determine the effective stellar temperature, gravity, luminosity, and line-of-sight extinction of the blue supergiant being studied. We show that it fits well on the flux-weighted gravity-luminosity relation, strengthening the potential of this method as a new extragalactic distance indicator.
- OSTI ID:
- 22364091
- Journal Information:
- Astrophysical Journal Letters, Vol. 779, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
EXTRAGALACTIC CHEMICAL ABUNDANCES: DO H II REGIONS AND YOUNG STARS TELL THE SAME STORY? THE CASE OF THE SPIRAL GALAXY NGC 300
Quantitative spectroscopy of blue supergiants in metal-poor dwarf galaxy NGC 3109