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The distance and metallicity of the newly discovered, nearby irregular galaxy HIZSS 3

Silva, David R. and Massey, Philip and DeGioia-Eastwood, Kathleen and Henning, P. A. (2005) The distance and metallicity of the newly discovered, nearby irregular galaxy HIZSS 3. Astrophysical Journal, 623 (1). pp. 148-158. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1086/428341


HIZSS 3 is an H I source in the Zone of Avoidance. Its radio characteristics are consistent with it being a previously unknown, nearby ( similar to 1.8 Mpc), low-mass dwarf irregular (dIrr) galaxy. Optical observations have shown that it contains a modest H II region, but they failed to reveal a resolved stellar population. New spectroscopic observations of the H II region obtained at the MMT Observatory are presented here. They are used to derive the line-of-sight extinction [E( B - V) = 1.41 +/- 0.04] and gas metallicity (log O/H +12 similar to 7.8) of the H II region. New near-IR imaging observations obtained at the ESO Very Large Telescope are also presented here. These images clearly reveal the resolved stellar population of HIZSS 3 for the first time. Narrowband Pa beta images of the H II region are used in combination with previously published H alpha data to obtain an independent line-of-sight extinction estimate: E(B - V) = 1.32 +/- 0.04. The adopted foreground extinction is E(B - V) = 1.36 +/- 0.06. Using the K-band luminosity function and K; J - K color-magnitude diagram, the apparent magnitude and color of the tip of the red giant branch are derived. In turn, these parameters are combined with the adopted foreground extinction to estimate the distance ( 1.69 +/- 0.07 Mpc) and mean red giant branch metallicity ([Fe/H] = - 0.5 +/- 0: 1). As an ensemble, these new observations significantly strengthen the conclusion that HIZSS 3 is a newly discovered low-mass dIrr galaxy lurking behind the Milky Way in the outskirts of the Local Group.

Item Type: Article
Publisher’s Statement: © 2005 The American Astronomical Society. Published by IOP Publishing.
ID number or DOI: 10.1086/428341
Keywords: abundances; color-magnitude diagrams; galaxies : dwarf; galaxies : individual (HIZSS 3); galaxies : irregular; h-ii regions; milky-way; red giant branch; southern galaxies; tip
Subjects: Q Science > QB Astronomy
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 30 Sep 2015 17:49
URI: http://openknowledge.nau.edu/id/eprint/428

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