• Title/Summary/Keyword: NGC 185

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STAR FORMATION HISTORY AND DUST PRODUCTION: NGC147 AND NGC185

  • GOLSHAN, ROYA HAMEDANI;JAVADI, ATEFEH;VAN LOON, JACCO TH.;KHOSROSHAHI, HABIB G.
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.169-171
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    • 2015

  • NGC147 and NGC185, paired satellites of the Andromeda galaxy, possess the same order of mass and analogous structures, but they show different star formation and different amounts of interstellar gas and dust. Therefore, we present the first reconstruction of the star formation history of NGC147 and NGC185. Asymptotic Giant Branch stars are highly evolved stars that are brightest in K-band. This maximum K-band magnitude is related to the birth mass of stars. As a result, we have found a 9.9 Gyr old single star formation epoch for NGC185 followed by relatively continuous star formation. NGC147, however, has passed through two star formation episodes; one is as old as ~6 Gyr and the other is as recent as ~850 Myr. Asymptotic Giant Branch stars are also important dust factories; by fitting Spectral Energy Distributions to observed near and mid infrared data for each star, we were able to measure the dust production rates of individual stars; on order of $10^{-5}M_{\odot}yr^{-1}$. Hence, we estimate the total mass entering the interstellar medium to be $1.06{\times}10^{-4}M_{\odot}yr^{-1}$ and $2.89{\times}10^{-4}M_{\odot}yr^{-1}$ for NGC147 and NGC185.

  • https://doi.org/10.5303/PKAS.2015.30.2.169 인용 PDF KSCI

SURFACE PHOTOMETRY OF THE DWARF ELLIPTICAL GALAXIES NGC 185 AND NGC 205

  • KIM SANG CHUL;LEE MYUNG GYOON
    • Journal of The Korean Astronomical Society
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    • v.31 no.1
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    • pp.51-65
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    • 1998

  • We present B VRI CCD surface photometry for the central $(6'.35\times6'.35)$ regions of the dwarf elliptical galaxies NGC 185 and NGC 205 in the Local Group. Surface brightness profiles of NGC 185 (R<225') and NGC 205 (R<186') show excess components in the central regions. The colors of NGC 185 get bluer inward at R<25', while they remain constant at $R\geq25'$. The colors of NGC 205 get bluer inward at 1'$\approx10^5\; L_\bigodot$. Distributions of dust clouds in the central regions of the two galaxies are also investigated.

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The Near-IR TRGB Magnitude and Distance Modulus to NGC 185

  • Sohn, Y.J.;Kang, A.;Han, W.;Park, J.H.;Kim, H.I.;Kim, J.W.;Shin, I.G.;Chun, S.H.
    • Journal of Astronomy and Space Sciences
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    • v.25 no.3
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    • pp.245-248
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    • 2008

  • We determined values of distance modulus to nearby dwarf galaxy NGC 185 from the Tip of Red-Giant Branch (TRGB) method. Apparent magnitudes of the TRGB are estimated from the near-infrared JHK luminosity functions (LFs) of the resolved giant branch stars. Theoretical absolute magnitudes of the TRGB in near-infrared bands have been extracted from the Yonsei-Yale isochrones. The observed apparent and theoretical absolute magnitudes of the TRGB provide values of distance modulus to NGC 185 as (m - M) = $23.39{\pm}0.14$, $23.23{\pm}0.22$, and $23.27{\pm}0.26$ for J,H, and K bands, respectively. Distance modulus in bolometric magnitude is also derived as (m - M) = $23.62{\pm}0.12$.

  • https://doi.org/10.5140/JASS.2008.25.3.245 인용 PDF KSCI