EDP Sciences
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Volume 376, Number 3, September IV 2001
Page(s) 793 - 802
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20011018

A&A 376, 793-802 (2001)
DOI: 10.1051/0004-6361:20011018

High K-band surface brightness fluctuations in NGC 1427 and NGC 720

S. Mei1, 2, M. KisslerPatig2, D. R. Silva2 and P. J. Quinn2

1  Observatoiren Midi-Pyrénées, 14 Av. E. Belin, 31400 Toulouse, France
2  European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany

(Received 31 October 2000 / Accepted 6 July 2001)

We have observed K-band Surface Brightness Fluctuations (SBF) in NGC 1427 and NGC 720. We combine our measurements with distance measurements based on I-band SBF distance moduli and distance moduli derived by other distance indicators. When using distances from I-band SBF, we obtain $\overline M_K =
-6.55 \pm 0.27$ for NGC 1427 and $\overline M_K = -6.43 \pm 0.18$ for NGC 720. When using an average of direct distance measurements, we obtain $\overline M_K = -6.17 \pm 0.23$ for NGC 1427 and $\overline M_K = -6.14
\pm 0.24$ for NGC 720. For both galaxies, $\overline M_K$ lies well above the average value used as a calibration for distance indication ( $\overline M_K = -5.61 \pm 0.12$ Jensen et al. 1998). In NGC 720 the high K-band SBF are most probably due to an intermediate-age population. However, there is no hint from current data for any anomaly in the stellar population of NGC 1427. These large variations of $\overline M_K$ in several galaxies underline once more the need for a better understanding of $\overline M_K$ as a function of stellar population properties (Mei et al. 2001b; Liu et al. 2001), especially with respect to the potential presence of intermediate-age populations.

Key words: galaxies: distances -- individual: NGC 1427, NGC 720

Offprint request: S. Mei, mei@ast.obs-mip.fr

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