EDP Sciences
Free access
Issue
A&A
Volume 373, Number 1, July I 2001
Page(s) 56 - 62
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010598


A&A 373, 56-62 (2001)
DOI: 10.1051/0004-6361:20010598

The oxygen abundance distribution in M 101

L. S. Pilyugin

Main Astronomical Observatory of National Academy of Sciences of Ukraine, Goloseevo, 03680 Kiev-127, Ukraine

(Received 15 March 2001 / Accepted 23 April 2001 )

Abstract
The well-observed spiral galaxy M 101 was considered. The radial distributions of oxygen abundances determined in three different ways (with the classic $T_{\rm e}$-method, with the R23-method, and with the P-method) were compared. It was found that the parameters (the central oxygen abundance and the gradient) of the radial (O/H)P abundance distribution are close to those of the (O/H) $_{T_{\rm e}}$ abundance distribution. The parameters of the (O/H)R23 abundance distribution differ significantly from those of the (O/H) $_{T_{\rm e}}$ abundance distribution: the central (O/H)R23 oxygen abundance is higher by around 0.4 dex and the gradient is steeper by a factor of around 1.5 as compared to those values in the (O/H) $_{T_{\rm e}}$ abundance distribution. The dispersion in (O/H)P abundance at fixed radius is rather small, ~0.08 dex, and is equal to that in (O/H) $_{T_{\rm e}}$ abundance. The dispersion in (O/H)R23 abundance at fixed radius is appreciably larger, ~0.16 dex, compared to that in (O/H) $_{T_{\rm e}}$ abundance. It has been shown that the extra dispersion in (O/H)R23 abundances is an artifact and reflects scatter in excitation parameter P at fixed radius.


Key words: galaxies: abundances -- galaxies: ISM -- galaxies: spiral -- galaxies: individual: M 101

Offprint request: L. S. Pilyugin, pilyugin@mao.kiev.ua

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