Diapositiva 1

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(Metallicities and) gradients in dwarf spiral
galaxies
A.M. Hidalgo-Gámez (ESFM-IPN) D. Ramírez-Fuentes
(IA-UNAM) J. Gónzalez (IA-UNAM)
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UGC 6205
UGC 5242
UGC 5296
UGC 6377
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There are no more!!!
Hidalgo-Gàmez 2004 Hidalgo-Gàmez et al., in
preparation
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The grating was the 300 lines mm-1 with a
nominal resolution of 7 Å and a spectral
coverage of 3500-6900 Å. The seeing was about 1.5"
The spectra were obtained at March 2002 using
the BCh at the 2.1m telescope of the OAN at
San Pedro Mártir
Two or three slit positions, with two or three
integrations each, were considered for each
galaxy in order to cover the larger number of
HII regions.
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Problems
(Due to lack of efficiency of the
spectrograph)? the real spectral coverage was
4000-6900 Å
So, what about OII3726-3729Å
We used the relation between OIII5007Å and
OII3727Å (Kobulnicky et al. 1999)? determined
from a sample of star forming galaxies
(Ramírez-Fuentes, Master Thesis)?
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Log(OII/Hß) -2.821 log(OIII/Hß)2 2.392
log(OIII/Hß) -0.0542
The largest uncertainties are about 35 in the
intensity of OII
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Problems
(Due to lack of efficiency of the
spectrograph)? the real spectral coverage was
4000-6900 Å
The chemical abundances could not be determined
from the electronic temperature but for only one
HII region
The McGaugh (1991) calibration of the R23, and
the new calibration (2005) of the P parameter
were used as well as the Denicoló et al. (2002)
calibration of the N2 and the Pettini Pagel
(2004) calibration (N3) when the nitrogen lines
were detected.
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more problems!
Both, the R23 and the P methods are bi-valuated
If log(NII/OII) gt -1, the region is of high
metallicity.
But, N is not in all the spectra and the
intensity of OII is quite uncentain!!!
It is not so straightforward!!
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Concerning the metallicity.

• The metallicity of UGC 5242 is slightly smaller
  than the value for the LMC

UGC5296a1 is one of the regions with the lowest
metallicity in spiral galaxies 12log(O/H)
7.4 dex
Five of the HII regions of UGC 6205 have over
solar abundances, but only two of them might
have (indications of) shocks.
Two of the regions of UGC 6377 have very large
abundances, specially the N2 and N3 values
(PN?).
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UGC 6205
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R23 and P
N2 and N3
Zave
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UGC 6377
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R23 and P
N2 and N3
Zave
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UGC 5242
UGC 5296
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Are these values real?
UGC 5296
UGC 5242
UGC 6377
UGC 6205
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Are these values real?

• UGC 5296
• ? UGC 6377
• ? UGC 6205
• ? UGC 5242

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Are these values real?

• UGC 5296
• ? UGC 6377
• ? UGC 6205
• ? UGC 5242

Metallicity decreases (Asari et al. 2007)?
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Comparison with other late-type galaxies
Data on surface brightness, Mb, size, gass mas
(HI) and surface density for 8 non-barred and 7
barred late-type (Scd, Sd and Sm) from Martin
Roy (94), Vila-Costas Edmunds (92), Zaristky
et al. (94) and van Zee et al. (99).
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Conclusions
The barred dwarf galaxies have similar gradients
that the non-dwarf ones.
Although the large gradient, UGC 6377 fits the
relationships for non-barred galaxies
The gradient of UGC 6205 might be slightly
smaller (-0.3) and the one of UGC 5296 might be
larger (-0.2).
Are there two different types of Sm?
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Astronomer wanted!!
The Escuela Superior de Fìsica y Matemàticas at
Mexico city offers a faculty position of
teacher/researcher in Observational/instrumental
Astronomy.
Those interested, please, send a detailed CV and
a reseach interest letter to ahidalgo_at_esfm.ipn.mx
before September 1st.
For more information, please, contact Ana
Hidalgo-Gàmez at this meeting.
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Diagnostic diagrams
? Sm (McCall 1983)? ? dS (H-G 2004)? ? Im dS
(this work)? x AGN (McCall 1983)?
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