Distributions, equivalent widths and metallicities of the HII regions in the spiral galaxies NGC 5457 and NGC 4395

Cedrés, B.; Cepa, J.

doi:10.1051/0004-6361:20020588

Cited by 36 publications

(72 citation statements)

References 31 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 Cedrés & Cepa (2002). The change in slope (compared to the T e data for 12 + log(O/H) < 8.4) is clear in Fig.…”

Section: Resultsmentioning

confidence: 80%

“…Kennicutt et al (2003) data (columns three and five). The equivalent widths from Kennicutt et al (2003) were derived assuming a value for the continua equal to those measured by Cedrés & Cepa (2002). In Table 2 we present the abundance derived for the coincidental regions.…”

Section: Resultsmentioning

confidence: 99%

“…The data have been taken from Cedrés & Cepa (2002). These data were obtained using the direct imaging method through narrow band filters.…”

Section: Datamentioning

confidence: 99%

“…The observational methods and the reduction and calibration processes are described in Cedrés & Cepa (2002). All the regions are extinctioncorrected and the Hβ line is also corrected for underlying absorption (Cedrés & Cepa 2002 (Kennicutt et al 2003), and to be sure that all the regions were in the high metallicity regime, thus avoiding uncertainties due to the low metallicity branch of Pilyugin's (2001a) calibration. Our cut off is approximately 0.2 dex over the limit indicated by Pilyugin (2001a).…”

Section: Datamentioning

confidence: 99%

“…There are different calibrations using the R 23 ratio, such as those of Dopita & Evans (1986), Edmunds & Pagel (1984), McCall et al (1985), McGaugh (1991) or Zaritsky et al (1994). However, this indicator presents one great disadvantage: the derived abundances depend strongly on the R 23 -O /H calibration (Kewley & Dopita 2002;Cedrés 2003). Moreover, for M 101 Kennicutt et al (2003) have recently found systematic differences up to a factor 3 between abundances derived from some empirical calibrations and those derived from the direct method, the latter being lower.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The oxygen abundance gradient in M 101: The reliability of thePmethod

Cedrés

Urbaneja

Cepa

2004

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. We present the oxygen abundance determination for 90 H  regions in the inner parts of the grand design galaxy M 101. The abundances were derived employing the P method (Pilyugin 2001a). A comparison is made with previous determinations using another calibration and direct measurements of electron temperature to derive the oxygen abundance. The results show agreement with the abundances derived from the electron temperature method and also show that the older calibration is not as accurate as the P method.

show abstract

“…1 Cedrés & Cepa (2002). The change in slope (compared to the T e data for 12 + log(O/H) < 8.4) is clear in Fig.…”

Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

“…The data have been taken from Cedrés & Cepa (2002). These data were obtained using the direct imaging method through narrow band filters.…”

Section: Datamentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The oxygen abundance gradient in M 101: The reliability of thePmethod

Cedrés

Urbaneja

Cepa

2004

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

Cedrés

Cepa

Bongiovanni

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We present here two H II region catalogues with azimuthal resolution for the two grand design galaxies NGC 628 and NGC 6946. With the help of these catalogues, we study several properties of the star-forming processes occurring in spiral galaxies. Methods. We obtained direct imaging in the narrow-band filters centred at Hα, Hβ, [O II]λ3727, and [O III]λλ4959, 5007 and their respective continua. After the calibration and correction of the data, we obtained for each H II region the de-reddened fluxes in the aforementioned lines, the size, the Hα equivalent width, and, using two different empirical calibrations, the metallicity. Employing a method based on the Delaunay triangulation, a two-dimensional (2D) representation of the metallicity was obtained. Results. Data for 209 H II regions of NGC 628 and 226 H II regions of NGC 6946 are obtained. The radial behaviours of the Hα equivalent width, the excitation, and the oxygen abundance are derived. Two-dimensional representations of the metallicity and the excitation are calculated for the galaxies in the study. The two empirical calibrations of the metallicity are compared. Conclusions. The behaviours of the extinction and the Hα equivalent width are similar to those presented in the literature. The oxygen abundance gradients obtained in this study agree with previously published values. However, more regions were examined than in previous studies. We find a difference of about 0.6 dex between the two empirical calibrations employed. Finally, the 2D representations of the metallicity reveal high metallicity knots in NGC 628, and for NGC 6946 a high metallicity azimuthal structure is discovered. These high metallicity regions seem to be linked to the arms of the galaxies and are probably produced by an increase in the temperature of the ionizing clusters in the H II regions, which may be linked to variations in the initial mass functions of the galaxies between the arm and interarm regions.

show abstract

No temperature fluctuations in the giant H II region H 1013

Stasińska

Morisset

Bresolin

et al. 2013

A&A

View full text Add to dashboard Cite

While collisionally excited lines in H ii regions allow one to easily probe the chemical composition of the interstellar medium in galaxies, the possible presence of important temperature fluctuations casts some doubt on the derived abundances. To provide new insights into this question, we have carried out a detailed study of a giant H ii region, H 1013, located in the galaxy M101, for which many observational data exist and which has been claimed to harbour temperature fluctuations at a level of t 2 = 0.03−0.06. We have first complemented the already available optical observational datasets with a mid-infrared spectrum obtained with the Spitzer Space Telescope. Combined with optical data, this spectrum provides unprecedented information on the temperature structure of this giant H ii region. A preliminary analysis based on empirical temperature diagnostics suggests that temperature fluctuations should be quite weak. However, only a detailed photoionization analysis taking into account the geometry of the object and observing apertures can make a correct use of all the observational data. We have performed such a study using the pyCloudy package based on the photoionization code Cloudy. We have been able to produce photoionization models constrained by the observed Hβ surface brightness distribution and by the known properties of the ionizing stellar population than can account for most of the line ratios within their uncertainties. Since the observational constraints are both strong and numerous, this argues against the presence of significant temperature fluctuations in H 1013. The oxygen abundance of our best model is 12 + log O/H = 8.57, as opposed to the values of 8.73 and 8.93 advocated by Esteban et al. (2009, ApJ, 700, 654) and Bresolin (2007, ApJ, 656, 186), respectively, based on the significant temperature fluctuations they derived. However, our model is not able to reproduce the intensities of the oxygen recombination lines observed by Esteban et al., as well as the very low Balmer jump temperature inferred by Bresolin. We have argued that the latter might be in error, due to observational difficulties. On the other hand, the discrepancy between model and observation as regards the recombination lines cannot be attributed to observational uncertainties and requires an explanation other than temperature fluctuations.

show abstract

Distributions, equivalent widths and metallicities of the HII regions in the spiral galaxies NGC 5457 and NGC 4395

Cited by 36 publications

References 31 publications

The oxygen abundance gradient in M 101: The reliability of thePmethod

The oxygen abundance gradient in M 101: The reliability of thePmethod

Two-dimensional metallicity distribution of the ionized gas in NGC 628 and NGC 6946

No temperature fluctuations in the giant H II region H 1013

Contact Info

Product

Resources

About