The Star Formation Histories and Efficiencies of Two Giant H II Regions in M33

Wilson, C. D.; Matthews, B. C.

doi:10.1086/176561

Cited by 30 publications

(30 citation statements)

References 16 publications

(37 reference statements)

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“…The former has an upper limit based upon the crossing time, which for dwarfs is ∼2 10 8 yr, while latter will take place on a time scale of a few ×10 7 yr. Verter & Hodge assumed SF = 1 to obtain lower limits on N H2 , but a more accurate value is 0.02 (e.g. Taylor et al 1999 for the post-starburst dwarf galaxy NGC 1569, Wilson & Matthews 1995 for the giant HII regions NGC 604 and NGC 595 in M 33). We will estimate Taylor et al (1998), with the data point for WLM from this paper added the column density with both efficiencies since this is the least secure property used in the calculation.…”

Section: Discussionmentioning

confidence: 99%

A search for CO in the Local Group dwarf irregular galaxy WLM

Taylor

Klein

2001

A&A

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Abstract. We present 12 CO J = 1 → 0 and J = 2 → 1 observations of the low metallicity (12 + log(O/H) = 7.74) Local Group dwarf irregular galaxy WLM made with the 15 m SEST and 14 m FCRAO telescopes. Despite the presence a number of HII regions, we find no CO emission. We obtain low upper limits on the integrated intensity (ICO ≤ 0.18 K km s −1 for CO (1 → 0)). The non-detection is consistent with the result of Taylor, Kobulnicky & Skillman (1998), that dwarf galaxies below a metallicity of ∼7.9 are not detected in CO emission. WLM shows that this trend continues for low metallicity galaxies even as their metallicities approach 7.9. These results are consistent with the models of the metal poor ISM by Norman & Spaans (1997). By comparing our CO data with observations of star formation in WLM, we find evidence for a high CO to H2 conversion factor.

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Section: Discussionmentioning

confidence: 99%

A search for CO in the Local Group dwarf irregular galaxy WLM

Taylor

Klein

2001

A&A

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“…It is a young star forming region with an age of 3-5 Myr (e.g., Wilson & Matthews 1995;Pellerin 2006). Located some 12…”

Section: Spitzer Mid-ir Variability Surveymentioning

confidence: 99%

The UK Infrared Telescope M33 monitoring project – IV. Variable red giant stars across the galactic disc

Javadi

Saberi

Loon

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. In this fourth paper of the series, we present a search for variable red giant stars in an almost square degree region comprising most of the galaxy's disc, carried out with the WFCAM instrument in the K band. These data, taken during the period 2005-2007, were complemented by J-and H-band images. Photometry was obtained for 403 734 stars in this region; of these, 4643 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. The variable stars are concentrated towards the centre of M 33, more so than low-mass, less-evolved red giants. Our data were matched to optical catalogues of variable stars and carbon stars and to mid-infrared photometry from the Spitzer Space Telescope. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey. The photometric catalogue is made publicly available at the Centre de Données astronomiques de Strasbourg.

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“…NGC 604 is the first nearby giant H ii region we have investigated for this purpose. It is a young star-forming region in the dwarf spiral galaxy M 33 with an age of 3-5 Myr (e.g., D'Odorico & Rosa 1981; Wilson & Matthews 1995;Pellerin 2006). NGC 604 is the brightest extragalactic H ii region in the sky after 30 Doradus.…”

Section: Introductionmentioning

confidence: 99%

Interstellar abundances in the neutral and ionized gas of NGC 604

Lebouteiller¹,

Kunth²,

Lequeux

et al. 2006

A&A

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Aims. We present FUSE spectra of the giant H ii region NGC 604 in the spiral galaxy M 33. Chemical abundances are tentatively derived from far-UV absorption lines and compared to those derived from optical emission lines. Methods. Absorption lines from neutral hydrogen and heavy elements were observed against the continuum provided by the young massive stars embedded in the H ii region. We derived the column densities of H i, N i, O i, Si ii, P ii, Ar i, and Fe ii, fitting the line profiles with either a single component or several components. We used CLOUDY to correct for contamination from the ionized gas.Archival HST/STIS spectra across NGC 604 allowed us to investigate how inhomogeneities affect the final H i column density. Results. Kinematics show that the neutral gas is physically related to the H ii region. The STIS spectra reveal H i column density fluctuations up to 1 dex across NCG 604. Nevertheless, we find that the H i column density determined from the global STIS spectrum does not differ significantly from the average over the individual sightlines. Our net results using the column densities derived with FUSE, assuming a single component, show that N, O, Si, and Ar are apparently underabundant in the neutral phase by a factor of ∼10 or more with respect to the ionized phase, while Fe is the same. However, we discuss the possibility that the absorption lines are made of individual unresolved components, and find that only P ii, Ar i, and Fe ii lines should not be affected by the presence of hidden saturated components, while N i, O i, and Si ii might be much more affected.Conclusions. If N, O, and Si are actually underabundant in the neutral gas of NGC 604 with respect to the ionized gas, this would confirm earlier results obtained for the blue compact dwarfs, and their interpretations. However, a deeper analysis focused on P, Ar, and Fe mitigates the above conclusion and indicates that the neutral gas and ionized gas could have similar abundances.

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The Star Formation Histories and Efficiencies of Two Giant H II Regions in M33

Cited by 30 publications

References 16 publications

A search for CO in the Local Group dwarf irregular galaxy WLM

A search for CO in the Local Group dwarf irregular galaxy WLM

The UK Infrared Telescope M33 monitoring project – IV. Variable red giant stars across the galactic disc

Interstellar abundances in the neutral and ionized gas of NGC 604

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