Uncovering Additional Clues to Galaxy Evolution. I. Dwarf Irregular Galaxies in the Field

Lee, Henry; McCall, Marshall L.; Kingsburgh, R. L.; Ross, R. W.; Stevenson, Christopher L.

doi:10.1086/345384

Cited by 99 publications

(188 citation statements)

References 135 publications

(135 reference statements)

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“…As we can see, the majority of the galaxies show oxygen abundances lower than the expected by the closed-box models. The yield of oxygen that best fits our data (the effective yield) is y O = 0.003−0.005, in agreement with previous results found in the literature (i.e., Lee et al 2003;van Zee & Haynes 2006;Lee et al 2007). The sample galaxies are generally not well reproduced by the simple closed box model, and therefore inflow of pristine gas or outflow of enriched gas have played an important role in their chemical evolution.…”

Section: Comparison With the Closed-box Modelsupporting

confidence: 91%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

2010

A&A

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Aims. We performed a comprehensive analysis of a sample of 20 starburst galaxies that show a substantial population of very young massive stars, most of them classified as Wolf-Rayet galaxies. Methods. In this paper, the last in the series, we analyze the global properties of our galaxy sample using multiwavelength data extracted from our own observations (Hα fluxes, B and H-band magnitudes) and from the literature, which include X-ray, FUV, FIR, and radio (both H i spectral line and 1.4 GHz radio-continuum) measurements.Results. The agreement between our Hα-based star-formation rates (Sfr) and those provided by indicators at other wavelengths is remarkable, but we consider that the new Hα-based calibration provided by Calzetti et al. (2007, ApJ, 666, 870) should be preferred to older calibrations. The FUV-based Sfr provides a powerful tool for analyzing the star-formation activity on both global and local scales independently to the Hα emission. We provide empirical relationships between the ionized gas mass, neutral gas mass, dust mass, stellar mass, and dynamical mass with the B-luminosity. Although all mass estimations increase with increasing luminosity, we find important deviations to the general trend in some objects, which seem to be the consequence of their particular evolutionary histories. The analysis of the mass-to-light ratios give similar results. We investigate the mass-metallicity relations and conclude that both the nature and the star-formation history are needed to understand the relationships between both properties. The majority of the galaxies follow a Schmidt-Kennicutt scaling law of star-formation that agrees with that reported in individual star-forming regions within M 51 but not with that found in normal spiral galaxies. Dwarf galaxies seem to be forming stars more efficiently than the outskirts of spiral galaxies. We find a relation between the reddening coefficient and the warm dust mass indicating that the extinction is mainly internal to the galaxies. The comparison with the closed-box model also indicates that the environment has strongly affected their evolution. Conclusions. Considering all multiwavelength data, we found that 17 up to 20 galaxies are clearly interacting or merging with lowluminosity dwarf objects or H i clouds. The remaining three galaxies (Mkn 5, SBS 1054+364, and SBS 1415+437) show considerable divergences of some properties when comparing with similar objects. Many of the interacting/merging features are only detected when deep optical spectroscopy and a detailed multiwavelength analysis, including H i observations, are obtained. We conclude that interactions do play a fundamental role in the triggering mechanism of the strong star-formation activity observed in dwarf starburst galaxies.

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Section: Comparison With the Closed-box Modelsupporting

confidence: 91%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

2010

A&A

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“…1). In the past it was argued that the internal reddening was also negligible since background galaxies can be seen through IC 1613 (Hodge 1978;Freedman 1988;Krienke & Hodge 2000), although Hodge (1978) (Lee et al 2003), but reddening is suspected to be high and anomalous towards Wolf-Rayets. Detections of the molecular cloud, neutral hydrogen and dust by IRAS and Spitzer in the bubble region (Meaburn et al 1988;Jackson et al 2006) are further evidence of extinction in the area.…”

Section: Variable Extinction and Extinction Mapmentioning

confidence: 99%

The young stellar population of IC 1613

García¹,

Herrero

Vicente³

et al. 2009

A&A

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Context. Determining the parameters of massive stars is crucial to understand many processes in galaxies and the Universe, since these objects are important sources of ionization, chemical enrichment and momentum. 10m class telescopes enable us to perform detailed quantitative spectroscopic analyses of massive stars in other galaxies, sampling areas of different metallicity. Relating the stars to their environment is crucial to understand the physical processes ruling their formation and evolution. Aims. In preparation for the new instrumentation planned for the Gran Telescopio CANARIAS (GTC), our goal is to build a list of massive star candidates in the metal-poor irregular galaxy IC 1613. The catalogue must have very high astrometric accuracy, suitable for the current generation of multi-object spectrographs. A census of OB associations in this galaxy is also needed, to provide important additional information about the age and environment of the candidate OB stars. Methods. From observations taken with the Wide Field Camera (WFC) at the Isaac Newton Telescope (INT), we have built an astrometric and photometric catalogue of stars in IC 1613. Candidate blue massive stars are preselected by their colors. A friendsof-friends algorithm is developed to find their clustering in the galaxy. While a common physical origin for all the members of the associations cannot be ensured, this is a necessary first step to place candidate OB stars in a population context. Results. We have produced a deep catalogue of targets in IC 1613 that covers a large field of view. To achieve high astrometric accuracy, a new astrometric procedure was developed for the INT-WFC data. We also built a catalogue of OB associations in IC 1613 and found that they concentrate in the central regions, especially in the H ii bubbles. The study of extinction confirms that it is patchy, with local values of color-excess above the foreground value.

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“…On the contrary, the chemical properties of star-forming dwarfs in low-density environments Based on observations acquired from CFHT, CTIO, ESO, OAN-SPM, and SAAO. indicate that gas flows have not played a major role in their evolution (Lee et al 2003;Vaduvescu et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Fundamentals of the dwarf fundamental plane

McCall

Văduvescu

Núñez

et al. 2012

A&A

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Aims. Star-forming dwarfs are studied to elucidate the physical underpinnings of their fundamental plane. Processes controlling dynamics are evaluated, connections between quiescent and bursting dwarfs are examined, and the viability of using structural properties of dwarfs to determine distances is assessed. Methods. Deep surface photometry in K s is presented for 19 star-forming dwarfs. The data are amalgamated with previously published observations to create a sample of 66 galaxies suitable for exploring how global properties and kinematics are connected. Results. It is confirmed that residuals in the Tully-Fisher relation are correlated with surface brightness, but that even after accomodating the surface brightness dependence through the dwarf fundamental plane, residuals in absolute magnitude are far larger than expected from observational errors. Rather, a more fundamental plane is identified which connects the potential to HI line width and surface brightness. Residuals correlate with the axis ratio in a way which can be accommodated by recognizing the galaxies to be oblate spheroids viewed at varying angles. Correction of surface brightnesses to face-on leads to a correlation among the potential, line width, and surface brightness for which residuals are entirely attributable to observational uncertainties. The mean mass-to-light ratio of the diffuse component of the galaxies is constrained to be 0.88±0.20 in K s . Blue compact dwarfs lie in the same plane as dwarf irregulars. The dependence of the potential on line width is less strong than expected for virialized systems, but this may be because surface brightness is acting as a proxy for variations in the mass-to-light ratio from galaxy to galaxy. Altogether, the observations suggest that gas motions are predominantly disordered and isotropic, that they are a consequence of gravity, not turbulence, and that the mass and scale of dark matter haloes scale with the amount and distribution of luminous matter. The tight relationship between the potential and observables offers the promise of determining distances to unresolved star-forming dwarfs to an accuracy comparable to that provided by the Tully-Fisher relation for spirals.

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Uncovering Additional Clues to Galaxy Evolution. I. Dwarf Irregular Galaxies in the Field

Cited by 99 publications

References 135 publications

Massive star formation in Wolf-Rayet galaxies

Massive star formation in Wolf-Rayet galaxies

The young stellar population of IC 1613

Fundamentals of the dwarf fundamental plane

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