Photometric and morphological analysis of UCM galaxies. 
I. Observations and reductions. Morphological
classifications

Vitores, A. G.; Zamorano, J.; Rego, M.; Alonso, O.; Gallego, J.

doi:10.1051/aas:1996178

Cited by 30 publications

(52 citation statements)

References 11 publications

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“…The plot featuring the individual galaxy values shows a large scatter within each galaxy type. Vitores et al (1996a) estimate the typical uncertainty in their adopted morphologies to be about one Hubble type. However, this is unlikely to be the primary cause of the scatter, as inspection of the mean extinctions for each galaxy type reveals that A(Hα) varies little between S0 and Sb type galaxies.…”

Section: The Dependence Of Internal Extinction On Morphologymentioning

confidence: 97%

“…The UCM dataset thus provides galaxy ellipticities (Pérez-González et al 2001), morphologies (Vitores et al 1996a) and E(B − V) colour excesses for a large number of galaxies. These can be used to investigate the dependence of internal extinction on galaxy inclination and morphology, which proved impossible with our Brγ observations.…”

Section: The Ucm Hα Surveymentioning

confidence: 99%

“…Corrections for Galactic extinction can be found in Vitores et al (1996a). These have been determined from the Burstein & Heiles (1982) maps at the Galactic coordinates of each UCM object.…”

Section: The Dependence Of Internal Extinction On Inclinationmentioning

confidence: 99%

“…Vitores et al (1996a) classify each of the UCM galaxies according to the classical Hubble types, as well as including the BCD (Blue Compact Dwarf) type. They define BCDs as galaxies possessing all of the following properties: compact appearance in the direct image, linear size (D 24 ) lower than 10 kpc, luminosity M R > −19, and photometric parameters typical of later Hubble types.…”

Section: The Dependence Of Internal Extinction On Morphologymentioning

confidence: 99%

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The Hα Galaxy Survey

James¹,

Shane²,

Knapen³

et al. 2005

A&A

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Abstract. We study the two main corrections generally applied to narrow-band Hα fluxes from galaxies in order to convert them to star formation rates, namely for [N] contamination and for extinction internal to the galaxy. From an imaging study using carefully chosen narrow-band filters, we find the [N] and Hα emission to be differently distributed. Nuclear measurements are likely to overestimate the contribution of [N] to total narrow-band fluxes. We find that in most star formation regions in galaxy disks the [N] fraction is small or negligible, whereas some galaxies display a diffuse central component which can be dominated by [N] emission. We compare these results with related studies in the literature, and consider astrophysical explanations for variations in the [N]/Hα ratio, including metallicity variations and different excitation mechanisms. We proceed to estimate the extinction towards star formation regions in spiral galaxies, firstly using Brγ/Hα line ratios. We find that extinction values are larger in galaxy nuclei than in disks, that disk extinction values are similar to those derived from optical emission-line studies in the literature, and that there is no evidence for heavily dust-embedded regions emerging in the near-IR, which would be invisible at Hα. The numbers of galaxies and individual regions detected in Brγ are small, however, and we thus exploit optical emission line data from the literature to derive global Hα extinction values as a function of galaxy type and inclination. In this part of our study we find only a moderate dependence on inclination, consistent with broad-band photometric studies, and a large scatter from galaxy to galaxy. Typical extinctions are smaller for late-type dwarfs than for spiral types. Finally, we show that the application of the type-dependent extinction corrections derived here significantly improves the agreement between star formation rates calculated using Hα fluxes and those from far-infrared fluxes as measured by IRAS. This again supports the idea that heavily dust-embedded star formation, which would be underestimated using the Hα technique, is not a dominant contributor to the total star formation rate of most galaxies in the local Universe.

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Section: The Dependence Of Internal Extinction On Morphologymentioning

confidence: 97%

Section: The Ucm Hα Surveymentioning

confidence: 99%

Section: The Dependence Of Internal Extinction On Inclinationmentioning

confidence: 99%

Section: The Dependence Of Internal Extinction On Morphologymentioning

confidence: 99%

See 2 more Smart Citations

The Hα Galaxy Survey

James¹,

Shane²,

Knapen³

et al. 2005

A&A

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show abstract

“…In recent years BCGs have attracted a great deal of interest and have become key in understanding fundamental astrophysical problems. Most of the work carried out has focused on a statistical analysis of BCG samples by means of surface photometry (Papaderos et al 1996;Vitores et al 1996;Doublier et al 1997;Östlin et al 1999;Cairós et al 2001;Gil de Paz et al 2003). The measured broadband colors are strongly affected by interstellar extinction and gaseous emission; therefore, optical broadband photometry alone does not allow us to derive their physical properties accurately.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic study of blue compact galaxies

Kong

2004

A&A

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Abstract. This is the fourth paper in a series studying star formation rates, stellar components, metallicities, and star formation histories of a blue compact galaxy (BCG) sample. Using Hα, [O ]λ3727, infrared (IR), radio (1.4 GHz) luminosities and neutral hydrogen (H ) gas masses, we estimated star formation rates and gas depletion timescales of 72 star-forming BCGs. The star formation rates of the BCGs in our sample span nearly four orders of magnitude, from approximately 10 −2 to 10 2 M yr −1 , with a median star formation rate of about 3 M yr −1 . The typical gas depletion timescale of BCGs is about one billion years. Star formation could be sustained at the current level only on a timescale significantly lower than the age of the universe before their neutral gas reservoir is completely depleted. To assess the possible systematic differences among different star formation rate indicators, we compared the star formation rates derived from Hα, [O ]λ3727, IR, and radio luminosities, and investigated the effects from underlying stellar absorption and dust extinction. We found that subtracting underlying stellar absorption is very important to calculate both dust extinction and star formation rate of galaxies. Otherwise, the intrinsic extinction will be overestimated, the star formation rates derived from [O ]λ3727 and Hα will be underestimated (if the underlying stellar absorption and the internal extinction were not corrected from the observed luminosity) or overestimated (if an overestimated internal extinction were used for extinction correction). After both the underlying stellar absorption and the dust extinction were corrected, a remarkably good correlation emerges among Hα, [O ]λ3727, IR and radio star formation rate indicators. Finally, we find a good correlation between the measured star formation rate and the absolute blue magnitude, metallicity, interstellar extinction of BCGs. Our results indicate that faint, low-mass BCGs have lower star formation rates.

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Stellar Populations in Local Star-Forming Galaxies

Pérez‐González¹,

Zamorano²,

Gallego³

et al. 2003

Highlights of Spanish Astrophysics III

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One of the main issues in today's Astrophysics is how present day galaxies formed and how they have evolved over time. A considerable observational effort is being made to study galaxies from the earliest possible times to the present. One approach to understand how present-day galaxies came into being is to study in detail the properties of local active star-forming galaxies, and in particular their star-formation histories. In this respect, it is important to quantify the relative importance of the current episode of star formation in comparison to the underlying older stellar populations.

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Photometric and morphological analysis of UCM galaxies. I. Observations and reductions. Morphological classifications

Cited by 30 publications

References 11 publications

The Hα Galaxy Survey

The Hα Galaxy Survey

Spectroscopic study of blue compact galaxies

Stellar Populations in Local Star-Forming Galaxies

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