Distribution of star-forming complexes in dwarf irregular galaxies

Parodi, Bernhard R.; Binggeli, B.

doi:10.1051/0004-6361:20021587

Cited by 28 publications

(45 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Their radial distribution seems to manifest a double peak as already observed by Parodi & Binggeli (2003). This could be an indication of a privileged radial distance of strong star formation regions, possibly induced by shearing due to differential rotation in the outer part of the disk.…”

Section: Radial Distribution Of Lumpssupporting

confidence: 67%

Automated morphological classification of galaxies using wavelet transform

Cuisinier

Rabaça

2009

Proc. IAU

View full text Add to dashboard Cite

Abstract. The wavelet transform acts to segregate objects in function of their size. We apply this method on images of galaxies to decompose them into coefficients representing only objects of the same size. The total fluxes of the wavelet coefficients describe the cumulative power spectrum of spatial frequencies. Based on this spectrum, we propose a new parameter to quantify the galaxy texture. As expected, it remains small and quite invariant for early-type galaxies, while it covers a large range and takes larger values for late-type galaxies. Combined with a second parameter, our determination of the texture is able to successfully separate galaxy types. By thresholding the wavelet coefficients, we detect luminous lumps. In irregular galaxies, their radial distribution seems to show a double peak. This could be the trace of a privileged radial distance of strong star formation regions.Keywords. galaxies: fundamental parameters (morphology, classification), galaxies: structure, techniques: image processing, methods: data analysis The wavelet transformThe wavelet transform projects an image onto a basis of finite support functions, whose spatial scales vary. Wavelets are families of functions that integrate to zero and are produced by scaling and translating a single function, called the mother wavelet.As the wavelet's support is finite in space, it is not sufficient to project the image onto a unique function. We must create a set of translating functions by frequency. Consequently, instead of obtaining a scalar as coefficient, we get an image; and this for each spatial frequency. There would be many redundancies if we would compute the coefficient for all spatial units. To avoid that, the projection is performed only onto wavelets whose spatial frequencies l, expressed in pixels, are powers of 2: l = 2 s , where s = 1, 2, 3, ..., n determines the scale.Thus, the wavelet transform yields a set of images, one per scale: the wavelet coefficients. These are composed of objects with characteristic sizes, without losing their locations, and are therefore representations of the structure or texture of the image. The sum of all coefficients recovers the original image.In our case, the mother wavelet is a B-spline function.

show abstract

Section: Radial Distribution Of Lumpssupporting

confidence: 67%

Automated morphological classification of galaxies using wavelet transform

Cuisinier

Rabaça

2009

Proc. IAU

View full text Add to dashboard Cite

show abstract

“…Old stellar populations should be diffuse and less concentrated than young populations (Parodi & Binggeli 2003).…”

Section: Approachmentioning

confidence: 99%

“…The effect will obviously be most pronounced in the long-wavelength bandpasses, but will also affect the short-wavelength bands as a portion of the output spectrum of old, red stars is also in these bluer bands. Parodi & Binggeli (2003) constrains the relation between the SFR and B-band scale lengths for nearby dIrrs to r 0; sfr % (0:86 AE 0:06)r 0; B . As this is a local constraint it must be compared to dIrrs with somewhat lower SFRs, and thus we need to lower the SFR of galaxies as indicated in Figure 14.…”

Section: Testsmentioning

confidence: 99%

Using Spatial Distributions to Constrain Progenitors of Supernovae and Gamma‐Ray Bursts

Raskin

Scannapieco

Rhoads

et al. 2008

Astrophysical Journal

View full text Add to dashboard Cite

We carry out a comprehensive theoretical examination of the relationship between the spatial distribution of optical transients and the properties of their progenitor stars. By constructing analytic models of star-forming galaxies and the evolution of stellar populations within them, we are able to place constraints on candidate progenitors for core-collapse supernovae (SNe), long-duration gamma-ray bursts, and SNe Ia. In particular, we first construct models of spiral galaxies that reproduce observations of core-collapse SNe, and we use these models to constrain the minimum mass for SNe Ic progenitors to %25 M . Second, we lay out the parameters of a dwarf irregular galaxy model, which we use to show that the progenitors of long-duration gamma-ray bursts are likely to have masses above %43 M . Finally, we introduce a new method for constraining the timescale associated with SNe Ia and apply it to our spiral galaxy models to show how observations can better be analyzed to discriminate between the leading progenitor models for these objects.

show abstract

“…Otherwise, if the star sample is representative of a population born from various clouds and/or with different star formation histories, then the fractal dimension will represent the gas distribution at different spatial or temporal scales according to a multiscale structure of the ISM (Chappell & Scalo 2001). At a galactic level, the fractal dimension of the distribution of stars and /or star-forming regions exhibits a very wide range of values, but until now no correlation has been clearly found between fractal patterns at the galactic level and other galactic properties (Odekon 2006;Feitzinger & Galinski 1987;Parodi & Binggeli 2003). There are, however, some suggestions that the fractal dimension of the distribution of stars and star-forming sites increases with time after the star formation process (de la Fuente Marcos & de la Fuente Marcos 2006a, 2006cOdekon 2006;Schmeja & Klessen 2006), probably due to the action of some physical mechanisms which tend to reorganize/destroy the original structure.…”

Section: The Fractal Dimension Of the Gould Beltmentioning

confidence: 99%

The Nature of the Gould Belt from a Fractal Analysis of Its Stellar Population

Sánchez

Alfaro

Elías

et al. 2007

ApJ

View full text Add to dashboard Cite

The Gould Belt (GB) is a system of gas and young, bright stars distributed along a plane that is inclined with respect to the main plane of the Milky Way. Observational evidence suggests that the GB is our closest star formation complex, but its true nature and origin remain rather controversial. In this work we analyze the fractal structure of the stellar component of the GB. In order to do this, we tailor and apply an algorithm that estimates the fractal dimension in a precise and accurate way, avoiding both boundary and smallYdata set problems. We find that early OB stars (of spectral types earlier than B4) in the GB have a fractal dimension very similar to that of the gas clouds in our Galaxy. On the contrary, stars in the GB of later spectral types show a larger fractal dimension, similar to that found for OB stars of both age groups in the local Galactic disk (LGD). This result seems to indicate that while the younger OB stars in the GB preserve the memory of the spatial structure of the cloud where they were born, older stars are distributed following a similar morphology as that found for the LGD stars. The possible causes for these differences are discussed.

show abstract

Distribution of star-forming complexes in dwarf irregular galaxies

Cited by 28 publications

References 51 publications

Automated morphological classification of galaxies using wavelet transform

Automated morphological classification of galaxies using wavelet transform

Using Spatial Distributions to Constrain Progenitors of Supernovae and Gamma‐Ray Bursts

The Nature of the Gould Belt from a Fractal Analysis of Its Stellar Population

Contact Info

Product

Resources

About