A Spectral Classification of Galaxies

Morgan, W. W.; Mayall, N. U.

doi:10.1086/127075

Cited by 140 publications

(87 citation statements)

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“…In more distant galaxies integrated spectra can be used to identify regions of star formation (e.g. Morgan and Mayall 1957, Morgan 1958, Faber 1972, O'Connell 1976, Williams 1976, Turnrose 1976, Pritchet 1977, Whitford 1977. At nearly any distance, broad-band colors can be used to discern population characteristics of the underlying stellar population (e.g.…”

Section: Single Stars Integrated Spectra and Colorsmentioning

confidence: 99%

“…Morgan and Mayall 1957, Morgan 1958, Morgan and Osterbrock 1969, Faber 1972, Spinrad and Peimbert 1975, Whitford 1975, Williams 1976, O'Connell 1976, Strom et al 1976, Pritchet 1977, Frogel et al 1978, Aaronson 1978, Strom and Strom 1978a quite clearly indicate that no stars have been formed in a long time (e.g. Gunn 1976a, b, Tinsley 1978).…”

Section: Elliptical Galaxiesmentioning

confidence: 99%

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Star Formation in the Nuclei of Normal Galaxies

Biermann

1980

Highlights astron.

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For the purpose of this talk, I define all those galaxies as normal whose nuclear regions are not known to be dominated by a compact source. Thus I will exclude N galaxies, Seyfert galaxies and radio galaxies, but include galaxies like M81 and M82 which have weak compact nuclei. My review is organized in three parts, (i) tracers of star formation, (ii) star formation in the nuclear regions of observed galaxies, and (iii) the theoretical attempts to interpret the observational material.

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Section: Single Stars Integrated Spectra and Colorsmentioning

confidence: 99%

Section: Elliptical Galaxiesmentioning

confidence: 99%

Star Formation in the Nuclei of Normal Galaxies

Biermann

1980

Highlights astron.

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“…The first attempts to automatically classify galaxies were made by Morgan & Mayall (1957) and Morgan & Osterbrock (1969), and were followed by the work of Kormendy & Bender (1996), who tried to classify elliptical galaxies by their internal structures. Other studies used central concentration as an indicator that can determine the position of a galaxy on the Hubble sequence (Doi et al 1993;Brinchmann et al 1998;Shimasaku et al 2001), or the central concentration and asymmetry of galaxian light (Abraham et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Shamir

2011

ApJ

149

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We describe Ganalyzer, a model-based tool that can automatically analyze and classify galaxy images. Ganalyzer works by separating the galaxy pixels from the background pixels, finding the center and radius of the galaxy, generating the radial intensity plot, and then computing the slopes of the peaks detected in the radial intensity plot to measure the spirality of the galaxy and determine its morphological class. Unlike algorithms that are based on machine learning, Ganalyzer is based on measuring the spirality of the galaxy, a task that is difficult to perform manually, and in many cases can provide a more accurate analysis compared to manual observation. Ganalyzer is simple to use, and can be easily embedded into other image analysis applications. Another advantage is its speed, which allows it to analyze ∼10,000,000 galaxy images in five days using a standard modern desktop computer. These capabilities can make Ganalyzer a useful tool in analyzing large data sets of galaxy images collected by autonomous sky surveys such as SDSS, LSST, or DES. The software is available for free download at

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“…Techniques have been devised to classify galaxies using their spectra only (Morgan & Mayall 1957;Sodré & Cuevas 1994, 1997Connolly et al 1995;Zaritsky et al 1994;Folkes et al 1996;Galaz & de Lapparent 1998;Sodré & Stasińska 1999). It has been shown that the results correlate rather well with the galaxy morphological types.…”

Section: Introductionmentioning

confidence: 99%

Global emission line trends in spiral galaxies: The reddening and metallicity sequences

Stasińska

Sodré

2001

A&A

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Abstract.We have explored the emission line trends in the integrated spectra of normal spiral galaxies of the Nearby Field Galaxy Survey (Jansen et al. 2000a, b), in order to investigate the relationships between dust extinction, metallicity and some macroscopic properties of spiral galaxies. We found a very strong correlation between the Hβ and Hα equivalent widths, implying that the difference between the extinction of the stellar and the nebular light depends only on the intrinsic colours of the galaxies, being larger for redder galaxies. ii] λ6584/Hα, the latter having the advantage of being independent of reddening and being applicable also for galaxies with weak emission lines. With these indicators, we find that the nebular extinction as derived from the Balmer decrement strongly correlates with the effective metallicity of the emission line regions. The overall metallicity of the emission line regions is much better correlated with galaxy colours than with morphological types. A Principal Component Analysis on a 7-D parameter space showed that the variance is produced, in first place, by the metallicity and parameters linked to the stellar populations, and, in second place, by the surface brightness, which is linked to the dynamical history of the galaxies. The absolute magnitude, related to the mass of the galaxy, comes only in third place.

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A Spectral Classification of Galaxies

Cited by 140 publications

References 0 publications

Star Formation in the Nuclei of Normal Galaxies

Star Formation in the Nuclei of Normal Galaxies

Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Global emission line trends in spiral galaxies: The reddening and metallicity sequences

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