Ultraviolet-optical pixel maps of face-on spiral galaxies

Clues for dynamics and star formation histories

Paul B. Eskridge, Jay A. Frogel, Violet A. Taylor, Rogier Windhorst, Stephen C. Odewahn, Claudia A T C Chiarenza, Christopher J. Conselice, Richard De Grijs, Lynn D. Matthews, Robert W. O'Connell, John S. Gallagher

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Ultraviolet and optical images of the face-on spiral galaxies NGC 6753 and NGC 6782 reveal regions of strong ongoing star formation that are associated with structures traced by the old stellar populations. We use these images to construct NUV-(NUV-I814) pixel color-magnitude diagrams (pCMDs) that reveal plumes of pixels with strongly varying near-ultraviolet (NUV) surface brightness and nearly constant I814 surface brightness. The plumes correspond to sharply bounded radial ranges, with (NUV-I814) at a given NUV surface brightness being bluer at larger radii. The plumes are parallel to both the reddening vector and simple model mixtures of young and old populations, thus neither reddening nor the fraction of the young population can produce the observed separation between the plumes. The images and radial surface brightness and color plots indicate that the separate plumes are caused by sharp declines in the surface densities of the old populations at radii corresponding to disk resonances. The maximum surface brightness of the NUV light remains essentially constant with radius, while the maximum I814 surface brightness declines sharply with radius. A mid-ultraviolet (MUV) image of NGC 6782 shows emission from the nuclear ring. The distribution of points in an (MUV-NUV)-(NUV-I814) pixel color-color diagram is broadly consistent with the simple mixture model but shows a residual trend that the bluest pixels in (MUV-NUV) are the reddest pixels in (NUV-I814). This may be due to a combination of red continuum from late-type supergiants and [S III] emission lines associated with H II regions in active star-forming regions. We have shown that pixel mapping is a powerful tool for studying the distribution and strength of ongoing star formation in galaxies. Deep, multicolor imaging can extend this to studies of extinction and the ages and metallicities of composite stellar populations in nearby galaxies.

Original languageEnglish (US)
Pages (from-to)923-938
Number of pages16
JournalAstrophysical Journal
Volume586
Issue number2 I
DOIs
StatePublished - Apr 1 2003

Fingerprint

spiral galaxies
star formation
pixel
pixels
histories
brightness
plumes
plume
history
radii
diagram
galaxies
color-color diagram
young population
color-magnitude diagram
H II regions
ultraviolet radiation
metallicity
extinction
plots

Keywords

  • Galaxies: individual (NGC 6753, NGC 6782)
  • Galaxies: photometry
  • Galaxies: spiral
  • Galaxies: structure
  • Ultraviolet: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Eskridge, P. B., Frogel, J. A., Taylor, V. A., Windhorst, R., Odewahn, S. C., Chiarenza, C. A. T. C., ... Gallagher, J. S. (2003). Ultraviolet-optical pixel maps of face-on spiral galaxies: Clues for dynamics and star formation histories. Astrophysical Journal, 586(2 I), 923-938. https://doi.org/10.1086/367820

Ultraviolet-optical pixel maps of face-on spiral galaxies : Clues for dynamics and star formation histories. / Eskridge, Paul B.; Frogel, Jay A.; Taylor, Violet A.; Windhorst, Rogier; Odewahn, Stephen C.; Chiarenza, Claudia A T C; Conselice, Christopher J.; De Grijs, Richard; Matthews, Lynn D.; O'Connell, Robert W.; Gallagher, John S.

In: Astrophysical Journal, Vol. 586, No. 2 I, 01.04.2003, p. 923-938.

Research output: Contribution to journalArticle

Eskridge, PB, Frogel, JA, Taylor, VA, Windhorst, R, Odewahn, SC, Chiarenza, CATC, Conselice, CJ, De Grijs, R, Matthews, LD, O'Connell, RW & Gallagher, JS 2003, 'Ultraviolet-optical pixel maps of face-on spiral galaxies: Clues for dynamics and star formation histories', Astrophysical Journal, vol. 586, no. 2 I, pp. 923-938. https://doi.org/10.1086/367820
Eskridge, Paul B. ; Frogel, Jay A. ; Taylor, Violet A. ; Windhorst, Rogier ; Odewahn, Stephen C. ; Chiarenza, Claudia A T C ; Conselice, Christopher J. ; De Grijs, Richard ; Matthews, Lynn D. ; O'Connell, Robert W. ; Gallagher, John S. / Ultraviolet-optical pixel maps of face-on spiral galaxies : Clues for dynamics and star formation histories. In: Astrophysical Journal. 2003 ; Vol. 586, No. 2 I. pp. 923-938.
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AU - Windhorst, Rogier

AU - Odewahn, Stephen C.

AU - Chiarenza, Claudia A T C

AU - Conselice, Christopher J.

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