The mid-infrared color of NGC 6946

G. Helou; S. Malhotra; C. A. Beichman; H. Dinerstein; D. J. Hollenbach; D. A. Hunter; K. Y. Lo; S. D. Lord; N. Y. Lu; R. H. Rubin; G. J. Stacey; H. A. Thronson; M. W. Werner

The mid-infrared color of NGC 6946

G. Helou, S. Malhotra, C. A. Beichman, H. Dinerstein, D. J. Hollenbach, D. A. Hunter, K. Y. Lo, S. D. Lord, N. Y. Lu, R. H. Rubin, G. J. Stacey, H. A. Thronson, M. W. Werner

Arizona State University

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

We analyze the new mid-infrared maps of NGC 6946 for variations in the color ratio of the 7-to-15μm emission. Our preliminary findings are that this mid-infrared color is remarkably constant between arms and inter-arm regions, and as a function of radius in the disk, excluding the nuclear region. As surface brightness ranges by more than an order of magnitude and the radius runs from about 0.5 to 3 kpc, the color ratio remains constant to about ±20%. Our interpretation is that (1) hard UV radiation from OB stars does not dominate the heating of the grains radiating in the mid-infrared; and (2) that surface brightness variations are driven primarily by surface-filling fraction in the disk, and by radiation intensity increases in starburst environments, such as the nucleus of NGC 6946.

Original language	English (US)
Pages (from-to)	L157-L160
Journal	Astronomy and Astrophysics
Volume	315
Issue number	2
State	Published - Nov 10 1996

Keywords

Galaxies: ISM
Galaxies: individual: NGC 6946
Infrared: galaxies

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Cite this

@article{f528400d65ac4d499428ffd37e97a2be,

title = "The mid-infrared color of NGC 6946",

abstract = "We analyze the new mid-infrared maps of NGC 6946 for variations in the color ratio of the 7-to-15μm emission. Our preliminary findings are that this mid-infrared color is remarkably constant between arms and inter-arm regions, and as a function of radius in the disk, excluding the nuclear region. As surface brightness ranges by more than an order of magnitude and the radius runs from about 0.5 to 3 kpc, the color ratio remains constant to about ±20%. Our interpretation is that (1) hard UV radiation from OB stars does not dominate the heating of the grains radiating in the mid-infrared; and (2) that surface brightness variations are driven primarily by surface-filling fraction in the disk, and by radiation intensity increases in starburst environments, such as the nucleus of NGC 6946.",

keywords = "Galaxies: ISM, Galaxies: individual: NGC 6946, Infrared: galaxies",

author = "G. Helou and S. Malhotra and Beichman, {C. A.} and H. Dinerstein and Hollenbach, {D. J.} and Hunter, {D. A.} and Lo, {K. Y.} and Lord, {S. D.} and Lu, {N. Y.} and Rubin, {R. H.} and Stacey, {G. J.} and Thronson, {H. A.} and Werner, {M. W.}",

year = "1996",

month = nov,

day = "10",

language = "English (US)",

volume = "315",

pages = "L157--L160",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

number = "2",

}

TY - JOUR

T1 - The mid-infrared color of NGC 6946

AU - Helou, G.

AU - Malhotra, S.

AU - Beichman, C. A.

AU - Dinerstein, H.

AU - Hollenbach, D. J.

AU - Hunter, D. A.

AU - Lo, K. Y.

AU - Lord, S. D.

AU - Lu, N. Y.

AU - Rubin, R. H.

AU - Stacey, G. J.

AU - Thronson, H. A.

AU - Werner, M. W.

PY - 1996/11/10

Y1 - 1996/11/10

N2 - We analyze the new mid-infrared maps of NGC 6946 for variations in the color ratio of the 7-to-15μm emission. Our preliminary findings are that this mid-infrared color is remarkably constant between arms and inter-arm regions, and as a function of radius in the disk, excluding the nuclear region. As surface brightness ranges by more than an order of magnitude and the radius runs from about 0.5 to 3 kpc, the color ratio remains constant to about ±20%. Our interpretation is that (1) hard UV radiation from OB stars does not dominate the heating of the grains radiating in the mid-infrared; and (2) that surface brightness variations are driven primarily by surface-filling fraction in the disk, and by radiation intensity increases in starburst environments, such as the nucleus of NGC 6946.

AB - We analyze the new mid-infrared maps of NGC 6946 for variations in the color ratio of the 7-to-15μm emission. Our preliminary findings are that this mid-infrared color is remarkably constant between arms and inter-arm regions, and as a function of radius in the disk, excluding the nuclear region. As surface brightness ranges by more than an order of magnitude and the radius runs from about 0.5 to 3 kpc, the color ratio remains constant to about ±20%. Our interpretation is that (1) hard UV radiation from OB stars does not dominate the heating of the grains radiating in the mid-infrared; and (2) that surface brightness variations are driven primarily by surface-filling fraction in the disk, and by radiation intensity increases in starburst environments, such as the nucleus of NGC 6946.

KW - Galaxies: ISM

KW - Galaxies: individual: NGC 6946

KW - Infrared: galaxies

UR - http://www.scopus.com/inward/record.url?scp=0009180985&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0009180985&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0009180985

SN - 0004-6361

VL - 315

SP - L157-L160

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

IS - 2

ER -

The mid-infrared color of NGC 6946

Abstract

Keywords

ASJC Scopus subject areas

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