Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331

David A. Thilker, Samuel Boissier, Luciana Bianchi, Daniela Calzetti, Alessandro Boselli, Daniel A. Dale, Mark Seibert, Robert Braun, Denis Burgarella, Armando Gil De Paz, George Helou, Fabian Walter, R. C. Kennicutt, Barry F. Madore, D. Christopher Martin, Tom A. Barlow, Karl Forster, Peter G. Friedman, Patrick Morrissey, Susan G. NeffDavid Schiminovich, Todd Small, Ted K. Wyder, José Donas, Timothy M. Heckman, Young Wook Lee, Bruno Milliard, R. Michael Rich, Alex S. Szalay, Barry Y. Welsh, Sukyoung K. Yi

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Abstract

We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850 μm is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b8) that is highest in the outer part of the disk, even though the local star formation intensity peaks in the ring. Bolometric luminosity and UV attenuation are correlated in substructures on 0.4 kpc scales, with a relationship similar to that established for starburst galaxies. The distribution of substructures in L(IR)/L(FUV), Lλ(FUV)/Lλ(NUV) space suggests that the majority of the disk is best characterized by Milky Way-type dust, with the exception of sources in the star-forming ring. As found by Calzetti et al. in M51, the observed 8 and 24 μm luminosity for substructures in NGC 7331 are correlated, showing a decline in Lv(8 μm)/Lv(24 μm) with increasing luminosity. We demonstrate the dependence of Lv(8 μm)/Lv(24 μm) on the local extinction-corrected Hα surface brightness (hence current ΣSFR). A power law of slope 1.64 (1.87) accurately describes the Schmidt-law relation versus ΣH2gas) for molecular-dominated environments. The same locations show no correlation between ΣSFR and ΣHI. For atomic-dominated regions above an apparent local star formation threshold, we found a trend for increasing ΣSFR at higher ΣHI, although the Schmidt-law correlation with molecular-only surface density persists in areas dominated by atomic gas.

Original languageEnglish
Pages (from-to)572-596
Number of pages25
JournalAstrophysical Journal, Supplement Series
Volume173
Issue number2
DOIs
Publication statusPublished - 2007 Dec 1

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substructures
star formation
dust
luminosity
rings
brightness
extinction
local extinction
gas
stars
starburst galaxies
monatomic gases
power law
imagery
tracing
profiles
photometry
attenuation
signatures
slopes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Thilker, D. A., Boissier, S., Bianchi, L., Calzetti, D., Boselli, A., Dale, D. A., ... Yi, S. K. (2007). Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331. Astrophysical Journal, Supplement Series, 173(2), 572-596. https://doi.org/10.1086/516646
Thilker, David A. ; Boissier, Samuel ; Bianchi, Luciana ; Calzetti, Daniela ; Boselli, Alessandro ; Dale, Daniel A. ; Seibert, Mark ; Braun, Robert ; Burgarella, Denis ; De Paz, Armando Gil ; Helou, George ; Walter, Fabian ; Kennicutt, R. C. ; Madore, Barry F. ; Martin, D. Christopher ; Barlow, Tom A. ; Forster, Karl ; Friedman, Peter G. ; Morrissey, Patrick ; Neff, Susan G. ; Schiminovich, David ; Small, Todd ; Wyder, Ted K. ; Donas, José ; Heckman, Timothy M. ; Lee, Young Wook ; Milliard, Bruno ; Rich, R. Michael ; Szalay, Alex S. ; Welsh, Barry Y. ; Yi, Sukyoung K. / Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331. In: Astrophysical Journal, Supplement Series. 2007 ; Vol. 173, No. 2. pp. 572-596.
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abstract = "We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850 μm is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b8) that is highest in the outer part of the disk, even though the local star formation intensity peaks in the ring. Bolometric luminosity and UV attenuation are correlated in substructures on 0.4 kpc scales, with a relationship similar to that established for starburst galaxies. The distribution of substructures in L(IR)/L(FUV), Lλ(FUV)/Lλ(NUV) space suggests that the majority of the disk is best characterized by Milky Way-type dust, with the exception of sources in the star-forming ring. As found by Calzetti et al. in M51, the observed 8 and 24 μm luminosity for substructures in NGC 7331 are correlated, showing a decline in Lv(8 μm)/Lv(24 μm) with increasing luminosity. We demonstrate the dependence of Lv(8 μm)/Lv(24 μm) on the local extinction-corrected Hα surface brightness (hence current ΣSFR). A power law of slope 1.64 (1.87) accurately describes the Schmidt-law relation versus ΣH2 (Σgas) for molecular-dominated environments. The same locations show no correlation between ΣSFR and ΣHI. For atomic-dominated regions above an apparent local star formation threshold, we found a trend for increasing ΣSFR at higher ΣHI, although the Schmidt-law correlation with molecular-only surface density persists in areas dominated by atomic gas.",
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Thilker, DA, Boissier, S, Bianchi, L, Calzetti, D, Boselli, A, Dale, DA, Seibert, M, Braun, R, Burgarella, D, De Paz, AG, Helou, G, Walter, F, Kennicutt, RC, Madore, BF, Martin, DC, Barlow, TA, Forster, K, Friedman, PG, Morrissey, P, Neff, SG, Schiminovich, D, Small, T, Wyder, TK, Donas, J, Heckman, TM, Lee, YW, Milliard, B, Rich, RM, Szalay, AS, Welsh, BY & Yi, SK 2007, 'Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331', Astrophysical Journal, Supplement Series, vol. 173, no. 2, pp. 572-596. https://doi.org/10.1086/516646

Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331. / Thilker, David A.; Boissier, Samuel; Bianchi, Luciana; Calzetti, Daniela; Boselli, Alessandro; Dale, Daniel A.; Seibert, Mark; Braun, Robert; Burgarella, Denis; De Paz, Armando Gil; Helou, George; Walter, Fabian; Kennicutt, R. C.; Madore, Barry F.; Martin, D. Christopher; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Small, Todd; Wyder, Ted K.; Donas, José; Heckman, Timothy M.; Lee, Young Wook; Milliard, Bruno; Rich, R. Michael; Szalay, Alex S.; Welsh, Barry Y.; Yi, Sukyoung K.

In: Astrophysical Journal, Supplement Series, Vol. 173, No. 2, 01.12.2007, p. 572-596.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331

AU - Thilker, David A.

AU - Boissier, Samuel

AU - Bianchi, Luciana

AU - Calzetti, Daniela

AU - Boselli, Alessandro

AU - Dale, Daniel A.

AU - Seibert, Mark

AU - Braun, Robert

AU - Burgarella, Denis

AU - De Paz, Armando Gil

AU - Helou, George

AU - Walter, Fabian

AU - Kennicutt, R. C.

AU - Madore, Barry F.

AU - Martin, D. Christopher

AU - Barlow, Tom A.

AU - Forster, Karl

AU - Friedman, Peter G.

AU - Morrissey, Patrick

AU - Neff, Susan G.

AU - Schiminovich, David

AU - Small, Todd

AU - Wyder, Ted K.

AU - Donas, José

AU - Heckman, Timothy M.

AU - Lee, Young Wook

AU - Milliard, Bruno

AU - Rich, R. Michael

AU - Szalay, Alex S.

AU - Welsh, Barry Y.

AU - Yi, Sukyoung K.

PY - 2007/12/1

Y1 - 2007/12/1

N2 - We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850 μm is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b8) that is highest in the outer part of the disk, even though the local star formation intensity peaks in the ring. Bolometric luminosity and UV attenuation are correlated in substructures on 0.4 kpc scales, with a relationship similar to that established for starburst galaxies. The distribution of substructures in L(IR)/L(FUV), Lλ(FUV)/Lλ(NUV) space suggests that the majority of the disk is best characterized by Milky Way-type dust, with the exception of sources in the star-forming ring. As found by Calzetti et al. in M51, the observed 8 and 24 μm luminosity for substructures in NGC 7331 are correlated, showing a decline in Lv(8 μm)/Lv(24 μm) with increasing luminosity. We demonstrate the dependence of Lv(8 μm)/Lv(24 μm) on the local extinction-corrected Hα surface brightness (hence current ΣSFR). A power law of slope 1.64 (1.87) accurately describes the Schmidt-law relation versus ΣH2 (Σgas) for molecular-dominated environments. The same locations show no correlation between ΣSFR and ΣHI. For atomic-dominated regions above an apparent local star formation threshold, we found a trend for increasing ΣSFR at higher ΣHI, although the Schmidt-law correlation with molecular-only surface density persists in areas dominated by atomic gas.

AB - We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850 μm is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b8) that is highest in the outer part of the disk, even though the local star formation intensity peaks in the ring. Bolometric luminosity and UV attenuation are correlated in substructures on 0.4 kpc scales, with a relationship similar to that established for starburst galaxies. The distribution of substructures in L(IR)/L(FUV), Lλ(FUV)/Lλ(NUV) space suggests that the majority of the disk is best characterized by Milky Way-type dust, with the exception of sources in the star-forming ring. As found by Calzetti et al. in M51, the observed 8 and 24 μm luminosity for substructures in NGC 7331 are correlated, showing a decline in Lv(8 μm)/Lv(24 μm) with increasing luminosity. We demonstrate the dependence of Lv(8 μm)/Lv(24 μm) on the local extinction-corrected Hα surface brightness (hence current ΣSFR). A power law of slope 1.64 (1.87) accurately describes the Schmidt-law relation versus ΣH2 (Σgas) for molecular-dominated environments. The same locations show no correlation between ΣSFR and ΣHI. For atomic-dominated regions above an apparent local star formation threshold, we found a trend for increasing ΣSFR at higher ΣHI, although the Schmidt-law correlation with molecular-only surface density persists in areas dominated by atomic gas.

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Thilker DA, Boissier S, Bianchi L, Calzetti D, Boselli A, Dale DA et al. Ultraviolet and infrared diagnostics of star formation and dust in NGC 7331. Astrophysical Journal, Supplement Series. 2007 Dec 1;173(2):572-596. https://doi.org/10.1086/516646