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Jansen, Wolfgang; Böhmer, Jürgen; Kappus, B.; Beiter, T.; Breitinger, B.; Hock, C. W.

doi:10.1023/a:1017093410395

Cited by 19 publications

(11 citation statements)

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“…The optical fluxes were corrected for internal dust using a relationship between Hα dust attenuation derived from Balmer line ratios and R band absolute magnitude prior to internal dust correction, M ′ R , found and presented by Helmboldt et al (2004) using data from the Nearby Field Galaxy Survey (Jansen 2000;Jansen et al 2000). The R band internal dust attenuation, in magnitudes was taken to be half that of Hα to account for "differential" dust absorption: emission lines are more effected by dust than the stellar continuum (Fanelli et al 1988;Calzetti, Kinney & Storchi-Bergman 1994), presumably because high-mass star formation is more highly correlated with dust than the general field star population.…”

Section: Correction For Internal Dust Absorptionmentioning

confidence: 99%

Evidence for a Nonuniform Initial Mass Function in the Local Universe

Meurer

Wong

Kim

et al. 2009

ApJ

267

361

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Many of the results in modern astrophysics rest on the notion that the Initial Mass Function (IMF) is universal. Our observations of a sample of H I selected galaxies in the light of Hα and the far-ultraviolet (FUV) challenge this result. The extinction corrected flux ratio F Hα / f FUV from these two tracers of star formation shows strong correlations with the surface-brightness in Hα and the R band: Low Surface Brightness (LSB) galaxies have lower F Hα / f FUV ratios compared to High Surface Brightness (HSB) galaxies as well as compared to expectations from equilibrium models of constant star formation rate (SFR) using commonly favored IMF parameters. Weaker but significant correlations of F Hα / f FUV with luminosity, rotational velocity and dynamical mass are found as well as a systematic trend with morphology. The correlated variations of F Hα / f FUV with other global parameters are thus part of the larger family of galaxy scaling relations. The F Hα / f FUV correlations can not be due to residual extinction correction errors, while systematic variations in the star formation history can not explain the trends with both Hα and R surface brightness nor with other global properties. The possibility that LSB galaxies have a higher escape fraction of ionizing photons seems inconsistent with their high gas fraction, and observations of color-magnitude diagrams of a few systems which indicate a real deficit of O stars. The most plausible explanation for the correlations is the systematic variations of the upper mass limit M u and/or the slope γ which define the upper end of the IMF. We outline a scenario of pressure driving the correlations by setting the efficiency of the formation of the dense star clusters where the highest mass stars preferentially form. Our results imply that the star formation rate measured in a galaxy is highly sensitive to the tracer used in the measurement. A non-universal IMF would also call into question interpretation of metal abundance patterns in dwarf galaxies as well star formation histories derived from color magnitude diagrams.

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Section: Correction For Internal Dust Absorptionmentioning

confidence: 99%

Evidence for a Nonuniform Initial Mass Function in the Local Universe

Meurer

Wong

Kim

et al. 2009

ApJ

267

361

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“…The solid and broken curves are the demarcation between HII regions and AGN by Kewley et al (2001) and Kauffmann et al (2003), respectively. Filled dots represent nearby field galaxies Jansen et al (2000), and open dots represent blue compact galaxies from Kong et al (2002). The contour shows the distribution of SDSS galaxies in the MPA-JHU DR7 release of spectrum measurements.…”

Section: Two Of the Regions (Har-34) Exist Out Of Hi Distributionmentioning

confidence: 99%

Multi-Wavelength Studies of Spectacular Ram-Pressure Stripping of a Galaxy. Ii. Star Formation in the Tail

Yagi¹,

Gu²,

Fujita³

et al. 2013

ApJ

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With multiband photometric data in public archives, we detected four intracluster star-forming regions in the Virgo cluster. Two of them were at a projected distance of 35 kpc away from NGC 4388, and the other two were 66 kpc away. Our new spectroscopic observation revealed that their recession velocities were comparable to the ram-pressure-stripped tail of NGC 4388 and confirmed their association. The stellar mass of the star-forming regions ranged from 10 4 -10 4.5 M except for that of the faintest one which would be < 10 3 M . The metallicity was comparable to the solar abundance, and the age of the stars was ∼ 10 6.8 years. Their young stellar age meant that the star formation should have started after the gas was stripped from NGC 4388. This implied in situ condensation of the stripped gas. We also found that two star-forming regions lay near the leading edge of a filamentary dark cloud. The extinction of the filament was smaller than that derived from the Balmer decrement of the star-forming regions. It implied that the dust in the filament would be locally dense around the star-forming regions.

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“…During the early phases of our study our sample also included the Nearby Field Galaxy Survey(Jansen et al 2000). However after the sample was vetted for minimum signal/noise and matching IR data only a handful of galaxies remained.…”

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confidence: 99%

DUST-CORRECTED STAR FORMATION RATES OF GALAXIES. I. COMBINATIONS OF Hα AND INFRARED TRACERS

Kennicutt

Hao

Calzetti

et al. 2009

ApJ

575

829

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We combine Hα emission-line and infrared continuum measurements of two samples of nearby galaxies to derive dust attenuation-corrected star formation rates (SFRs). We use a simple energy balance based method that has been applied previously to HII regions in the Spitzer Infrared Nearby Galaxies Survey (SINGS), and extend the methodology to integrated measurements of galaxies. We find that our composite Hα + IR based SFRs are in excellent agreement with attenuation-corrected SFRs derived from integrated spectrophotometry, over the full range of SFRs (0.01 -80 M ⊙ yr −1 ) and attenuations (0 -2.5 mag) studied. We find that the combination of Hα and total infrared luminosities provides the most robust SFR measurements, but combinations of Hα measurements with monochromatic luminosities at 24 µm and 8 µm perform nearly as well. The calibrations differ significantly from those obtained for HII regions (Calzetti et al. 2007), with the difference attributable to a more evolved population of stars heating the dust. Our results are consistent with a significant component of diffuse dust (the 'IR cirrus' component) that is heated by a non-star-forming -2population. The same methodology can be applied to [O II]λ3727 emissionline measurements, and the radio continuum fluxes of galaxies can be applied in place of IR fluxes when the latter are not available. We assess the precision and systematic reliability of all of these composite methods.-4 -The advent of large sets of multi-wavelength observations of nearby galaxies now provides us with the opportunity to derive attenuation-corrected Hα and UV continuum luminosities of galaxies by combining these fluxes with various components of the IR emission. Moreover the availability of integrated optical spectra (and in some cases Pa α maps) of the same galaxies allows us to derive additional attenuation estimates, and test the precision and systematic reliability of the respective attenuation-corrected SFR measurements.The Spitzer Infrared Nearby Galaxies Survey (SINGS; Kennicutt et al. 2003) offers an ideal dataset for testing and calibrating such multi-wavelength SFR estimators. The survey includes imaging of a diverse sample of 75 galaxies within 30 Mpc, with wavelength coverage extending from the UV to the radio, including ultraviolet imaging at 150 and 230 nm, Hα, and 7 infrared wavelengths over 3.6 -160 µm. In addition, drift-scanned spectra over the wavelength range 3600 -6900Å are available, which complement matching infrared spectra over the range 10 -40 µm. We first applied these data to calibrate and test the combined use of Hα and 24 µm infrared fluxes of individual HII regions to derive attenuation-corrected emission-line fluxes (Calzetti et al. 2007, hereafter denoted C07;Kennicutt et al. 2007;Prescott et al. 2007). These studies revealed that the Spitzer 24 µm sources were highly correlated in position and flux with those of optical HII region counterparts. Kennicutt et al. (2007) and C07 found that the ratio of 24 µm to Hα fluxes yielded attenuation-corrected Hα lum...

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Cited by 19 publications

References 0 publications

Evidence for a Nonuniform Initial Mass Function in the Local Universe

Evidence for a Nonuniform Initial Mass Function in the Local Universe

Multi-Wavelength Studies of Spectacular Ram-Pressure Stripping of a Galaxy. Ii. Star Formation in the Tail

DUST-CORRECTED STAR FORMATION RATES OF GALAXIES. I. COMBINATIONS OF Hα AND INFRARED TRACERS

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