The Anatomy of Star Formation in NGC 300

Hélou, G.; Roussel, H.; Appleton, P. N.; Frayer, David; Stolovy, S.; Storrie-Lombardi, L. J.; Hurt, Robert L.; Lowrance, P.; Makovoz, David; Masci, Frank J.; Surace, J.; Gordon, K. D.; Alonso‐Herrero, A.; Engelbracht, C. W.; Misselt, K. A.; Rieke, G. H.; Rieke, M. J.; Willner, S. P.; Pahre, M. A.; Ashby, M. L. N.; Fazio, G. G.; Smith, H. A.

doi:10.1086/422640

Cited by 272 publications

(300 citation statements)

References 30 publications

(31 reference statements)

Supporting

Mentioning

267

Contrasting

Order By: Relevance

“…We conclude that our measurements are consistent within 1σ and our errors are in general equivalent to or larger than the values derived by Barmby et al (2006) and Gordon et al (2006). We finally subtracted from the 8 μm and the 24 μm maps the stellar continuum, which was assumed to be described by the 3.6 μm map following Helou et al (2004):…”

Section: Irsupporting

confidence: 57%

Properties of M31

Montalto¹,

Seitz²,

Riffeser³

et al. 2009

A&A

View full text Add to dashboard Cite

Aims. Observations acquired by the Spitzer Space Telescope and improvements to theoretical modeling of dust emission properties are used to discuss the distribution of dust and its characteristics in the closest neighbor spiral galaxy M31. These data are then used with GALEX FUV, NUV, and SDSS images to study the age dependence of the dust heating process. Methods. Spitzer IRAC/MIPS maps of M31 were matched together and compared to dust emission models allowing us to constrain the dust mass, the intensity of the mean radiation field, the abundance of polycyclic aromatic hydrocarbon (PAH) particles. The total infrared emission (TIR) was analyzed as a function of UV and optical colors and compared to predictions of models that consider age-dependent dust heating. Results. We demonstrate that cold-dust component emission dominates the infrared spectral energy distribution of M31. The mean intensity of the radiation field heating the dust is low (typically U < 2, where U = 1 is the value in the solar neighborhood). Because of a lack of submillimeter observations, the dust mass (M dust ) is only weakly constrained by the infrared spectrum, but we derived a lower limit of M dust 1.1 × 10 7 M with a best-fit model value of M dust = 7.6 × 10 7 M , in good agreement with expectations from CO and HI measurements. Across the spiral-ring structure of M31, we show that a fraction >3% of the total dust mass is in PAHs. UV and optical colors are correlated with the total infrared to far ultraviolet (TIR/FUV) ratios in ∼670 pc-sized regions over the disk of M31, although deviating from the relationship between infrared excess and ultraviolet spectral slope (referred as IRX-β relationship) for starburst galaxies. In particular, redder regions have lower values of the TIR/FUV ratio for a fixed color. Considering the predictions of models that account for the dust-heating age dependence, we found that in 83% of the regions analyzed across the 10 kpc ring, more than 50% of the energy absorbed by the dust is rediated at λ > 4000 Å and that dust in M31 appears mainly heated by populations a few Gyr old even across the star-forming ring. We also found that the attenuation varies radially peaking close to 10 kpc and decreases more rapidly with radius in the inner regions of M31 than in the outer regions in agreement with previous studies. We finally derived the attenuation map of M31 at 6 /px resolution (∼100 pc/px along the plane of M31). Conclusions.

show abstract

Section: Irsupporting

confidence: 57%

Properties of M31

Montalto¹,

Seitz²,

Riffeser³

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…The absence of bright 8 µm emission in the spiral arms might, partly, be linked to the underestimation of the 24 µm emission and, thus, star formation activity (see later). Alternatively, the improper characterization of the PAH abundance in the RT model (assuming a constant PAH fraction throughout the galaxy), which does not account for the destruction of PAHs exposed to hard radiation fields (e.g., Boselli et al 2004;Helou et al 2004;Calzetti et al 2005;Prescott et al 2007;Bendo et al 2008;Gordon et al 2008), might explain the differences between model and observations.…”

Section: Stellar and Dust Emissionmentioning

confidence: 99%

High-resolution, 3D radiative transfer modeling

Looze

Fritz

Baes

et al. 2014

A&A

114

View full text Add to dashboard Cite

Context. Dust reprocesses about half of the stellar radiation in galaxies. The thermal re-emission by dust of absorbed energy is considered to be driven merely by young stars so is often applied to tracing the star formation rate in galaxies. Recent studies have argued that the old stellar population might be responsible for a non-negligible fraction of the radiative dust heating. Aims. In this work, we aim to analyze the contribution of young ( < ∼ 100 Myr) and old (∼10 Gyr) stellar populations to radiative dust heating processes in the nearby grand-design spiral galaxy M 51 using radiative transfer modeling. High-resolution 3D radiative transfer (RT) models are required to describe the complex morphologies of asymmetric spiral arms and clumpy star-forming regions and to model the propagation of light through a dusty medium. Methods. In this paper, we present a new technique developed to model the radiative transfer effects in nearby face-on galaxies. We construct a high-resolution 3D radiative transfer model with the Monte-Carlo code SKIRT to account for the absorption, scattering, and non-local thermal equilibrium (NLTE) emission of dust in M 51. The 3D distribution of stars is derived from the 2D morphology observed in the IRAC 3.6 µm, GALEX FUV, Hα, and MIPS 24 µm wavebands, assuming an exponential vertical distribution with an appropriate scale height. The dust geometry is constrained through the far-ultraviolet (FUV) attenuation, which is derived from the observed total-infrared-to-far-ultraviolet luminosity ratio. The stellar luminosity, star formation rate, and dust mass have been scaled to reproduce the observed stellar spectral energy distribution (SED), FUV attenuation, and infrared SED. Results. The dust emission derived from RT calculations is consistent with far-infrared and submillimeter observations of M 51, implying that the absorbed stellar energy is balanced by the thermal re-emission of dust. The young stars provide 63% of the energy for heating the dust responsible for the total infrared emission (8−1000 µm), while 37% of the dust emission is governed through heating by the evolved stellar population. In individual wavebands, the contribution from young stars to the dust heating dominates at all infrared wavebands but gradually decreases towards longer infrared and submillimeter wavebands for which the old stellar population becomes a non-negligible source of heating. Upon extrapolation of the results for M 51, we present prescriptions for estimating the contribution of young stars to the global dust heating based on a tight correlation between the dust heating fraction and specific star formation rate.

show abstract

“…Following Helou et al (2004), we subtracted the stellar continuum from the 24 μm surface brightnesses (in MJy sr −1 ) using I ν (24 μm) = I ν (24 μm) − 0.032 I ν (3.6 μm).…”

Section: The Low Star Formation Efficiency In the Bridgementioning

confidence: 99%

A dynamical model for the Taffy galaxies UGC 12914/5

Vollmer¹,

Braine²,

Soida³

2012

A&A

View full text Add to dashboard Cite

The spectacular head-on collision of the two gas-rich galaxies of the Taffy system, UGC 12914/15, gives us a unique opportunity to study the consequences of a direct ISM-ISM collision. To interpret existing multi-wavelength observations, we made dynamical simulations of the Taffy system including a sticky particle component. To compare simulation snapshots to Hi and CO observations, we assume that the molecular fraction of the gas depends on the square root of the gas volume density. For the comparison of our simulations with observations of polarized radio continuum emission, we calculated the evolution of the 3D large-scale magnetic field for our simulations. The induction equations including the time-dependent gas-velocity fields from the dynamical model were solved for this purpose. Our simulations reproduce the stellar distribution of the primary galaxy, UGC 12914, the prominent Hi and CO gas bridge, the offset between the CO and Hi emission in the bridge, the bridge isovelocity vectors parallel to the bridge, the Hi double-line profiles in the bridge region, the large line-widths (∼200 km s −1 ) in the bridge region, the high field strength of the bridge large-scale regular magnetic field, the projected magnetic field vectors parallel to the bridge and the strong total power radio continuum emission from the bridge. The stellar distribution of the secondary model galaxy is more perturbed than observed. The observed distortion of the Hi envelope of the Taffy system is not reproduced by our simulations which use initially symmetric gas disks. The model allows us to define the bridge region in three dimensions. We estimate the total bridge gas mass (Hi, warm and cold H 2 ) to be 5 to 6× 10 9 M , with a molecular fraction M H 2 /M HI of about unity. Despite the enormous mass of molecular gas in the bridge, very little star formation is present, similar to other systems with extraplanar gas and broad CO lines. The structure of the model gas bridge is bimodal: on kpc-scales there is a dense ( 0.01 M pc −3 ) component with a high velocity dispersion >100 km s −1 and a less dense (∼10 −3 M pc −3 ) component with a smaller, but still high, velocity dispersion ∼50 km s −1 . The synchrotron lifetime of relativistic electrons is only long enough to be consistent with the existence of the radio continuum bridge for the less dense component. On the other hand, only the high-density gas undergoes a high enough mechanical energy input to produce the observed strong emission of warm H 2 . We propose that, despite the high local gas densities, this high input of mechanical energy drives strong turbulence and quenches star formation in the bridge gas except for the giant Hii region near UGC 12915. Our model suggests that we observe this galaxy head-on collision near the time of maximum CO and H 2 emission.

show abstract

The Anatomy of Star Formation in NGC 300

Cited by 272 publications

References 30 publications

Properties of M31

Properties of M31

High-resolution, 3D radiative transfer modeling

A dynamical model for the Taffy galaxies UGC 12914/5

Contact Info

Product

Resources

About