A Very Large Telescope imaging and spectroscopic survey of the Wolf-Rayet population in NGC 7793★

Bibby, Joanne; Crowther, P. A.

doi:10.1111/j.1365-2966.2010.16659.x

Cited by 23 publications

(40 citation statements)

References 81 publications

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“…This follows the recent line of discussion in observational studies of WR populations (e.g. Crowther 2007; B08a; López-Sánchez & Esteban 2010;Bibby & Crowther 2010Kehrig et al 2013).…”

Section: Wr Ratios and Predictions From Stellar Population Modelssupporting

confidence: 80%

“…Previous searches for WR regions across individual galaxies outside the Local Group have been performed, for example in NGC 300 (Schild et al 2003), M83 (Hadfield et al 2005), NGC 1313 (Hadfield & Crowther 2007), NGC 7793 (Bibby & Crowther 2010), NGC 5068 (Bibby & Crowther 2012), and M101 (Shara et al 2013). Currently, a systematic search for the spatially resolved WR populations in a sample of nearby galaxies can be performed with the aid of IFS.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

Miralles-Caballero¹,

Díaz²,

López-Sánchez³

et al. 2016

A&A

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The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task owing to the difficulty in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This procedure has been applied to a sample of nearby galaxies spanning a wide range of physical, morphological, and environmental properties. This technique allowed us to build the first catalogue of regions rich in WR stars with spatially resolved information, and enabled us to study the properties of these complexes in a two-dimensional (2D) context. The detection technique is based on the identification of the blue WR bump (around He ii λ4686 Å, mainly associated with nitrogen-rich WR stars; WN) and the red WR bump (around C iv λ5808 Å, mainly associated with carbon-rich WR stars; WC) using a pixel-by-pixel analysis that maximizes the number of independent regions within a given galaxy. We identified 44 WR-rich regions with blue bumps distributed in 25 out of a total of 558 galaxies. The red WR bump was identified only in 5 of those regions. Most of the WR regions are located within one effective radius from the galaxy centre, and around one-third are located within ∼1 kpc or less from the centre. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, such as potential candidates to the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as binary star channel (which could extend the WR phase up to 10 Myr), fast rotation, or other physical processes that cause the loss of observed Lyman continuum photons, very likely affect the derived WR properties, and hence should be considered when modelling the evolution of massive stars.

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“…This follows the recent line of discussion in observational studies of WR populations (e.g. Crowther 2007; B08a; López-Sánchez & Esteban 2010;Bibby & Crowther 2010Kehrig et al 2013).…”

Section: Wr Ratios and Predictions From Stellar Population Modelssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

Miralles-Caballero¹,

Díaz²,

López-Sánchez³

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…As a comparison, and to show the improvement of our data set over the existing literature, we have considered the line fluxes of H II regions in NGC 7793 from Bibby & Crowther (2010) and Webster & Smith (1983; as corrected by Moustakas et al 2010) whose oxygen abundances we recalculate following the N2 method (Marino et al 2013) and found a gradient slope ∼−0.270 dex R . 25 1 -The gradient described by our own abundances has considerably less scatter (the O3S2N2 calibration gives a linear correlation R xy ∼ −0.8) than that from the existing literature data (R xy = −0.6).…”

Section: Radial Oxygen Gradients and Characteristic Abundancesmentioning

confidence: 99%

Gas-Phase Oxygen Abundances and Radial Metallicity Gradients in the Two Nearby Spiral Galaxies NGC 7793 and NGC 4945

Stanghellini

Magrini

Casasola

2015

ApJ

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Gas-phase abundances in H II regions of two spiral galaxies, NGC 7793 and NGC 4945, have been studied to determine their radial metallicity gradients. We used the strong-line method to derive oxygen abundances from spectra acquired with GMOS-S, the multi-object spectrograph on the 8 m Gemini South telescope. We found that NGC 7793 has a well-defined gas-phase radial oxygen gradient of −0.321 ± 0.112 dex R 25) in the galactocentric range 0.17 < R G /R 25 < 0.82, not dissimilar from gradients calculated with direct abundance methods in galaxies of similar mass and morphology. We also determined a shallow radial oxygen gradient in NGC 4945, −0.253 ± 0.149 dex R 25 1 -(or −0.019 ± 0.011 dex kpc −1 ) for 0.04 < R G / R 25 < 0.51, where the larger relative uncertainty derives mostly from the larger inclination of this galaxy. NGC 7793 and NGC 4945 have been selected for this study because they are similar, in mass and morphology, to M33 and the Milky Way, respectively. Since at zeroth order we expect the radial metallicity gradients to depend on mass and galaxy type, we compared our galaxies in the framework of radial metallicity models best suited for M33 and the Galaxy. We found a good agreement between M33 and NGC 7793, pointing toward similar evolution for the two galaxies. We notice instead differences between NGC 4945 and the radial metallicity gradient model that best fits the Milky Way. We found that these differences are likely related to the presence of an active galactic nucleus combined with a bar in the central regions of NGC 4945, and to its interacting environment.

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“…The two new galaxies have somewhat intermediate properties between these two. As discussed by Bibby & Crowther (2010, 2012, they both demonstrate important metallicity gradients encompassing both solar and LMC values. Another important difference is that these galaxies are more nearby.…”

Section: Comparison With Locations Of Wr Starsmentioning

confidence: 92%

The locations of SNe Ib/c and their comparison to those of WR stars and GRBs

Leloudas

2011

Proc. IAU

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Abstract.The locations of long GRBs and stripped supernovae are compared to those of their favored progenitors, WR stars, and their sub-classes. Compared to Leloudas et al. (2010), we have doubled the number of galaxies with suitable WR data. In the combined sample, WC stars are found, on average, in brighter locations than WN stars. The WN distribution is fully consistent with the one of SNe Ib, while it is inconsistent with those of SNe II, Ic and GRBs. The WC distribution is both consistent with SNe Ib and Ic. It is inconsistent with SNe II, and marginally consistent with GRBs. Furthermore, we present a spectroscopic study of the locations of SNe Ib/c. The average metallicity in the environments of SNe Ic is found to be a little higher than for SNe Ib, but the difference is small and not significant within our sample. Under the assumption that the SN regions were formed in an instantaneous burst of star formation, we find that a fraction of them appear older than what is allowed in order to host SNe Ib/c from single massive stars. Within this framework, these SNe must come from lower mass binaries.

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A Very Large Telescope imaging and spectroscopic survey of the Wolf-Rayet population in NGC 7793★

Cited by 23 publications

References 81 publications

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

Gas-Phase Oxygen Abundances and Radial Metallicity Gradients in the Two Nearby Spiral Galaxies NGC 7793 and NGC 4945

The locations of SNe Ib/c and their comparison to those of WR stars and GRBs

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