Multiwavelength Study of the Starburst Galaxy NGC 7714. I. Ultraviolet‐Optical Spectroscopy

Delgado, R. M. González; García-Vargas, María Luisa; Goldader, J. D.; Leitherer, Claus; Pasquali, A.

doi:10.1086/306893

Cited by 34 publications

(30 citation statements)

References 73 publications

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“…In the optical spectrum of their region A (our region 4) 5 SE of the nucleus, they detect Ca II triplet absorption 8600Å features, compatible with two populations, the ionizing population with age ∼5 Myr, and a relatively young RSG-rich population of ∼10 Myr, responsible for the Ca triplet and the Balmer absorption. Further modeling of the UV -NIR spectrum of the nucleus of NGC 7714 (Gonzalez-Delgado et al 1999) found a best fit for a ∼4.5 Myr burst, with upper mass cutoff > 40 M . Gonzalez-Delgado et al (1999) derive a SN rate = 0.007 yr −1 both from the spectral modelling and from radio emission, consistent with the nondetection of SNe in NGC 7714 in the monitoring by Richmond, Filippenko & Galisky (1998).…”

Section: In Amentioning

confidence: 99%

“…Further modeling of the UV -NIR spectrum of the nucleus of NGC 7714 (Gonzalez-Delgado et al 1999) found a best fit for a ∼4.5 Myr burst, with upper mass cutoff > 40 M . Gonzalez-Delgado et al (1999) derive a SN rate = 0.007 yr −1 both from the spectral modelling and from radio emission, consistent with the nondetection of SNe in NGC 7714 in the monitoring by Richmond, Filippenko & Galisky (1998).…”

Section: In Amentioning

confidence: 99%

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Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714

Kotilainen

Reunanen

Laine

et al. 2001

A&A

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Abstract. We present high spatial resolution (∼0. 6) near-infrared broad-band JHK images and Brγ 2.1661 µm and H 2 1-0 S(1) 2.122 µm emission line images of the nuclear regions in the interacting starburst galaxies NGC 520, NGC 1614 and NGC 7714. The near-infrared emission line and radio morphologies are in general agreement, although there are differences in details. In NGC 1614, we detect a nuclear double structure in Brγ, in agreement with the radio double structure. We derive average extinctions of A K = 0.41 and A K = 0.18 toward the nuclear regions of NGC 1614 and NGC 7714, respectively. For NGC 520, the extinction is much higher, A K = 1.2 -1.6. The observed H 2 /Brγ ratios indicate that the main excitation mechanism of the molecular gas is fluorescence by intense UV radiation from clusters of hot young stars, while shock excitation can be ruled out.The starburst regions in all galaxies exhibit small Brγ equivalent widths. Assuming a constant star formation model, even with a lowered upper mass cutoff of M u = 30 M , results in rather old ages (10 -40 Myr), in disagreement with the clumpy near-infrared morphologies. We prefer a model of an instantaneous burst of star formation with M u = 100 M , occurring ∼6-7 Myr ago, in agreement with previous determinations and with the detection of W-R features in NGC 1614 and NGC 7714. Finally, we note a possible systematic difference in the amount of hot molecular gas between starburst and Seyfert galaxies.

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Section: In Amentioning

confidence: 99%

Section: In Amentioning

confidence: 99%

Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714

Kotilainen

Reunanen

Laine

et al. 2001

A&A

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“…Strong Hα emission indicates a large nuclear H ii region and ongoing star formation (González Delgado et al 1995; Smith, Struck & Pogge 1997). O and B stars are required to fit the UV spectrum, with a best‐fitting age ∼5 Myr and a burst of star formation favoured over continuous star formation (González Delgado et al 1999).…”

Section: Tidal Star‐forming Environments Of Arp 284mentioning

confidence: 99%

“… c Ages determined by photoionization modelling for A, B, C (García‐Vargas et al 1997). Ages for F determined by spectral line synthesis (Gonzáles Delgado et al 1999) and SN rate (Lançon et al 2001). …”

Section: Hst Data Analysismentioning

confidence: 99%

Star clusters in the interacting galaxy system Arp 284

Peterson

Struck

Smith

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We present results from a study of protoglobular cluster candidates in the interacting galaxy system Arp 284 (NGC 7714/5) using data from the Hubble Space Telescope (HST). Previous studies of the Antennae and M51 have suggested that the majority of young massive star clusters dissolve within 20 Myr due to mass loss. We use the evolutionary synthesis code STARBURST99 to estimate ages and extinctions for approximately 175 clusters visible with HST. We also use lower resolution Galaxy Evolution Explorer and ground-based Hα data to estimate the ages of the giant H II regions in which these clusters are found, and compare the Spitzer colours of these H II regions to those of star-forming regions in other interacting systems. The ages are also used to aid in the interpretation of Chandra X-ray data.Clusters in the tidal tails of NGC 7714 are generally found to have ages less than 20 Myr, though observational limits make the significance of this result uncertain. Older clusters, though not numerous, have nearly the same spatial distribution within the imaged portion of NGC 7714 as young clusters. The cluster population in the bridge connecting the two galaxies appears to be older, but the data in this part of the system are too limited to draw firm conclusions. The ages of the giant H II regions in NGC 7714 are generally older than those of their constituent clusters, possibly indicating that the young clusters we detect are surrounded by their dispersed predecessors.Key words: galaxies: individual: NGC 7714, NGC 7715 -galaxies: interactions -galaxies: star clusters. I N T RO D U C T I O NThe study of star formation in interacting galaxies has been revolutionized by the Hubble Space Telescope (HST). One of the early results to emerge from HST was the discovery of a class of bright, blue clusters 300 Myr old in the peculiar elliptical galaxy NGC 1275 (Holtzman et al. 1992). These young massive clusters (YMCs) were also found in the prototypical merger remnant NGC 7252, with ages ranging from 34 to 500 Myr, consistent with the age of the merger (Whitmore et al. 1993). Many more examples soon followed, in which it was found that the properties of these YMCs implied that they might be young globular clusters, though with higher abundances (Conti & Vacca 1994;Hunter, O'Connell & Gallagher 1994).In interacting galaxy systems, in which star-forming regions are abundant, the high resolution of HST has allowed the study of star cluster demographics. Among the results to emerge from such studies is the apparent dissolution of young star clusters, also known as infant mortality. Fall, Chandar & Whitmore (2005) used evolution-E-mail: bwp@iastate.edu (BWP); curt@iastate.edu (CS) ary synthesis models to estimate the ages of clusters in the Antennae and found that 90 per cent of clusters vanish over each age dex from 10 6 up to 10 9 yr, suggesting that cluster dissolution continues over very long time-scales. In contrast, Bastian et al. (2005a) found in M51 that 70 per cent of clusters dissolve in the first 20 Myr, indicat...

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“…The effective Strömgren radius is obtained only at the end of a CLOUDY calculation. The spherical geometry (Stasińska & Leitherer 1996;González-Delgado et al 1999) and plane-parallel geometry (García-Vargas & Díaz 1994;García-Vargas et al 1997) are extreme situations for which the right-hand side of eq. (3) is respectively dominated by the first and the second term.…”

Section: Physical Properties Of the Gasmentioning

confidence: 99%

Evolution of photoionization and star formation in starbursts and H1214 II galaxies

Moy

Rocca‐Volmerange

Fioc

2001

A&A

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Abstract. We analyze coherently the stellar and nebular energy distributions of starbursts and H ii galaxies, using our evolutionary synthesis model, PÉGASE (Fioc & Rocca-Volmerange 1997, 2000, coupled to the photoionization code CLOUDY (Ferland 1996). The originality of this study is to relate the evolution and the metallicity of the starburst to the past star formation history of the host galaxy. Extinction and geometrical effects on emission lines and continua are computed in coherency with metallicity. We compare our model predictions to an observed sample of ≈ 750 H ii regions and starbursts.When/Hβ, the most striking feature is the decreasing spread in U with increasing metallicity Z. High-U objects systematically have a low metallicity while low levels of excitation happen at any Z. The best fits of emission line ratios are obtained with a combination of a high-and a low-ionization components. No additional source of ionizing photons -shocks or hidden AGN -is needed. The high level of excitation observed in metal-poor H ii galaxies requires a very young population (≤ 3 Myr), while starburst nuclear galaxies (SBNGs) are consistent with a wider range of age (≤ 5 Myr).Colors (B − V , V − R) and equivalent widths are fitted in coherency with emission line ratios. An underlying population is needed, even for small-aperture observations. This evolved population not only reddens the continuum and dilutes the equivalent width of the emission lines, but also participates in the ionization process. Its main effect on line ratios is to maintain a high level of excitation when the burst stops. Models combining underlying populations typical of Hubble sequence galaxies and instantaneous starbursts with ages between 0 and 8 Myr agree satisfactorily with all the data.

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Multiwavelength Study of the Starburst Galaxy NGC 7714. I. Ultraviolet‐Optical Spectroscopy

Cited by 34 publications

References 73 publications

Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714

Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714

Star clusters in the interacting galaxy system Arp 284

Evolution of photoionization and star formation in starbursts and H1214 II galaxies

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