<i>Astrophysics of Gaseous Nebulae</i>

Osterbrock, Donald E.; Gull, Theodore R.

doi:10.1063/1.3023426

Cited by 279 publications

(407 citation statements)

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“…The flux in Hα is expected to scale relative to Hβ by a ratio determined by the temperature and electron density of the emitting region. Standard assumptions for these parameters in HII regions (T=10,000 K, low density limit) yields the widely applied expected ratio of 2.87 (see Osterbrock & Ferland 2006). In figure 9, we scale the line fluxes from the GRB host galaxy accordingly, such that, for Case B reionisation, we would expect each line to have the same relative intensity as Hβ.…”

Section: Wht Spectroscopymentioning

confidence: 99%

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

Stanway¹,

Levan²,

Tanvir³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present an analysis of the photometry and spectroscopy of the host galaxy of Swift-detected GRB 080517. From our optical spectroscopy, we identify a redshift of z = 0.089 ± 0.003, based on strong emission lines, making this a rare example of a very local, low luminosity, long gamma ray burst. The galaxy is detected in the radio with a flux density of S 4.5 GHz =0.22±0.04 mJy -one of relatively few known GRB hosts with a securely measured radio flux. Both optical emission lines and a strong detection at 22µm suggest that the host galaxy is forming stars rapidly, with an inferred star formation rate ∼ 16 M ⊙ yr −1 and a high dust obscuration (E(B − V ) > 1, based on sight-lines to the nebular emission regions). The presence of a companion galaxy within a projected distance of 25 kpc, and almost identical in redshift, suggests that star formation may have been triggered by galaxy-galaxy interaction. However, fitting of the remarkably flat spectral energy distribution from the ultraviolet through to the infrared suggests that an older, 500 Myr post-starburst stellar population is present along with the ongoing star formation. We conclude that the host galaxy of GRB 080517 is a valuable addition to the still very small sample of well-studied local gamma-ray burst hosts.

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Section: Wht Spectroscopymentioning

confidence: 99%

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

Stanway¹,

Levan²,

Tanvir³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…Secular Evolution: Bulges form from disc material through redistribution of angular momentum. In this scenario, large amounts of gas are driven into the central region of the galaxy by a stellar bar and trigger intense star formation (e.g., Pfenniger & Norman 1990). If enough mass is accreted, the bar itself will be dissolved and the resulting galaxy will reveal a bigger bulge than before bar formation; galaxies would thus evolve from late to earlier types along the Hubble sequence.…”

Section: Introduction: the Formation Of Bulges Of Spiralsmentioning

confidence: 99%

Untitled

Goudfrooij

Gorgas

Jablonka

1999

Astrophysics and Space Science

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Abstract. We present first results of a comprehensive survey of deep long-slit spectra along the minor axis of bulges of edge-on spiral galaxies. Our results indicate that stellar populations in bulges are fairly old and encompass a range of metallicities. The luminosity-weighted ages of bulges range from those found for cluster ellipticals to slightly "younger" (by up to only a few Gyr, however). Their α/Fe element ratio is typically supersolar, consistent with those found in giant ellipticals. The radial line-strength gradients in bulges correlate with bulge luminosity. Generally, these findings are more compatible with predictions of the "dissipative collapse" model than with those of the "secular evolution" model.

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“…We discretize equations (19) and (20) by integrating these equations from r n to r n+1 . This gives us…”

Section: Methodsmentioning

confidence: 99%