Wolf-Rayet Stars in the Magellanic Clouds

Smith, Lindsey F.

doi:10.1007/978-94-011-3432-3_64

Cited by 3 publications

(1 citation statement)

References 31 publications

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“…The sterol composition {Table 3) of SG and ASG fractions showed the presence of ~-sitosterol as the predominant sterol and followed a similar pattern of distribution in the component glycolipids of all seed oils. In general, the glycolipid composition of these seeds followed a pattern similar to ricebran (11), soyabean (12), and Briza spicata seeds (13).…”

Section: Resultsmentioning

confidence: 89%

Studies on glycolipids of kenaf, english walnut, myrobalan and manila tamarind seeds of the Vidarbha region (India)

Kulkarni

Khotpal

Bhakara

1991

J Americ Oil Chem Soc

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Studies on the glycolipid compositions of Kenaf, English walnut, Myrobalan and Manila tamarind seeds found in the Vidarbha region of Central India have been carded out by silicic acid column chromatography and thin-layer chromatography (TLC). The total glycolipids have been separated into individual components such as monogala~ tosyldiglycerides 20-28%, digalactosyldiglycerides 40-41%, sterylgalactosides 15-18%, acylated sterylgalactosides 8-15% and unidentified components 0.8-2%. The fatty acid composition of total and component glycolipids as determined by gas-liqnid chromatography (GLC) showed the predominant fatty acids to be palmitic~ stearic and oleic acids. Sugar in the component glycolipids was found to be exclusively galactose.

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Section: Resultsmentioning

confidence: 89%

Studies on glycolipids of kenaf, english walnut, myrobalan and manila tamarind seeds of the Vidarbha region (India)

Kulkarni

Khotpal

Bhakara

1991

J Americ Oil Chem Soc

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A comprehensive study of reported high-metallicity giant H ii regions — II. Ionizing stellar populations

Castellanos

Díaz

Terlevich

2002

Monthly Notices of the Royal Astronomical Society

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The ionizing stellar populations of 11 H II regions in the spiral galaxies: NGC 628, 925, 1232 and 1637, all of them reported to have solar or oversolar abundances according to empirical calibrations, have been analysed using stellar population synthesis models.Four of the observed regions in the sample show features which indicate the presence of a population of Wolf-Rayet (WR) stars with ages between 2.3 and 4.1 Myr. This population is sufficient to explain the emission line spectrum of the low-metallicity region H13 in NGC 628, taking into account the uncertainties involved in both observations and model computations. This is not the case for the rest of the regions for which a second ionizing population is required to simultaneously reproduce both the WR features and the emission line spectrum. Composite populations are also found for half of the regions without WR features, although in this case, the result is based only on the emission line spectrum analysis.For two of the regions showing WR features, no consistent solution is found, as the population containing WR stars produces a spectral energy distribution which is too hard to explain the emission of the gas. Several solutions are proposed to solve this problem.

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Integral field spectroscopy of H ii region complexes: the outer disc of NGC 6946

García-Benito¹,

Díaz²,

Hägele³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Integral field spectroscopy obtained with the Potsdam Multi‐Aperture Spectrophotometer Fiber Package (PPak) and the 3.5‐m telescope at the Calar Alto Observatory has been used to study an outer H ii region complex in the well‐studied galaxy NGC 6946. This technique provides detailed maps of the region in different emission lines, yielding spatially resolved information about the physical properties of the gas. The configuration was chosen to cover the whole spectrum from 3600 up to 10 000 Å, allowing the measurement of the near‐infrared [S iii] lines. We selected four luminous knots to perform a detailed integrated spectroscopic analysis of these structures and of the whole PPak field of view (FOV). For all the knots the electron density has been found to be very similar and below 100 cm−3. The [O iii] electron temperature was measured in knots A, B, C and in the integrated PPak field, and was found to be around 8000 K. The temperatures of [O ii] and [S iii] were estimated in the four cases. The elemental abundances computed from the ‘direct method’ are typical of high‐metallicity disc H ii regions, with a mean value of 12+log(O/H) = 8.65, comparable to what has been found in this galaxy by other authors for regions at similar galactocentric distance. Therefore a remarkable abundance uniformity is found despite the different excitations found throughout the nebula. However, due to the quality of the data, the electron temperatures and metallicities obtained have associated errors comparable to the typical dispersion found in empirical calibrations. Wolf–Rayet (WR) features have been detected in three of the knots, leading to a derived total number of WR stars of 125, 22 and 5 for knots A, C and B, respectively. The ratios of the numbers of WR to O stars are consistent with the prediction of Starburst99 for individual bursts with an age about 4 Myr. Knot D, with no WR features, shows weak Hα emission, low excitation and the lowest Hβ equivalent width, all of which points to a more evolved state. The integrated spectrum of the whole PPak FOV shows high excitation and a relatively evolved age that does not correspond to the individual knot evolutionary stages. Some effects associated with the loss of spatial resolution are also evidenced by the higher ionizing temperature that is deduced from the η′ parameter measured in the integrated PPak spectrum with respect to that of the individual knots.

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Wolf-Rayet Stars in the Magellanic Clouds

Cited by 3 publications

References 31 publications

Studies on glycolipids of kenaf, english walnut, myrobalan and manila tamarind seeds of the Vidarbha region (India)

Studies on glycolipids of kenaf, english walnut, myrobalan and manila tamarind seeds of the Vidarbha region (India)

A comprehensive study of reported high-metallicity giant H ii regions — II. Ionizing stellar populations

Integral field spectroscopy of H ii region complexes: the outer disc of NGC 6946

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