Ultraviolet spectral morphology of the O stars. II - The main sequence

Walborn, N. R.; Panek, R. J.

doi:10.1086/162647

Cited by 43 publications

(26 citation statements)

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“…The age of the star exciting the PDR around the globule may also give a hint of the age of the stellar population, since this star either triggered star formation in the core or began inhibiting it by starting core destruction. If HD 206267 is an O6.5 V star (Walborn & Panek 1984), then its lifetime in the main sequence is ∼6×10 6 yr (e.g. Vanbeveren et al 1998), which roughly agrees with the times given above.…”

Section: The Stellar Populationsupporting

confidence: 85%

The stellar population and complex structure of the bright-rimmed cloud IC 1396N

Beltrán¹,

Massi

López

et al. 2009

A&A

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Context. IC 1396N is a bright-rimmed cloud associated with an intermediate-mass star-forming region, where a number of HerbigHaro objects, H 2 jet-like features, CO molecular outflows, and millimeter compact sources have been observed. Aims. We study the complex structure of the IC 1396N core and the molecular outflows detected in the region in detail and reveal the presence of additional YSOs inside this globule. Methods. We carried out a deep survey of the IC 1396N region in the J, H, K broadband filters and deep high-angular resolution observations in the H 2 narrowband filter with NICS at the TNG telescope. The completeness limits in the 2MASS standard are K s ∼ 17.5, H ∼ 18.5, and J ∼ 19.5. Results. A total of 736 sources have been detected in all three bands within the area where the JHK images overlap. There are 128 sources detected only in HK , 67 detected only in K , and 79 detected only in JH. We found only a few objects exhibiting a near-infrared excess and no clear signs of clustering of sources towards the southern rim. In the case of triggered star formation in the southern rim of the globule, this could be very recent, because it is not shown through Near-Infrared imaging alone. The H 2 emission is complex and knotty and shows a large number of molecular hydrogen features spread over the region, testifying to recent starformation activity throughout the whole globule. This emission is resolved into several chains or groups of knots that sometimes show a jet-like morphology. The shocked cloudlet model scenario previously proposed to explain the V-shaped morphology of the CO molecular outflow powered by the intermediate-mass YSO BIMA 2 seems to be confirmed by the presence of H 2 emission at the position of the deflecting western clump. New possible flows have been discovered in the globule, and some of them could be very long. In particular, the YSO BIMA 3 could be powering an old and poorly collimated outflow.

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Section: The Stellar Populationsupporting

confidence: 85%

The stellar population and complex structure of the bright-rimmed cloud IC 1396N

Beltrán¹,

Massi

López

et al. 2009

A&A

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“…Schaerer & Vacca 1998). At such metallicities, measurements of nebular N v λ1240 and C iv λ1550 are even more challenging, because of the contamination by strong P-Cygni absorption features from O-star winds (Walborn & Panek 1984) coupled with interstellar absorption (see Vidal-García et al, in preparation, for a detailed modelling of these competing effects). Fig.…”

Section: Ultraviolet Emission-line Propertiesmentioning

confidence: 99%

Modelling the nebular emission from primeval to present-day star-forming galaxies

Gutkin

Charlot

Bruzual³

2016

Mon. Not. R. Astron. Soc.

300

523

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We present a new model of the nebular emission from star-forming galaxies in a wide range of chemical compositions, appropriate to interpret observations of galaxies at all cosmic epochs. The model relies on the combination of state-of-the-art stellar population synthesis and photoionization codes to describe the ensemble of H ii regions and the diffuse gas ionized by young stars in a galaxy. A main feature of this model is the self-consistent yet versatile treatment of element abundances and depletion onto dust grains, which allows one to relate the observed nebular emission from a galaxy to both gas-phase and dust-phase metal enrichment. We show that this model can account for the rest-frame ultraviolet and optical emission-line properties of galaxies at different redshifts and find that ultraviolet emission lines are more sensitive than optical ones to parameters such as C/O abundance ratio, hydrogen gas density, dustto-metal mass ratio and upper cutoff of the stellar initial mass function. We also find that, for gas-phase metallicities around solar to slightly sub-solar, widely used formulae to constrain oxygen ionic fractions and the C/O ratio from ultraviolet and optical emission-line luminosities are reasonable faithful. However, the recipes break down at non-solar metallicities, making them inappropriate to study chemically young galaxies. In such cases, a fully self-consistent model of the kind presented in this paper is required to interpret the observed nebular emission.

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“…Walborn (2006) reports that this star shows unexplained spectral peculiarities and/or variations, among them peculiar narrow, variable Si iv emission lines at λ1394 and λ1403 (e.g. Walborn & Panek 1984).…”

Section: Hd 36879mentioning

confidence: 99%

Exploring the origin of magnetic fields in massive stars

Hubrig

Schöller

Ilyin

et al. 2013

A&A

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Context. Theories on the origin of magnetic fields in massive stars remain poorly developed, because the properties of their magnetic field as function of stellar parameters could not yet be investigated. Additional observations are of utmost importance to constrain the conditions that are conducive to magnetic fields and to determine first trends about their occurrence rate and field strength distribution. Aims. To investigate whether magnetic fields in massive stars are ubiquitous or appear only in stars with a specific spectral classification, certain ages, or in a special environment, we acquired 67 new spectropolarimetric observations for 30 massive stars. Among the observed sample, roughly one third of the stars are probable members of clusters at different ages, whereas the remaining stars are field stars not known to belong to any cluster or association. Methods. Spectropolarimetric observations were obtained during four different nights using the low-resolution spectropolarimetric mode of FOcal Reducer low dispersion Spectrograph (FORS 2) mounted on the 8-m Antu telescope of the VLT. Furthermore, we present a number of follow-up observations carried out with the high-resolution spectropolarimeters SOFIN mounted at the Nordic Optical Telescope (NOT) and HARPS mounted at the ESO 3.6 m between 2008 and 2011. To assess the membership in open clusters and associations, we used astrometric catalogues with the highest quality kinematic and photometric data currently available. Results. The presence of a magnetic field is confirmed in nine stars previously observed with FORS

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Ultraviolet spectral morphology of the O stars. II - The main sequence

Cited by 43 publications

References 0 publications

The stellar population and complex structure of the bright-rimmed cloud IC 1396N

The stellar population and complex structure of the bright-rimmed cloud IC 1396N

Modelling the nebular emission from primeval to present-day star-forming galaxies

Exploring the origin of magnetic fields in massive stars

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