Iron abundances from optical Fe <scp>iii</scp> absorption lines in B-type stellar spectra

Thompson, Henry; Keenan, F. P.; Dufton, P. L.; Trundle, C.; Ryans, R.; Crowther, P. A.

doi:10.1111/j.1365-2966.2007.12597.x

Cited by 9 publications

(4 citation statements)

References 51 publications

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“…We tried but failed to detect absorption lines of doubly ionized ions of Fe-peak elements, which have intermediate second ionization potentials, consulting Kramida et al (2014). Absorption lines of Fe iii are observed in optical range spectra of Btype stars (Thompson et al 2008). This may support the assumption that all of 7 Be and Ca contained in the LVC are in the singly ionized state.…”

Section: Resultssupporting

confidence: 64%

THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

Tajitsu

Sadakane

Naito

et al. 2016

ApJ

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We report spectroscopic observations of the resonance lines of singly ionized 7 Be in the blue-shifted absorption line systems found in the post-outburst spectra of two classical novae -V5668 Sgr (Nova Sagittarii 2015 No. 2) and V2944 Oph (Nova Ophiuchi 2015). The unstable isotope, 7 Be, should has been created during the thermonuclear runaway (TNR) of these novae and decays to form 7 Li within a short period (a half-life of 53.22 days). Confirmations of 7 Be are the second and the third ones following the first case found in V339 Del by Tajitsu et al. (2015). The blue-shifted absorption line systems in both novae are clearly divided into two velocity components, both of which contain 7 Be. This means that the absorbing gases in both velocity components consist of products of TNR. We estimate amounts of 7 Be produced during outbursts of both novae and conclude that significant 7 Li should have been created. These findings strongly suggest that the explosive production of 7 Li via the reaction 3 He(α,γ) 7 Be and subsequent decay to 7 Li occurs frequently among classical novae and contributes to the process of the Galactic Li enrichment.

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Section: Resultssupporting

confidence: 64%

THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

Tajitsu

Sadakane

Naito

et al. 2016

ApJ

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“…The Fe lines were treated in LTE inTrundle et al (2007), though non-LTE effects are thought to be small in the parameter range occupied by the stars in their sample(Thompson et al 2008). …”

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confidence: 99%

Red Supergiants as Cosmic Abundance Probes: The Magellanic Clouds

Davies

Kudritzki

Gazak

et al. 2015

ApJ

104

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Red Supergiants (RSGs) are cool (∼4000 K), highly luminous stars (L 10 5 ∼ L ⊙ ), and are among the brightest near-IR sources in star-forming galaxies. This makes them powerful probes of the properties of their host galaxies, such as kinematics and chemical abundances. We have developed a technique whereby metallicities of RSGs may be extracted from a narrow spectral window around 1 μm from only moderate resolution data. The method is therefore extremely efficient, allowing stars at large distances to be studied, and so has tremendous potential for extragalactic abundance work. Here, we present an abundance study of the Large and Small Magellanic Clouds (LMC and SMC respectively) using samples of 9-10 RSGs in each. We find average abundances for the two galaxies of ). These values are consistent with other studies of young stars in these galaxies, and though our result for the SMC may appear high it is consistent with recent studies of hot stars which find 0.5-0.8 dex below solar. Our best-fit temperatures are on the whole consistent with those from fits to the optical-infrared spectral energy distributions, which is remarkable considering the narrow spectral range being studied. Combined with our recent study of RSGs in the Galactic cluster Per OB1, these results indicate that this technique performs well over a range of metallicities, paving the way for forthcoming studies of more distant galaxies beyond the Local Group.

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“…In the former case, solar values were found (Daflon & Cunha 2004;. For Fe, however, both subsolar ) and solar values have been reported (Thompson et al 2008). The fact that the mean Al, Si and Fe abundances are lower than the accurate meteoritic values supports the idea that the abundances of nearby OB stars are generally underestimated (by up to a factor 2 in the case of Si), perhaps as a result of missing physics or unaccounted systematic errors.…”

Section: -Chemical Composition Of Nearby Ob Stars: Solar?mentioning

confidence: 91%

“…As seen in Fig. 1, most of these ∼150-200 stars are slowly-rotating, early B-type dwarfs/subgiants (data from Cunha & Lambert 1994, Daflon & Cunha 2004and references therein, Gies & Lambert 1992, Gummersbach et al 1998, Kilian 1992, 1994, Lyubimkov et al 2005and Thompson et al 2008. Before comparing the abundances of young OB stars with the solar values, two remarks are necessary.…”

Section: -Chemical Composition Of Nearby Ob Stars: Solar?mentioning

confidence: 99%

Abundances of massive stars: some recent developments

Morel

2008

Preprint

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Thanks to their usefulness in various fields of astrophysics (e.g. mixing processes in stars, chemical evolution of galaxies), the last few years have witnessed a large increase in the amount of abundance data for early-type stars. Two intriguing results emerging since the last reviews on this topic (Herrero 2003;Herrero & Lennon 2004) will be discussed: (a) nearby OB stars exhibit metal abundances generally lower than the solar/meteoritic estimates; (b) evolutionary models of single objects including rotation are largely unsuccessful in explaining the CNO properties of stars in the Galaxy and in the Magellanic clouds.Session: Atmospheres, mass loss and stellar winds -IntroductionThis review about the chemical properties of massive stars will focus on two issues that are relevant in the context of this meeting. First, one may wonder how the chemical abundances of nearby OB stars compare to the solar values. This piece of information is, for instance, needed to properly model B-type pulsators and to draw correct inferences about their internal structure. Second, the abundances of several elements are powerful probes of mixing phenomena and, as such, can be used to improve our theoretical understanding of these processes and ultimately better model the evolution of massive stars across the HR diagram. Fascinating physical phenomena such as mass-transfer processes can affect the abundances of stars in binaries, but we refrain from discussing these systems here (see Langer, these proceedings). -Getting the abundancesA prerequisite to obtain reliable abundances is to adopt accurate atmospheric parameters (a favourable case is offered by detached eclipsing binaries; e.g. Pavlovski & Southworth 2008). The effective temperature can be derived from photometric indices or, preferably, through ionisation balance of some metals (usually Si). The surface gravity is derived by fitting the collisionally-broadened wings of the Balmer lines, while the microturbulent velocity is inferred by requiring the abundances of a given ion to be independent of the line strength. Model atmospheres (either LTE or NLTE) with adequate line-blanketing are required. Departures from LTE are significant in hot stars and a full NLTE treatment for the line formation is also needed. Plane-parallel (e.g. TLUSTY, DETAIL/SURFACE) or so-called unified codes (e.g. CMFGEN, FASTWIND) can be used depending on the strength of the stellar wind. Of course, more sophisticated analysis techniques (NLTE model atmosphere, spherical extension) are much more demanding in terms of computer resources and should be used with discernment. A hybrid approach involving hydrostatic, LTE model atmospheres coupled with an NLTE

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Iron abundances from optical Fe iii absorption lines in B-type stellar spectra

Cited by 9 publications

References 51 publications

THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

Red Supergiants as Cosmic Abundance Probes: The Magellanic Clouds

Abundances of massive stars: some recent developments

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Iron abundances from optical Fe iii absorption lines in B-type stellar spectra

Cited by 9 publications

References 51 publications

THE 7Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

THE 7Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

Red Supergiants as Cosmic Abundance Probes: The Magellanic Clouds

Abundances of massive stars: some recent developments

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THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH

THE ⁷Be ii RESONANCE LINES IN TWO CLASSICAL NOVAE V5668 SGR AND V2944 OPH