Statistical cataloging of archival data for luminosity class IV–V stars

Taylor, Benjamin J.

doi:10.1051/0004-6361:20021674

Cited by 33 publications

(10 citation statements)

References 40 publications

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“…More recent photometric/spectroscopic investigations are: Mishenina et al (2004), T eff = 5590 K; Allende Prieto et al (2004), T eff = 5664 K and Nordström et al (2004), T eff = 5702 K. These consistently low effective temperatures for δ Tri A are then also propagated through reviews or compilations such as Cayrel de Strobel (1996), T eff = 5625 K; Taylor (2003), T eff = 5663 K or Soubiran & Girard (2005), T eff = 5627 K.…”

Section: Visual and Spectroscopic Binaries Or Multiple Systemsmentioning

confidence: 99%

Nearby stars of the Galactic disc and halo – IV

Fuhrmann

2008

Monthly Notices RAS

191

165

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The Milky Way Galaxy has an age of about 13 billion years. Solar‐type stars evolve all the long way to the realm of degenerate objects on essentially this time‐scale. This, as well as the particular advantage that the Sun offers through reliable differential spectroscopic analyses, render these stars the ideal tracers for the fossil record of our parent spiral. Astrophysics is a science that is known to be notoriously plagued by selection effects. The present work – with a major focus in this fourth contribution on model atmosphere analyses of spectroscopic binaries and multiple star systems – aims at a volume‐complete sample of about 300 nearby F‐, G‐, and K‐type stars that particularly avoids any kinematical or chemical pre‐selection from the outset. It thereby provides an unbiased record of the local stellar populations – the ancient thick disc and the much younger thin disc. On this base, the detailed individual scrutiny of the long‐lived stars of both populations unveils the thick disc as a single‐burst component with a local normalization of no less than 20 per cent. This enormous fraction, combined with its much larger scaleheight, implies a mass for the thick disc that is comparable to that of the thin disc. On account of its completely different mass‐to‐light ratio the thick disc thereby becomes the dark side of the Milky Way, an ideal major source for baryonic dark matter. This massive, ancient population consequently challenges any gradual build‐up scenario for our parent spiral. Even more, on the supposition that the Galaxy is not unusual, the thick disc – as it emerges from this unbiased spectroscopic work – particularly challenges the hierarchical cold‐dark‐matter‐dominated formation picture for spiral galaxies in general.

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Section: Visual and Spectroscopic Binaries Or Multiple Systemsmentioning

confidence: 99%

Nearby stars of the Galactic disc and halo – IV

Fuhrmann

2008

Monthly Notices RAS

191

165

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“…The procedure used to derive those values has previously been applied to produce catalogs of averaged values of [Fe/H] for stars on and near the main sequence (see, e.g., Taylor 1994a andTaylor 2005). As part of that procedure, the input metallicities are corrected to a temperature scale based on angular diameters (see, e.g., Taylor 1994a andTaylor 2003).…”

Section: Initial Processing Of Source Datamentioning

confidence: 99%

The Benchmark Cluster Reddening Project. Iv. A Statistical Test for Nonuniform Reddening in the Pleiades

Taylor

2008

The Astronomical Journal

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Using a protocol developed in previous papers in this series, the character of the Pleiades reddening is investigated. The protocol includes (1) analyses that yield results at the few-millimag level of precision and accuracy, (2) derivation of rigorous foundations for reddening values, (3) use of reddening techniques with limited metallicity sensitivity, (4) explicit zero-point control of input data, and (5) use of statistical analysis. It is found that in the eastern part of the Pleiades (as defined in a paper by Breger), E(B − V ) = 34 ± 11 mmag, with the quoted standard error depicting the amount of nonuniform reddening. In the western part of the Pleiades outside the "Southwest Nebula" (where E(B − V ) > 0.2 mag), the mean value of E(B − V ) = 57 ± 5.8 mmag, and the intrinsic rms scatter in E(B − V ) is 32 mmag. These results show that a widely adopted model in which E(B − V ) = 0.04 mag everywhere in the Pleiades outside the Southwest Nebula is not correct for any extended region in the Pleiades. They also show that the photometric properties of brown dwarfs in the western part of the Pleiades are not yet well established. In a collateral analysis, published high-dispersion values of [Fe/H] are used to derive mean metallicities for the Pleiades and Praesepe. The resulting values of [Fe/H] are −0.039 ± 0.014 dex and +0.057 ± 0.022 dex, respectively. When these results are combined with a mean high-dispersion metallicity for the Hyades, it is found that they are strongly inconsistent with a published explanation for the Pleiades distance modulus problem that is based specifically on photometric metallicities.

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“…The continuum normalization was performed using Kurucz synthetic spectra (Kurucz 1993) calculated for an initial guess of the atmospheric parameters and metallicities. When available, temperature and metallicity values were taken from the compilations of Taylor (2003) and Cayrel de Strobel et al (2001), respectively. These preliminary temperature estimates differ by less than 125 K from our final values derived from the excitation equilibrium of the iron lines.…”

Section: Observational Materialsmentioning

confidence: 99%

The photospheric abundances of active binaries

Morel¹,

Micela²,

Favata

et al. 2004

A&A

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Abstract. We report the determination from high-resolution spectra of the atmospheric parameters and abundances of 13 chemical species (among which lithium) in 8 single-lined active binaries. These data are combined with our previous results for 6 other RS CVn systems to examine a possible relationship between the photospheric abundance patterns and the stellar activity level. The stars analyzed are generally found to exhibit peculiar abundance ratios compared to inactive, Galactic disk stars of similar metallicities. We argue that this behaviour is unlikely to be an artefact of errors in the determination of the atmospheric parameters or non-standard mixing processes along the red giant branch, but diagnoses instead the combined action of various physical processes related to activity. The most promising candidates are cool spot groups covering a very substantial fraction of the stellar photosphere or NLTE effects arising from nonthermal excitation. However, we cannot exclude the possibility that more general shortcomings in our understanding of K-type stars (e.g. inadequacies in the atmospheric models) also play a significant role. Lastly, we call attention to the unreliability of the (V − R) and (V − I) colour indices as temperature indicators in chromospherically active stars.

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Statistical cataloging of archival data for luminosity class IV–V stars

Cited by 33 publications

References 40 publications

Nearby stars of the Galactic disc and halo – IV

Nearby stars of the Galactic disc and halo – IV

The Benchmark Cluster Reddening Project. Iv. A Statistical Test for Nonuniform Reddening in the Pleiades

The photospheric abundances of active binaries

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