On the Use of Trigonometric Parallaxes for the Calibration of Luminosity Systems: Theory

Lutz, T. E.; Kelker, Douglas

doi:10.1086/129506

Cited by 498 publications

(486 citation statements)

References 1 publication

(1 reference statement)

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“…Of the 70 parallax measurements listed in Table 8, about 40 are based on VLBI observations, one (PSR J0633 +1746) based on optical astrometry with the Hubble Space Telescope, and the remainder based on pulse timing analyses. Measured parallaxes of low significance are biased by the "Lutz-Kelker" effect (Lutz & Kelker 1973). This has been considered in the context of pulsar parallax measurements by Verbiest et al (2012) and we have adopted their corrected distance estimates where available.…”

Section: Distances From Annual Parallaxmentioning

confidence: 99%

A New Electron-Density Model for Estimation of Pulsar and FRB Distances

Yao¹,

Manchester²,

Wang³

2017

ApJ

1,021

997

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We present a new model for the distribution of free electrons in the Galaxy, the Magellanic Clouds, and the intergalactic medium (IGM) that can be used to estimate distances to real or simulated pulsars and fast radio bursts (FRBs) based on their dispersion measure (DM). The Galactic model has an extended thick disk representing the so-called warm interstellar medium, a thin disk representing the Galactic molecular ring, spiral arms based on a recent fit to Galactic H II regions, a Galactic Center disk, and seven local features including the Gum Nebula, Galactic Loop I, and the Local Bubble. An offset of the Sun from the Galactic plane and a warp of the outer Galactic disk are included in the model. Parameters of the Galactic model are determined by fitting to 189 pulsars with independently determined distances and DMs. Simple models are used for the Magellanic Clouds and the IGM. Galactic model distances are within the uncertainty range for 86 of the 189 independently determined distances and within 20% of the nearest limit for a further 38 pulsars. We estimate that 95% of predicted Galactic pulsar distances will have a relative error of less than a factor of 0.9. The predictions of YMW16 are compared to those of the TC93 and NE2001 models showing that YMW16 performs significantly better on all measures. Timescales for pulse broadening due to interstellar scattering are estimated for (real or simulated) Galactic and Magellanic Cloud pulsars and FRBs.

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Section: Distances From Annual Parallaxmentioning

confidence: 99%

A New Electron-Density Model for Estimation of Pulsar and FRB Distances

Yao¹,

Manchester²,

Wang³

2017

ApJ

1,021

997

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“…6. Lutz-Kelker corrections (Lutz & Kelker 1973; have not been adopted to refine the Hipparcos parallaxes, as they should not be applied to measurements of individual stars (van Leeuwen 2007, p. 87). Their potential impact is nevertheless rather small for the present sample stars, as visualised in Fig.…”

Section: Stellar Parametersmentioning

confidence: 99%

Present-day cosmic abundances

Nieva

Przybilla²

2012

A&A

432

506

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Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstellar medium (ISM) or H ii regions. Aims. A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Quantitative spectroscopy is used to characterise their atmospheric properties in a self-consistent way. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established. Methods. High-resolution and high-S/N FOCES, FEROS and ELODIE spectra of well-studied sharp-lined early B-type stars are analysed in non-LTE. Line-profile fits based on extensive model grids and an iterative analysis methodology are used to constrain stellar parameters and elemental abundances at high accuracy and precision. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equilibria and the Stark-broadened hydrogen Balmer lines, and they are confirmed by reproduction of the stars' global spectral energy distributions. Results. Effective temperatures are constrained to 1-2% and surface gravities to less than 15% uncertainty, along with accurate rotational, micro-and macroturbulence velocities. Good agreement of the resulting spectroscopic parallaxes with those from the new reduction of the Hipparcos catalogue is obtained. Absolute values for abundances of He, C, N, O, Ne, Mg, Si and Fe are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spectral range. Three sample stars, γ Ori, o Per and θ 1 Ori D, are identified as double-lined, indicating the presence of an early/mid B-type companion. Conclusions. A present-day cosmic abundance standard is established from a sample of 29 early B-type stars, indicating abundance fluctuations of less than 10% around the mean. Our results (i) resolve the long-standing discrepancy between a chemical homogeneous gas-phase ISM and a chemically inhomogeneous young stellar component out to several hundred parsec from the Sun, (ii) facilitate the amount of heavy elements locked up in the interstellar dust to be constrained precisely -the results imply that carbonaceous dust is largely destroyed inside the Orion H ii region, unlike the silicates, and that graphite is only a minority species in interstellar dust -, (iii) show that the mixing of CNO-burning products in the course of massive star evolution follows tightly the predicted nuclear path, (iv) provide reliable present-day reference points for anchoring Galactic chemical evolution models to observation, and (v) imply that the Sun has migrated outwards from the inne...

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“…This traces directly back to a better known example, such as the bias between parallaxes and distances (e.g. Lutz & Kelker 1973;Casagrande et al 2007) Let us consider the case of transforming a magnitude m into a heterochromatic flux F , which (from Eq. 1) involves the following non-linear relation …”

Section: Appendix B: Bias In a Non-linear Transformationmentioning

confidence: 99%

Synthetic stellar photometry – I. General considerations and new transformations for broad-band systems

Casagrande¹,

VandenBerg²

2014

Monthly Notices of the Royal Astronomical Society

257

321

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After a pedagogical introduction to the main concepts of synthetic photometry, colours and bolometric corrections in the Johnson-Cousins, 2MASS, and HST-ACS/WFC3 photometric systems are generated from MARCS synthetic fluxes for various [Fe/H] and [α/Fe] combinations, and virtually any value of E(B − V) 0.7. The successes and failures of model fluxes in reproducing the observed magnitudes are highlighted. Overall, extant synthetic fluxes predict quite realistic broad-band colours and bolometric corrections, especially at optical and longer wavelengths: further improvements of the predictions for the blue and ultraviolet spectral regions await the use of hydrodynamic models where the microturbulent velocity is not treated as a free parameter. We show how the morphology of the colour-magnitude diagram (CMD) changes for different values of [Fe/H] and [α/Fe]; in particular,how suitable colour combinations can easily discriminate between red giant branch and lower main sequence populations with different [α/Fe], due to the concomitant loops and swings in the CMD. We also provide computer programs to produce tables of synthetic bolometric corrections as well as routines to interpolate in them. These colour-T eff -metallicity relations may be used to convert isochrones for different chemical compositions to various bandpasses assuming observed reddening values, thus bypassing the standard assumption of a constant colour excess for stars of different spectral type. We also show how such an assumption can lead to significant systematic errors. The MARCS transformations presented in this study promise to provide important constraints on our understanding of the multiple stellar populations found in globular clusters (e.g., the colours of lower main sequence stars are predicted to depend strongly on [α/Fe]) and of those located towards/in the Galactic bulge.

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On the Use of Trigonometric Parallaxes for the Calibration of Luminosity Systems: Theory

Cited by 498 publications

References 1 publication

A New Electron-Density Model for Estimation of Pulsar and FRB Distances

A New Electron-Density Model for Estimation of Pulsar and FRB Distances

Present-day cosmic abundances

Synthetic stellar photometry – I. General considerations and new transformations for broad-band systems

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