Simulating multiple stars in preparation for Gaia

Arenou, Frédéric; Docobo, J. A.; Tamazian, V. S.; Balega, Y. Y.

doi:10.1063/1.3597593

Cited by 41 publications

(52 citation statements)

References 36 publications

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“…For physical binaries, some tests were developed to estimate the change in their photometric indexes and in turn the error introduced when ignoring binarity. Their binarity ratio is debated, but according to Arenou (2010) 1) it can reach up to 80% for the more massive stars; and 2) the mass ratio between the stars has a probability peak around M 2 /M 1 = 0.6, with about 10% of cases with a mass ratio higher than M 2 /M 1 = 0.8.…”

Section: Appendix B: Binarity Effectmentioning

confidence: 99%

Stellar physical parameters from Strömgren photometry

Monguió¹,

Figueras²,

Grosbøl³

2014

A&A

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Aims. The aim is to derive accurate stellar distances and extinctions for young stars of our survey in the Galactic anticenter direction using the Strömgren photometric system. This will allow a detailed mapping of the stellar density and absorption toward the Perseus arm. Methods. We developed a new method for deriving physical parameters from Strömgren photometry and also implemented and tested it. This is a model-based method that uses the most recent available stellar atmospheric models and evolutionary tracks to interpolate in a 3D grid of the unreddened indexes [m 1 ], [c 1 ] and Hβ. Distances derived from both this method and the classical pre-Hipparcos calibrations were tested against Hipparcos parallaxes and found to be accurate. Results. Systematic trends in stellar photometric distances derived from empirical calibrations were detected and quantified. Furthermore, a shift in the atmospheric grids in the range T eff = [7000, 9000] K was detected and a correction is proposed. The two methods were used to compute distances and reddening for ∼12 000 OBA-type stars in our Strömgren anticenter survey. Data from the IPHAS and 2MASS catalogs were used to complement the detection of emission line stars and to break the degeneracy between early and late photometric regions. We note that photometric distances can differ by more than 20%, those derived from the empirical calibrations being smaller than those derived with the new method, which agree better with the Hipparcos data.

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Section: Appendix B: Binarity Effectmentioning

confidence: 99%

Stellar physical parameters from Strömgren photometry

Monguió¹,

Figueras²,

Grosbøl³

2014

A&A

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“…Binaries are implemented by following the scheme proposed by Arenou (2011), which is applied in the Gaia simulator (Robin et al 2012a). The thorough explanation of the algorithm and the observational data, which were used to set the empirical relations adopted in this scheme, can be found in those articles.…”

Section: Binaritymentioning

confidence: 99%

The Besançon Galaxy model renewed

Czekaj

Robin

Figueras

et al. 2014

A&A

130

219

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Context. The understanding of Galaxy evolution can be facilitated by the use of population synthesis models, which allows us to test hypotheses on the star formation history, star evolution, and chemical and dynamical evolution of the Galaxy. Aims. The new version of the Besançon Galaxy model (BGM) aims to provide a more flexible and powerful tool to investigate the initial mass function (IMF) and star formation rate (SFR) of the Galactic disc. Methods. We present a new strategy for the generation of thin disc stars, which assumes the IMF, SFR and evolutionary tracks as free parameters. We have updated most of the ingredients for the star count production and, for the first time, binary stars are generated in a consistent way. The local dynamical self-consistency is maintained in this new scheme. We then compare simulations from the new model with Tycho-2 data and the local luminosity function, as a first test to verify and constrain the new ingredients. The effects of changing thirteen different ingredients of the model are systematically studied. Results. For the first time, a full sky comparison is performed between BGM and data. This strategy allows us to constrain the IMF slope at high masses, which is found to be close to 3.0 and excludes a shallower slope such as Salpeter's one. The SFR is found decreasing whatever IMF is assumed. The model is compatible with a local dark matter density of 0.011 M pc −3 implying that there is no compelling evidence for the significant amount of dark matter in the disc. While the model is fitted to Tycho-2 data, which is a magnitude limited sample with V < 11, we check that it is still consistent with fainter stars. Conclusions. The new model constitutes a new basis for further comparisons with large scale surveys and is being prepared to become a powerful tool for the analysis of the Gaia mission data.

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“…This version of BGM does not take binary and multiple stars into account, but a new revision by Czekaj et al (2014) builds in binary populations as well, following the formalism of Arenou (2011). For the purpose of this simulation only single stars are generated, so for remote populations the luminosity functions represent more systems than single stars.…”

Section: The New Besançon Modelmentioning

confidence: 99%

Stellar statistics along the ecliptic and the impact on the K2 mission concept

Prša

Robin

Barclay

2014

International Journal of Astrobiology

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K2 is the mission concept for a repurposed Kepler mission that uses two reaction wheels to maintain the satellite attitude and provide ∼85 days of coverage for ten 105-deg 2 fields along the ecliptic in the first 2.5 years of operation. We examine stellar populations based on the improved Besançon model of the Galaxy, comment on the general properties for the entire ecliptic plane, and provide stellar occurrence rates in the first 6 tentative K2 campaigns grouped by spectral type and luminosity class. For each campaign we distinguish between main sequence stars and giants and provide their density profile as a function of galactic latitude. We introduce the crowding metric that serves for optimized target selection across the campaigns. For all main sequence stars we compute the expected planetary occurrence rates for three planet sizes: 2-4 R ⊕ , 4-8 R ⊕ , and 8-32 R ⊕ with orbital periods up to 50 days. In conjunction with Gaia and the upcoming TESS and Plato missions, K2 will become a gold mine for stellar and planetary astrophysics.

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Simulating multiple stars in preparation for Gaia

Cited by 41 publications

References 36 publications

Stellar physical parameters from Strömgren photometry

Stellar physical parameters from Strömgren photometry

The Besançon Galaxy model renewed

Stellar statistics along the ecliptic and the impact on the K2 mission concept

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