Transition of the initial mass function in the galaxy based on binary population synthesis

Suda, Takuma; Komiya, Yutaka; Yamada, Shimako; Katsuta, Yutaka; Aoki, Wako; Gil‐Pons, Pilar; Doherty, Carolyn; Campbell, Simon; Wood, P. R.; Fujimoto, Masayuki Y.

doi:10.1063/1.4754407

Cited by 52 publications

(75 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The positive correlation between carbon and barium abundances observed in EMP stars indicates that carbon and s-process elements might have a common production site (Aoki et al 2002;Suda et al 2004Suda et al , 2011. Stars with a metallicity of [Fe/H] ≤ −2.5 in the mass range of 1.2 M < M ≤ 3.0 M also experience a PIE during the first one or two thermal pulses in the beginning of the thermally pulsating asymptotic giant branch (TP-AGB) phase.…”

Section: Introductionmentioning

confidence: 99%

“…The abundance patterns of EMP stars observed with high resolution spectroscopy are peculiar. A most conspicuous finding is that the fraction of EMP stars that are carbon enhanced ([C/Fe] > 0.9; Masseron et al 2010) is ∼20% (Rossi et al 1999;Suda et al 2011), which is much larger than the ∼1% found in more metal-rich stars (Tomkin et al 1989;Luck & Bond 1991). In terms of neutron capture elements, EMP stars also have a wide variety of patterns with stars showing no signatures of these elements to others having large enhancements in either s-process, r-process elements, or both (Beers & Christlieb 2005).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

S-process in extremely metal-poor, low-mass stars

Cruz¹,

Serenelli²,

Weiß³

2013

A&A

View full text Add to dashboard Cite

Context. Extremely metal-poor (EMP), low-mass stars experience an ingestion of protons into the helium-rich layer during the core He-flash, resulting in the production of neutrons through the reactions 12 C(p, γ) 13 N(β) 13 C(α, n) 16 O. This is a potential site for the production of s-process elements in EMP stars, which does not occur in more metal-rich counterparts. The signatures of s-process elements in the two most iron deficient stars observed to date, HE1327-2326 & HE0107-5240, still await for an explanation. Aims. We investigate the possibility that low-mass EMP stars could be the source of s-process elements observed in extremely iron deficient stars, either as a result of self-enrichment or in a binary scenario as the consequence of a mass transfer episode. Methods. We present evolutionary and post-processing s-process calculations of a 1 M stellar model with metallicities of Z = 0, 10 −8 , and 10 −7 . We assess the sensitivity of nucleosynthesis results to uncertainties in the input physics of the stellar models with particular regard to the details of convective mixing during the core He-flash. Results. Our models provide the possibility of explaining the C, O, Sr, and Ba abundance for the star HE0107-5240 as the result of mass-transfer from a low-mass EMP star. The drawback of our model is that nitrogen would be overproduced and the 12 C/ 13 C abundance ratio would be underproduced in comparison to the observed values if mass would be transferred before the primary star enters the asymptotic giant branch phase. Conclusions. Our results show that low-mass EMP stars cannot be ruled out as companion stars that might have polluted HE1327-2326 and HE0107-5240 and produced the observed s-process pattern. However, more detailed studies of the core He-flash and the proton ingestion episode are needed to determine the robustness of our predictions.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

S-process in extremely metal-poor, low-mass stars

Cruz¹,

Serenelli²,

Weiß³

2013

A&A

View full text Add to dashboard Cite

show abstract

“…Prochaska & Wolfe 2002) and also in metal-poor stars of our Galactic Halo, which must have preserved the abundance pattern of the young Milky Way (e.g. Nissen et al 2004;Suda et al 2011;Rafelski et al 2012). In the case of absorption line systems, the conclusion is less straight-forward, because the lack of iron in the gas can also be attributed to dust-depletion.…”

Section: Abundances From Ion Ratiosmentioning

confidence: 99%

VLT/UVES observations of peculiarαabundances in a sub-DLA atz≈ 1.8 towards the quasar B1101−26

Fox¹,

Richter²,

Fechner³

2014

A&A

View full text Add to dashboard Cite

We present a detailed analysis of chemical abundances in a sub-damped Lyman α absorber at z = 1.839 towards the quasar B1101−26, based on a very-high-resolution (R ∼ 75 000) and high-signal-to-noise (S /N > 100) spectrum observed with the UV Visual Echelle spectrograph (UVES) installed on the ESO Very Large Telescope (VLT). The absorption line profiles are resolved into a maximum of eleven velocity components spanning a rest-frame velocity range of ≈200 km s −1 . Detected ions include C , We calculate detailed photoionisation models for two subcomponents with Cloudy, and can rule out that ionisation effects alone are responsible for the high S/O ratio. We instead speculate that the high S/O ratio is caused by the combination of several effects, such as specific ionisation conditions in multi-phase gas, unusual relative abundances of heavy elements, and/or dust depletion in a local gas environment that is not well mixed and/or that might be related to star-formation activity in the host galaxy. We discuss the implications of our findings for the interpretation of α-element abundances in metal absorbers at high redshift.

show abstract

“…To compare our models with observations we use a database of VMP stars based on the SAGA observational database compiled by Suda et al (2008Suda et al ( , 2011, combined with data of metal-poor stars from Frebel et al (2006) and from Lucatello et al (2006). We select stars corresponding to our VMP criteria: (i) the iron abundance is in the range [Fe/H] = −2.3 ± 0.5 dex and (ii) the star is a giant or a sub-giant, with log 10 (g/cm s −2 ) ≤ 4.0 (in the database of Frebel et al 2006, stars are catalogued as giants or sub-giants according to their B − V colour).…”

Section: Distributions Of Carbon and Nitrogenmentioning

confidence: 99%

Wind Roche-lobe overflow: Application to carbon-enhanced metal-poor stars

Abate

Pols

Izzard³

et al. 2013

A&A

168

251

View full text Add to dashboard Cite

Carbon-enhanced metal-poor (CEMP) stars are observed as a substantial fraction of the very metal-poor stars in the Galactic halo. Most CEMP stars are also enriched in s-process elements, and these are often found in binary systems. This suggests that the carbon enrichment is due to mass transfer in the past from an asymptotic giant branch (AGB) star on to a low-mass companion. Models of binary population synthesis are not able to reproduce the observed fraction of CEMP stars without invoking non-standard nucleosynthesis or a substantial change in the initial mass function. This is interpreted as evidence of missing physical ingredients in the models. Recent hydrodynamical simulations show that efficient wind mass transfer is possible in the case of the slow and dense winds typical of AGB stars through a mechanism called wind Roche-lobe overflow (WRLOF), which lies in between the canonical Bondi-Hoyle-Lyttleton (BHL) accretion and Roche-lobe overflow. WRLOF has an effect on the accretion efficiency of mass transfer and on the angular momentum lost by the binary system. The aim of this work is to understand the overall effect of WRLOF on the population of CEMP stars. To simulate populations of low-metallicity binaries we combined a synthetic nucleosynthesis model with a binary population synthesis code. In this code we implemented the WRLOF mechanism. We used the results of hydrodynamical simulations to model the effect of WRLOF on the accretion efficiency, and we took the effect on the angular momentum loss into account by assuming a simple prescription. The combination of these two effects widens the range of systems that become CEMP stars towards longer initial orbital periods and lower mass secondary stars. As a consequence the number of CEMP stars predicted by our model increases by a factor 1.2−1.8 compared to earlier results that consider the BHL prescription. Moreover, higher enrichments of carbon are produced, and the final orbital period distribution is shifted towards shorter periods.

show abstract

Transition of the initial mass function in the galaxy based on binary population synthesis

Cited by 52 publications

References 0 publications

S-process in extremely metal-poor, low-mass stars

S-process in extremely metal-poor, low-mass stars

VLT/UVES observations of peculiarαabundances in a sub-DLA atz≈ 1.8 towards the quasar B1101−26

Wind Roche-lobe overflow: Application to carbon-enhanced metal-poor stars

Contact Info

Product

Resources

About