Blocking Metal Accretion onto Population III Stars by Stellar Wind

Tanaka, Shuta J.; Chiaki, Gen; Tominaga, Nozomu; Susa, Hajime

doi:10.3847/1538-4357/aa7e2c

Cited by 30 publications

(26 citation statements)

References 145 publications

(175 reference statements)

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“…The line-cooling mechanism and thus the existence of a critical luminosity seems to be observationally supported (Frebel et al, 2007), although the absence of detection of stars below a certain metallicity might be simply a consequence of their rarity and low luminosities, or due to pollution resulting from accretion of interstellar material (Komiya et al, 2015). However, doubts were shed on the latter results by Tanaka et al (2017) and Suzuki (2018). Schneider et al (2012) proposed that the dust produced during the evolution of primordial massive stars and supernova explosions could induce the fragmentation required to form Pop II low-mass stars.…”

Section: The Nature Of Ancient Stars and The History Of Their Modellingmentioning

confidence: 99%

Primordial to extremely metal-poor AGB and Super-AGB stars: White dwarf or supernova progenitors?

Gil‐Pons

Doherty

Gutiérrez

et al. 2018

Publ. Astron. Soc. Aust.

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Getting a better understanding of the evolution and nucleosynthetic yields of the most metal-poor stars (Z 10 −5 ) is critical because they are part of the big picture of the history of the primitive Universe. Yet many of the remaining unknowns of stellar evolution lie in the birth, life, and death of these objects. We review stellar evolution of intermediatemass Z ≤ 10 −5 models existing in the literature, with a particular focus on the problem of their final fates. We emphasize the importance of the mixing episodes between the stellar envelope and the nuclearly processed core, which occur after stars exhaust their central He (second dredge-up and dredge-out episodes). The depth and efficiency of these episodes are critical to determine the mass limits for the formation of electron-capture supernovae (EC-SNe). Our knowledge of these phenomena is not complete because they are strongly affected by the choice of input physics. These uncertainties affect stars in all mass and metallicity ranges. However, difficulties in calibration pose additional challenges in the case of the most metal-poor stars. We also consider the alternative SN I1/2 channel to form supernovae out of the most metal-poor intermediate mass objects. In this case, it is critical to understand the thermally-pulsing AGB evolution until the late stages. Efficient second dredge-up and, later, third dredge-up episodes could be able to pollute stellar envelopes enough for the stars to undergo thermal pulses in a way very similar to that of higher initial Z objects. Inefficient second and/or third dredge-up may leave an almost pristine envelope, unable to sustain strong stellar winds. This may allow the Hexhausted core to grow to the Chandrasekhar mass before the envelope is completely lost, and thus let the star explode as a SN I1/2. After reviewing the information available on these two possible channels for the formation of supernovae, we discuss existing nucleosynthetic yields of stars of metallicity Z ≤ 10 −5 , and present an example of nucleosynthetic calculations for a thermally-pulsing Super-AGB star of Z = 10 −5 . We compare theoretical predictions with observations of the lowest [Fe/H] objects detected. The review closes by discussing current open questions as well as possible fruitful avenues for future research.

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Section: The Nature Of Ancient Stars and The History Of Their Modellingmentioning

confidence: 99%

Primordial to extremely metal-poor AGB and Super-AGB stars: White dwarf or supernova progenitors?

Gil‐Pons

Doherty

Gutiérrez

et al. 2018

Publ. Astron. Soc. Aust.

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“…However, low-mass zero-metal stars have not been discovered yet, in spite of extensive observations of metal-poor stars (Christlieb et al 2004;Aoki et al 2006;Keller et al 2014). Reasons of the non-detection have been discussed from various viewpoints of the surface pollution by heavy elements (Yoshii 1981;Komiya et al 2015;Tanaka et al 2017;Tanikawa et al 2018) Zero-metal stars with the mass M < 0.9M have a convection zone (Richard et al 2002), similarly to the Sun. The surface convective motion in the Sun triggers various magnetic activities, such as (micro-or nano-) flares (e.g.…”

Section: Introductionmentioning

confidence: 99%

Coronae of Zero/Low-metal, Low-mass Stars

Washinoue

Suzuki

2019

ApJ

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Recent theoretical studies suggest the existence of low-mass zero-metal stars in the current universe. In order to study the basic properties of the atmosphere of low-mass first stars, we perform one dimensional magnetohydrodynamical simulations for the heating of coronal loops on low-mass stars with various metallicities. While the simulated loops are heated up to ≥ 10 6 K by the dissipation of Alfvénic waves originating from the convective motion irrespectively of the metallicity, the coronal properties sensitively depend on the metallicity. Lower-metal stars create hotter and denser coronae because the radiative cooling is suppressed. The zero-metal star gives more than 40 times higher coronal density than the solar-metallicity counterpart, and as a result, the UV and X-ray fluxes from the loop are several times higher than those of the solar metallicity star. We also discuss the dependence of the coronal properties on the length of the simulated coronal loops.

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“…III survivors polluted by ISM. However, Johnson (2015) have shown radiation pressure prevents accretion of dust in ISM, and Tanaka et al (2017) have shown stellar wind prevents accretion of gas in ISM. Although stellar wind in their model is Pop.…”

Section: Introductionmentioning

confidence: 99%

“…Eventually, Pop. III survivors have iron abundance [Fe/H] only up to ∼ −14 (Tanaka et al 2017). This metallicity is much smaller than currently discovered very metal deficient stars (e.g.…”

Section: Introductionmentioning

confidence: 99%

Metal pollution of low-mass Population III stars through accretion of interstellar objects like ‘Oumuamua

Tanikawa

Suzuki

Doi

2018

Publications of the Astronomical Society of Japan

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We calculate accretion mass of interstellar objects (ISOs) like 'Oumuamua onto low-mass population III stars (Pop. III survivors), and estimate surface pollution of Pop. III survivors. An ISO number density estimated from the discovery of 'Oumuamua is so high (∼ 0.2 au −3 ) that Pop. III survivors have chances at colliding with ISOs > ∼ 10 5 times per 1 Gyr. 'Oumuamua itself would be sublimated near Pop. III survivors, since it has small size, ∼ 100 m. However, ISOs with size > ∼ 3 km would reach the Pop. III survivor surfaces. Supposing an ISO cumulative number density with size larger than D is n ∝ D −α , Pop. III survivors can accrete ISO mass > ∼ 10 −16 M ⊙ , or ISO iron mass > ∼ 10 −17 M ⊙ , if α < 4. This iron mass is larger than the accretion mass of interstellar medium (ISM) by several orders of magnitude. Taking into account material mixing in a convection zone of Pop. III survivors, we obtain their surface pollution is typically [Fe/H] < ∼ −8 in most cases, however the surface pollution of Pop. III survivors with 0.8M ⊙ can be [Fe/H] > ∼ −6 because of the very shallow convective layer. If we apply to Pop.III survivors located at the Galactocentric distance of 8 kpc, the dependence of the metal pollustion is as follows. If α > 4, Pop. III survivors have no chance at colliding with ISOs with D > ∼ 3 km, and keep metal-free. If 3 < α < 4, Pop. III survivors would be most polluted by ISOs up to [Fe/H] ∼ −7. If α < 3 up to D ∼ 10 km, Pop. III survivors could hide in metal-poor stars so far discovered. Pop. III survivors would be more polluted with decreasing the Galactocentric distance. Although the metal pollution depends on α and the Galactocentric distance, we first show the importance of ISOs for the metal pollution of Pop. III survivors.

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Blocking Metal Accretion onto Population III Stars by Stellar Wind

Cited by 30 publications

References 145 publications

Primordial to extremely metal-poor AGB and Super-AGB stars: White dwarf or supernova progenitors?

Primordial to extremely metal-poor AGB and Super-AGB stars: White dwarf or supernova progenitors?

Coronae of Zero/Low-metal, Low-mass Stars

Metal pollution of low-mass Population III stars through accretion of interstellar objects like ‘Oumuamua

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